Ketosis and appetite-mediating nutrients and hormones after weight loss

Is severe carbohydrate restriction necessary for appetite suppression? The ASKED randomized controlled trial

OBJECTIVE

This trial aimed to compare three low-energy diets (LEDs) with different amounts of carbohydrates (CHO) on ketosis and changes in hunger feelings in adults with obesity.

METHODS

A total of 101 adults (51 female) with obesity (BMI, mean [SEM], 34.7 [0.4] kg/m2) were randomized to follow three isocaloric LEDs (1000 kcal/day) for 8 weeks, containing either low, medium, or high CHO (70, 100, and 130 g/day, respectively), and 4 weeks of refeeding and weight stabilization. Body weight (BW) and composition, hunger and other appetite ratings, concentrations of β-hydroxybutyrate (βHB), and appetite-related hormones were measured at baseline and at the end of weeks 8 and 12.

RESULTS

At week 8, weight loss and βHB concentrations were significantly different among groups: Low CHO group versus Medium CHO group (BW: 2.32 [0.95] kg, 95% CI: 0.44 to 4.21, p = 0.016; βHB: -0.40 [0.09] mM, 95% CI: -0.67 to -0.09, p < 0.001); Low CHO group versus High CHO group (BW: 2.29 [0.96] kg, 95% CI: 0.39 to 4.19, p = 0.016; βHB: -0.644 [0.10] mM, 95% CI: -0.84 to -0.44, p < 0.001); and Medium CHO group versus High CHO group (BW: -0.03 [0.94] kg, 95% CI: -1.89 to 1.84, p = 0.977; βHB: -0.15 [0.08] mM, 95% CI: -0.30 to 0.002, p = 0.054). No significant differences in hunger were found among groups: Low CHO group versus Medium CHO group (-10.87 [5.92] mm, 95% CI: -0.82 to 22.57, p = 0.068); Low CHO group versus Medium CHO group (7.74 [7.36] mm, 95% CI: -6.77 to 22.26, p = 0.294); and Medium CHO group versus High CHO group (-3.13 [7.48] mm, 95% CI: -17.89 to 11.63, p = 0.676).

CONCLUSIONS

Although the findings of this trial are not definitive, changes in hunger ratings with weight loss did not differ among groups. Additional studies with CHO intake of up to 130 g in 1000-kcal/day LEDs are warranted to replicate these findings.

Exploring Experiences of People With Knee Osteoarthritis Who Received a Physiotherapist-Delivered Dietary Weight Loss and Exercise Intervention: A Mixed Methods Study

OBJECTIVE

Explore the experiences of people with knee osteoarthritis (OA) who received a very low energy diet (VLED) and exercise program from a physiotherapist.

METHODS

Mixed methods study involving questionnaires (n = 42) and semistructured interviews (n = 22) with randomized control trial participants with knee OA who had received a 6-month physiotherapist-delivered VLED weight loss and exercise intervention. Questionnaires measured participant satisfaction and perceptions about physiotherapist's skills/knowledge in delivery of the dietary intervention (measured on 5-7 point Likert scales). Interviews explored participant's experiences and were analyzed based on the principles of reflexive thematic analysis.

RESULTS

Questionnaire response: 90%. Participants were satisfied with the program (95%), confident their physiotherapist had the required skills (84%) and knowledge (79%) to deliver the dietary intervention, felt comfortable talking to the physiotherapist about weight (74%), and would recommend others see a physiotherapist for the intervention they undertook (71%). The following four themes were developed from the interviews: (1) one-stop-shop of exercise and diet; (2) physiotherapist-delivered weight loss works (unsure initially; successfully lost weight); (3) physiotherapists knowledge and skills (exercise is forte; most thought physiotherapists had the necessary weight loss skills/knowledge, but some disagreed); and (4) physiotherapists have a role in weight loss (physiotherapists are intelligent, credible, and trustworthy; specific training in weight loss necessary).

CONCLUSION

This study provides, to our knowledge, the first documented perspectives from people with OA who have received a physiotherapist-delivered weight loss intervention. Findings suggest physiotherapists may have a role in delivering a protocolized dietary intervention for some people with knee OA with overweight and obesity.

Ketogenic Diet: A Review of Composition Diversity, Mechanism of Action and Clinical Application

The ketogenic diet (KD) is a special high-fat, very low-carbohydrate diet with the amount of protein adjusted to one's requirements. By lowering the supply of carbohydrates, this diet induces a considerable change in metabolism (of protein and fat) and increases the production of ketone bodies. The purpose of this article is to review the diversity of composition, mechanism of action, clinical application and risk associated with the KD. In the last decade, more and more results of the diet's effects on obesity, diabetes and neurological disorders, among other examples have appeared. The beneficial effects of the KD on neurological diseases are related to the reconstruction of myelin sheaths of neurons, reduction of neuron inflammation, decreased production of reactive oxygen species, support of dopamine production, repair of damaged mitochondria and formation of new ones. Minimizing the intake of carbohydrates results in the reduced absorption of simple sugars, thereby decreasing blood glucose levels and fluctuations of glycaemia in diabetes. Studies on obesity indicate an advantage of the KD over other diets in terms of weight loss. This may be due to the upregulation of the biological activity of appetite-controlling hormones, or to decreased lipogenesis, intensified lipolysis and increased metabolic costs of gluconeogenesis. However, it is important to be aware of the side effects of the KD. These include disorders of the digestive system as well as headaches, irritability, fatigue, the occurrence of vitamin and mineral deficiencies and worsened lipid profile. Further studies aimed to determine long-term effects of the KD are required.

A multiphase very-low calorie ketogenic diet improves serum redox balance by reducing oxidative status in obese patients

The very-low calorie ketogenic diet (VLCKD) is recommended as an effective dietary approach for the management of obesity. This study investigated changes in circulating biomarkers of redox homeostasis induced by a multiphase VLCKD in obese individuals. A total of 40 obese subjects were prescribed a multiphasic VLCKD for eleven weeks. Anthropometric measurements, body composition parameters, calorimetric measures, and standard laboratory markers of glucose and lipid metabolism were evaluated at baseline (T0) and at the end of the dietary intervention (T1). Additionally, circulating markers of oxidative damage and antioxidant status were analyzed in serum and erythrocytes. Compared to T0, at T1 the multiphase VLCKD induced significant weight loss and reduction of waist circumference, with beneficial effects on body composition parameters and the glucose/lipid biochemical profile. Moreover, a decrease in serum markers of oxidative damage was reported at T1, while no changes in serum markers of antioxidant status and in erythrocyte redox markers were observed. In addition, a significant association was found between variations in anthropometric measurements, body composition, glucose metabolism parameters, and changes in circulating markers of oxidative damage. Regression models showed that variation in lipofuscin was significant predictor of changes in body mass index, fat mass, visceral adiposity, and insulin sensitivity. In conclusion, this study demonstrated that the multiphase VLCKD improves serum redox balance by reducing markers of oxidative damage in obese individuals, highlighting the interplay between adiposity, glucose metabolism, and redox homeostasis in the pathogenesis of obesity. Furthermore, these data provide a rationale for future investigations aimed at testing serum lipofuscin as a reliable redox marker in obesity.

Acute effect of an exogenous ketone monoester supplement on appetite and food intake in adults with type 2 diabetes

The effects of exogenous ketones on appetite and food intake remain elusive, especially for people with type 2 diabetes (T2D). This study aimed to determine whether acute ingestion of an oral ketone monoester supplement (KME) affected appetite sensations, prospective food consumption and intake in T2D. Results showed that acute KME ingestion did not significantly alter appetite scores. However, there was a tendency for lower energy intake during an ad libitum meal 3 h following ketone ingestion compared to non-energetic placebo. Further research is warranted to understand the long-term effects of exogenous ketones for energy and macronutrient intake in T2D.

The gut microbiota changed by ketogenic diets contribute to glucose intolerance rather than lipid accumulation

The ketogenic diet (KD) is a popular option for managing body weight, though its influence on glucose and lipid metabolism was still inconclusive. Gut microbiota is modulated by dietary pattens and has been associated with the changes of metabolic homeostasis induced by KD. Here, we found that two types of KDs, KD1 (8.8% carbohydrate, 73.4% fat, 17.9% protein, 5.7 kcal/g) and KD2 (0.4% carbohydrate, 93.2% fat, 6.4% protein, 6.7 kcal/g), induced changes of gut microbiota and its metabolites, contributing to glucose intolerance but not lipid accumulation in mice. Following a 2-week intervention with KDs, mice fed on KD1 displayed symptoms related to obesity, whereas KD2-fed mice exhibited a decrease in body weight but had severe hepatic lipid accumulation and abnormal fatty acid metabolism, while both KDs led to significant glucose intolerance. Compared to the mice fed on a standard chow diet, the conventional mice fed on both KD1 and KD2 had significant shifted gut microbiota, lower levels of short chain fatty acids (SCFAs) and composition alteration of cecal bile acids. By using an antibiotic cocktail (ABX) to deplete most of the gut microbiota in mice, we found the disturbances induced by KDs in lipid metabolism were similar in the ABX-treated mice to their conventional companions, but the disturbances in glucose metabolism were absent in the ABX-treated mice. In conclusion, these findings suggest that ketogenic diets disrupted glucose and lipid metabolism, at least in mice, and highlight the gut microbial culprits associated with KD induced glucose intolerance rather than lipid accumulation.

The latest evidence and clinical guidelines for use of meal replacements in very-low-calorie diets or low-calorie diets for the treatment of obesity

Obesity is a complex chronic disease with increasing prevalence across the globe. Medical nutrition therapy (MNT) is an important component of obesity treatment, and low-calorie diets (LCDs) and very-low-calorie diets (VLCDs) are part of the MNT toolbox. This narrative review focuses on the latest evidence and clinical guidelines regarding the use and impact of meal replacements (MRs) as part of LCDs/VLCDs for the treatment of obesity and some associated complications. MRs can be used in conjunction with food as partial diet replacement (PDR) or can be used exclusively to serve as the sole source of dietary energy (total diet replacement [TDR]). Use of MR may be associated with better control of cravings and hunger typically observed during reduced calorie intake through effects of ketosis or stimuli narrowing, although the exact mechanisms for these effects remain unclear. Several clinical guidelines have endorsed the use of MRs as a part of MNT for obesity, primarily based on evidence that shows an average weight reduction of ~10 kg or more with TDR over at least 12 months in large, randomized controlled trials. When compared to usual care controls, these effects are 6-8 kg greater, and when compared to food-based diets, the effects are nearly twice the effect of a food-based diet. MR-based diets have been found to be safe and associated with improvements in quality of life. These diets are also effective for improving key cardiometabolic health outcomes, including dysglycaemia, blood pressure, lipids, and metabolic associated fatty liver. The effectiveness, safety, and associated health improvement makes MRs use a valuable strategy for several higher risk clinical scenarios where weight reduction is indicated.

Rethinking weight loss treatments as cardiovascular medicine in obesity, a comprehensive review

The global escalation of obesity has made it a worldwide health concern, notably as a leading risk factor for cardiovascular disease (CVD). Extensive evidence corroborates its association with a range of cardiac complications, including coronary artery disease, heart failure, and heightened vulnerability to sudden cardiac events. Additionally, obesity contributes to the emergence of other cardiovascular risk factors including dyslipidaemia, type 2 diabetes, hypertension, and sleep disorders, further amplifying the predisposition to CVD. To adequately address CVD in patients with obesity, it is crucial to first understand the pathophysiology underlying this link. We herein explore these intricate mechanisms, including adipose tissue dysfunction, chronic inflammation, immune system dysregulation, and alterations in the gut microbiome.Recent guidelines from the European Society of Cardiology underscore the pivotal role of diagnosing and treating obesity to prevent CVD. However, the intricate relationship between obesity and CVD poses significant challenges in clinical practice: the presence of obesity can impede accurate CVD diagnosis while optimizing the effectiveness of pharmacological treatments or cardiac procedures requires meticulous adjustment, and it is crucial that cardiologists acknowledge the implications of excessive weight while striving to enhance outcomes for the vulnerable population affected by obesity. We, therefore, sought to overcome controversial aspects in the clinical management of heart disease in patients with overweight/obesity and present evidence on cardiometabolic outcomes associated with currently available weight management interventions, with the objective of equipping clinicians with an evidence-based approach to recognize and address CVD risks associated with obesity.

Do people with type 2 diabetes find continuous and intermittent low-energy diets for weight loss and diabetes remission acceptable?

BACKGROUND

The Manchester Intermittent versus Daily Diet App Study (MIDDAS) tested the feasibility and potential efficacy of two remotely delivered low-energy diet (LED) programmes (800 kcal/day) to support weight loss and remission of type 2 diabetes: continuous [CLED] (8 weeks of daily LED) and intermittent [ILED] (2 days of LED/week for 28 weeks). Understanding participant experiences can help us to understand the acceptability of LED programmes to people with type 2 diabetes, informing future programme development and implementation.

METHODS

Twenty participants (10 CLED; 10 ILED) took part in interviews conducted at the end of the active weight loss phase (CLED week 12, ILED week 28). Interviews were transcribed and analysed thematically using the template analysis approach, with an a priori focus on acceptability. Four themes are presented: prospective acceptability, intervention coherence and perceived effectiveness, opportunity costs and self-efficacy.

RESULTS

Both remotely supported CLED and ILED interventions appeared acceptable to participants. CLED participants found the rapid initial weight loss phase comparatively easy and highly motivating but expressed more concerns around weight maintenance. ILED participants found the more gradual weight loss initially frustrating but expressed greater confidence in their longer-term adherence. The importance of continued individualised support from healthcare professionals was emphasised, and evidence of weight loss and improvement in other medical markers through monitoring via the mobile phone app was useful.

CONCLUSION

Different approaches to remotely delivered LEDs appear acceptable; therefore asking patients which approach may be more acceptable to them may be a useful way to offer individualised and tailored support.

Adaptive thermogenesis, at the level of resting energy expenditure, after diet alone or diet plus bariatric surgery

OBJECTIVE

The objective of this study was to compare the magnitude of adaptive thermogenesis (AT), at the level of resting energy expenditure (REE), after a very low-energy diet alone or combined with Roux-en-Y gastric bypass or sleeve gastrectomy, as well as to investigate the association between AT and changes in appetite.

METHODS

A total of 44 participants with severe obesity underwent 10 weeks of a very low-energy diet alone or combined with Roux-en-Y gastric bypass or sleeve gastrectomy. Body weight and composition, REE, subjective appetite feelings, and plasma concentrations of gastrointestinal hormones were measured at baseline and week 11. AT, at the level of REE, was defined as a significantly lower measured versus predicted (using a regression model with baseline data) REE.

RESULTS

Participants lost 18.4 ± 3.9 kg of body weight and experienced AT, at the level of REE (-121 ± 188 kcal/day; p < 0.001), with no differences among groups. The larger the AT, at the level of REE, the greater the reduction in fasting ghrelin concentrations and the smaller the reduction in feelings of hunger and desire to eat in the postprandial state.

CONCLUSIONS

Weight-loss modality does not seem to modulate the magnitude of AT, at the level of REE. The greater the AT, at the level of REE, the greater the drive to eat following weight loss.

Effects of Early and Late Time-Restricted Feeding on Parameters of Metabolic Health: An Explorative Literature Assessment

Chrono-nutrition (meal timing) aligns food consumption with one's circadian rhythm. The first meal (e.g., breakfast) likely promotes synchronization of peripheral circadian clocks, thereby supporting metabolic health. Time-restricted feeding (TRF) has been shown to reduce body weight (BW) and/or improve cardiovascular biomarkers. In this explorative literature assessment, 13 TRF randomized controlled trials (RCTs) were selected from PubMed and Scopus to evaluate the effects of early (eTRF: first meal before 10:30 a.m.) and late TRF (lTRF: first meal after 11:30 a.m.) on parameters of metabolic health. Although distinct variations in study design were evident between reports, TRF consistently decreased energy intake (EI) and BW, and improved insulin resistance as well as systolic blood pressure. eTRF seemed to have a greater beneficial effect than lTRF on insulin resistance (HOMA-IR). Importantly, most studies did not appear to consider chronotype in their evaluation, which may have underestimated TRF effects. TRF intervention may be a promising approach for risk reduction of human metabolic diseases. To conclusively determine benefits of TRF and identify clear differences between eTRF and lTRF, future studies should be longer-term (≥8 weeks) with well-defined (differences in) feeding windows, include participants chronotypically matching the intervention, and compare outcomes to those of control groups without any dietary limitations.

Effect of Ketogenic Diet on Obesity and Other Metabolic Disorders: Narrative Review

Obesity is defined as an abnormal or excessive accumulation of fat that increases the burden of different chronic diseases in the population. It has reached epidemic proportions and is a major risk factor for a variety of diseases, including hypertension, cardiovascular disease, type 2 diabetes, dyslipidaemia, atherosclerosis, and some malignancies. Weight gain is a result of excessive energy intake compared to energy expenditure (energy loss from metabolism and physical exercise). A ketogenic diet has a more useful effect on obesity than other diets. A ketogenic diet is a low-carbohydrate, high-fat, moderate-protein diet that induces the production of ketone bodies by mimicking the breakdown of a fasting state. The mechanism behind the ketogenic diet is still unknown, although it obviously helps people with obesity lose weight. Several pathways for the ketogenic diet effect on weight loss have been hypothesized by researchers, including reduced appetite due to effects on appetite control hormones and a possible direct appetite suppressant action of ketone bodies; reduced lipogenesis and increased lipolysis; greater metabolic efficiency; and increased metabolic costs.

Ketogenic diet combined with intermittent fasting: an option for type 2 diabetes remission?

With increasing attention to diabetes remission, various special dietary patterns have been found to be effective in achieving diabetes remission. The effect of a single dietary pattern on lowering blood glucose is clear, but studies on the synergistic effects of different dietary patterns are limited. This article describes the types of intermittent fasting and ketogenic diets, potential mechanisms, contraindications of combination diets, recommendations for combination diets, and their health outcomes. This paper aims to illustrate the evidence for intermittent fasting combined with a ketogenic diet on outcomes of diabetes remission and effect on blood glucose control. Knowledge of these findings can help doctors and patients determine dietary patterns for achieving diabetes remission and understanding their application.

Effectiveness of a telehealth-delivered clinician-supported exercise and weight loss program for hip osteoarthritis - protocol for the Better Hip randomised controlled trial

BACKGROUND

Hip osteoarthritis (OA) is a leading cause of chronic pain and disability worldwide. Self-management is vital with education, exercise and weight loss core recommended treatments. However, evidence-practice gaps exist, and service models that increase patient accessibility to clinicians who can support lifestyle management are needed. The primary aim of this study is to determine the effectiveness of a telehealth-delivered clinician-supported exercise and weight loss program (Better Hip) on the primary outcomes of hip pain on walking and physical function at 6 months, compared with an information-only control for people with hip OA.

METHODS

A two-arm, parallel-design, superiority pragmatic randomised controlled trial. 212 members from a health insurance fund aged 45 years and over, with painful hip OA will be recruited. Participants will be randomly allocated to receive: i) Better Hip; or ii) web-based information only (control). Participants randomised to the Better Hip program will have six videoconferencing physiotherapist consultations for education about OA, prescription of individualised home-based strengthening and physical activity programs, behaviour change support, and facilitation of other self-management strategies. Those with a body mass index > 27 kg/m2, aged < 80 years and no specific health conditions, will also be offered six videoconferencing dietitian consultations to undertake a weight loss program. Participants in the control group will be provided with similar educational information about managing hip OA via a custom website. All participants will be reassessed at 6 and 12 months. Primary outcomes are hip pain on walking and physical function. Secondary outcomes include measures of pain; hip function; weight; health-related quality of life; physical activity levels; global change in hip problem; willingness to undergo hip replacement surgery; rates of hip replacement; and use of oral pain medications. A health economic evaluation at 12 months will be conducted and reported separately.

DISCUSSION

Findings will determine whether a telehealth-delivered clinician-supported lifestyle management program including education, exercise/physical activity and, for those with overweight or obesity, weight loss, is more effective than information only in people with hip OA. Results will inform the implementation of such programs to increase access to core recommended treatments.

TRIAL REGISTRATION

Australia New Zealand Clinical Trials Registry (ACTRN12622000461796).

Metabolic adaptation is associated with a greater increase in appetite following weight loss: a longitudinal study

BACKGROUND

Weight loss is associated with a disproportionate reduction in energy expenditure, along with increases in hunger feelings and ghrelin concentrations. These changes are presumed to be homeostatic mechanisms to counteract the energy deficit. The possibility that these 2 components of the energy balance equation are mechanistically linked has never been examined.

OBJECTIVE

This study aimed to determine if the disproportionate reduction in resting metabolic rate (RMR) seen with weight loss is associated with changes in the plasma concentration of gastrointestinal hormones involved in appetite regulation and subjective appetite ratings.

METHODS

This was a longitudinal study with repeated measurements. Fifty-six individuals with obesity (body mass index [BMI]: 34.5±0.5 kg/m2; age: 47±1 y; 26 males) underwent an 8 wk low-energy diet, followed by 4 wk of refeeding and weight stabilization. The RMR, respiratory quotient (RQ), body composition, plasma concentrations of ghrelin, glucagon-like peptide 1, peptide YY, cholecystokinin, insulin, and appetite ratings in the fasting and postprandial states were measured at baseline, Wk9 and 13. Metabolic adaptation was defined as significantly lower when measured versus the predicted RMR (pRMR) (from own regression model using baseline data).

RESULTS

A 14.2±0.6 kg weight loss was seen at Wk9 and maintained at Wk13. RQ was significantly reduced at Wk9 (0.82±0.06 vs. 0.76±0.05, P< 0.001) but returned to baseline at Wk13. Metabolic adaptation was seen at Wk9, but not Wk13 (-341±58, P <0.001 and -75±72 kJ/d, P = 0.305, respectively). The larger the difference between measured and predicted RMR at both timepoints, the greater the increase in hunger, desire to eat, and composite appetite score (fasting and postprandial at Wk9, postprandial only at Wk13), even after adjusting for weight loss and RQ.

CONCLUSION

A larger metabolic adaptation during weight loss is accompanied by a greater drive to eat. This might help explain the interindividual differences in weight loss outcomes to dietary interventions.

Impact of the ketogenic diet on body fat, muscle mass, and exercise performance: a review

PURPOSE

The purpose of this review was to investigate the effects of the ketogenic diet (KD), on body fat, muscle mass, and exercise performance. As the KD is a subject of ongoing debate, we also present the existing evidence regarding its potential benefits in the aforementioned areas of body fat, muscle mass, and exercise performance.

METHODS

A literature search was conducted using the keywords "ketogenic diet, low-carbohydrate diet, high-fat diet, body fat, muscle mass, and exercise performance" in PubMed, Web of Science, and Google Scholar.

RESULTS

The KD effectively reduced body fat in the short term and, preserved muscle mass during weight loss, however, its impact on exercise performance remains inconclusive owing to various factors.

CONCLUSION

While controversial, it is undeniable that the KD has the potential to affect body fat, muscle mass, and exercise performance. Consequently, additional research is required to elucidate the underlying mechanisms across various populations, optimize their implementation, and understand their long-term effects.

Our biology working against us in obesity: A narrative review on implications for management of osteoarthritis

Obesity is the major modifiable risk factor for osteoarthritis (OA). A major focus of management in OA is weight loss. Although we live in an obesogenic environment, obesity has a predominantly genetic and epigenetic basis. This explains a person's weight set point which is defended by biological mechanisms making weight loss difficult to achieve and maintain long term, regardless of the methods used. Significant weight regain occurs after weight loss, with weight tending to return to pre-treatment levels after cessation of interventions including the glucagon-like peptide-1 (GLP-1) agonists. An area that has received little attention is the slow, insidious weight creep of 0.5-1 kg/year over adulthood that sees individuals relentlessly increase weight. There is evidence that low intensity, personalised lifestyle interventions can prevent this weight creep, providing patients with achievable goals. In this narrative review, we examine the evidence for weight loss in OA, the biological mechanisms that make weight loss difficult to achieve and maintain and the potential negative impacts on patients. We review the evidence for preventing weight gain, the improvement in patient outcomes and the potential for significant healthcare savings through reduced knee replacements. We propose a combined approach of weight loss when indicated, together with targeting weight creep across adult years and the potential role of metformin. Implementing these combined approaches is likely to be more effective in improving patient related outcomes, reducing joint damage and healthcare costs, than our current focus on achieving weight loss in OA.

Tolerability and Acceptability of an Exogenous Ketone Monoester and Ketone Monoester/Salt Formulation in Humans

Exogenous ketone ester and ketone ester mixed with ketone free acid formulations are rapidly entering the commercial marketspace. Short-term animal and human studies using these products suggest significant potential for primary or secondary prevention of a number of chronic disease conditions. However, a number of questions need to be addressed by the field for optimal use in humans, including variable responses among available exogenous ketones at different dosages; frequency of dosing; and their tolerability, acceptability, and efficacy in long-term clinical trials. The purpose of the current investigation was to examine the tolerability, acceptability, and circulating R-beta-hydroxybutyrate (R-βHB) and glucose responses to a ketone monoester (KME) and ketone monoester/salt (KMES) combination at 5 g and 10 g total R-βHB compared with placebo control (PC). Fourteen healthy young adults (age: 21 ± 2 years, weight: 69.7 ± 14.2 kg, percent fat: 28.1 ± 9.3%) completed each of the five study conditions: placebo control (PC), 5 g KME (KME5), 10 g KME (KME10), 5 g (KMES5), and 10 g KMES (KMES10) in a randomized crossover fashion. Circulating concentrations of R-βHB were measured at baseline (time 0) following an 8-12 h overnight fast and again at 15, 30, 60, and 120 min following drink ingestion. Participants also reported acceptability and tolerability during each condition. Concentrations of R-βHB rose to 2.4 ± 0.1 mM for KME10 after 15 min, whereas KMES10 similarly peaked (2.1 ± 0.1 mM) but at 30 min. KME5 and KMES5 achieved similar peak R-βHB concentrations (1.2 ± 0.7 vs. 1.1 ± 0.5 mM) at 15 min. Circulating R-βHB concentrations were similar to baseline for each condition by 120 min. Negative correlations were observed between R-βHB and glucose at the 30 min time point for each condition except KME10 and PC. Tolerability was similar among KME and KMES, although decreases in appetite were more frequently reported for KMES. Acceptability was slightly higher for KMES due to the more frequently reported aftertaste for KME. The results of this pilot investigation illustrate that the KME and KMES products used increase circulating R-βHB concentrations to a similar extent and time course in a dose-dependent fashion with slight differences in tolerability and acceptability. Future studies are needed to examine variable doses, frequency, and timing of exogenous ketone administration for individuals seeking to consume ketone products for health- or sport performance-related purposes.

Feasibility and impact of ketogenic dietary interventions in polycystic kidney disease: KETO-ADPKD-a randomized controlled trial

Ketogenic dietary interventions (KDIs) are beneficial in animal models of autosomal-dominant polycystic kidney disease (ADPKD). KETO-ADPKD, an exploratory, randomized, controlled trial, is intended to provide clinical translation of these findings (NCT04680780). Sixty-six patients were randomized to a KDI arm (ketogenic diet [KD] or water fasting [WF]) or the control group. Both interventions induce significant ketogenesis on the basis of blood and breath acetone measurements. Ninety-five percent (KD) and 85% (WF) report the diet as feasible. KD leads to significant reductions in body fat and liver volume. Additionally, KD is associated with reduced kidney volume (not reaching statistical significance). Interestingly, the KD group exhibits improved kidney function at the end of treatment, while the control and WF groups show a progressive decline, as is typical in ADPKD. Safety-relevant events are largely mild, expected (initial flu-like symptoms associated with KD), and transient. Safety assessment is complemented by nuclear magnetic resonance (NMR) lipid profile analyses.

How Does Exercise, With and Without Diet, Improve Pain and Function in Knee Osteoarthritis? A Secondary Analysis of a Randomized Controlled Trial Exploring Potential Mediators of Effects

OBJECTIVE

To explore the mediators of effects of two 6-month telehealth-delivered exercise programs, including exercise with and without weight-loss diet, on pain and function improvements in knee osteoarthritis (OA).

METHODS

Secondary analysis of 345 participants from a 3-arm randomized controlled trial of exercise (Exercise program) and exercise plus diet (Diet + Exercise program) versus information (Control program) was conducted. Outcomes were changes in pain (11-point numeric rating scale) and function (Western Ontario and McMaster Universities Osteoarthritis Index [score range 0-68]) at 12 months. Potential mediators were change at 6 months in attitudes toward self-management, fear of movement, arthritis self-efficacy, weight, physical activity, and willingness for knee surgery. For the Diet + Exercise program versus the Exercise program, only change in weight was evaluated.

RESULTS

Possible mediators of the Exercise program versus the Control program included reduced fear of movement (accounting for -1.11 units [95% confidence interval (95% CI) -2.15, -0.07] improvement in function) and increased arthritis self-efficacy (-0.40 units [95% CI -0.75, -0.06] reduction in pain, -1.66 units [95% CI -3.04, -0.28] improvement in function). The Diet + Exercise program versus the Control program mediators included reduced fear of movement (-1.13 units [95% CI -2.17, -0.08] improvement in function), increased arthritis self-efficacy (-0.77 units [95% CI -1.26, -0.28] reduction in pain, -5.15 units [95% CI -7.34, -2.96] improvement in function), and weight loss (-1.20 units [95% CI -1.73, -0.68] reduction in pain, -5.79 units [95% CI -7.96, -3.63] improvement in function). Weight loss mediated the Diet + Exercise program versus the Exercise program (-0.89 units [95% CI -1.31, -0.47] reduction in pain, -4.02 units [95% CI -5.77, -2.26] improvement in function).

CONCLUSION

Increased arthritis self-efficacy, reduced fear of movement, and weight loss may partially mediate telehealth-delivered exercise program effects, with and without diet, on pain and/or function in knee OA. Weight loss may partially mediate the effect of diet and exercise compared to exercise alone.

Metabolic shift toward ketosis in asocial cavefish increases social-like affinity

BACKGROUND

Social affinity and collective behavior are nearly ubiquitous in the animal kingdom, but many lineages feature evolutionarily asocial species. These solitary species may have evolved to conserve energy in food-sparse environments. However, the mechanism by which metabolic shifts regulate social affinity is not well investigated.

RESULTS

In this study, we used the Mexican tetra (Astyanax mexicanus), which features riverine sighted surface (surface fish) and cave-dwelling populations (cavefish), to address the impact of metabolic shifts on asociality and other cave-associated behaviors in cavefish, including repetitive turning, sleeplessness, swimming longer distances, and enhanced foraging behavior. After 1 month of ketosis-inducing ketogenic diet feeding, asocial cavefish exhibited significantly higher social affinity, whereas social affinity regressed in cavefish fed the standard diet. The ketogenic diet also reduced repetitive turning and swimming in cavefish. No major behavioral shifts were found regarding sleeplessness and foraging behavior, suggesting that other evolved behaviors are not largely regulated by ketosis. We further examined the effects of the ketogenic diet via supplementation with exogenous ketone bodies, revealing that ketone bodies are pivotal molecules positively associated with social affinity.

CONCLUSIONS

Our study indicated that fish that evolved to be asocial remain capable of exhibiting social affinity under ketosis, possibly linking the seasonal food availability and sociality.

Short- and long-term effects of very low- and low-calorie ketogenic diets on metabolism and cardiometabolic risk factors: a narrative review

Worldwide obesity and cardiovascular diseases have encouraged the adoption of new and efficient dietary strategies. Among various proposed diets, ketogenic diets, both the very-low-calorie ketogenic diet (VLCKD) and the low-calorie ketogenic diet (LCKD), have been suggested in recent years as an effective nutritional approach for obesity management. The VLCKD and the LCKD are characterized by a low carbohydrate content (<50 g/day), 1-1.5 g of protein/kg of ideal body weight, less than 20-30 g of lipids, and a daily intake of about 800 calories for VLCKD and about 1200-1400 calories for LCKD. The purpose of our narrative review is to offer an overview of the most impactful studies in the scientific literature regarding VLCKD and LCKD to discuss their short- and long-term effects (less than 12 months and more than 12 months respectively) on weight loss, metabolic and cardiovascular aspects. Articles we focused on were cohort studies, case-control studies, cross-sectional studies, randomized controlled trials, and meta-analyses. Results indicate that VLCKD and LCKD could be helpful to ameliorate metabolic and cardiovascular risk factors such as weight loss, glucose, and cholesterol levels, both in the short and long term. Further research in this area may include more randomized controlled trials to gather more data.

The Influence of Ketogenic Diet on Gut Microbiota: Potential Benefits, Risks and Indications

The ketogenic diet (KD) restricts carbohydrate consumption, leading to an increase in ketone bodies, such as acetoacetate, β-hydroxybutyrate, and acetone, which are utilized as energy substrates. This dietary approach impacts several biochemical processes, resulting in improved clinical management of various disorders, particularly in childhood. However, the exact mechanisms underlying the efficacy of KD remain unclear. Interestingly, KD may also impact the gut microbiota, which plays a pivotal role in metabolism, nutrition, and the development of the immune and nervous systems. KD has gained popularity for its potential benefits in weight loss, blood sugar control, and certain neurological conditions. This narrative review sums up KD-related studies published over 30 years. While short-term studies have provided valuable insights into the effects of KD on the gut microbiota, persistent uncertainties surround its long-term efficacy and potential for inducing dysbiosis. The significant influence of KD on epigenetic mechanisms, intracellular pathways, and gut microbial composition underscores its potential as a therapeutic choice. However, a judicious consideration of the potential risks associated with the strict adherence to a low-carbohydrate, high-fat, and high-protein regimen over prolonged periods is imperative. As KDs gain popularity among the adolescent and young adult demographic for weight management, it becomes imperative to undertake additional research to comprehensively assess their impact on nutritional status and gut microbiota, ensuring a holistic and sustainable approach to medical nutrition.

The Effects of Ketogenic Diet on Insulin Sensitivity and Weight Loss, Which Came First: The Chicken or the Egg?

The ketogenic diet (KD) is, nowadays, considered an interesting nutritional approach for weight loss and improvement in insulin resistance. Nevertheless, most of the studies available in the literature do not allow a clear distinction between its effects on insulin sensitivity per se, and the effects of weight loss induced by KDs on insulin sensitivity. In this review, we discuss the scientific evidence on the direct and weight loss mediated effects of KDs on glycemic status in humans, describing the KD's biochemical background and the underlying mechanisms.

Association between ß-Hydroxybutyrate Plasma Concentrations after Hypocaloric Ketogenic Diets and Changes in Body Composition

BACKGROUND

Early studies show that ketogenic diets (KDs) lead to preferential loss of fat mass (FM), whereas preserving fat-free mass (FFM). Additionally, animal data support the anticatabolic effects of DL-3-hydroxybutyrate. From our knowledge, a potential association between ß-hydroxybutyrate (ßHB) plasma concentrations and changes in body composition has never been explored.

OBJECTIVES

The main aim of this analysis was to determine if ßHB plasma concentrations, following hypocaloric KDs, were associated with FM and FFM changes in men and women with obesity.

METHODS

Data from 199 individuals (BMI = 36.6 ± 4.3 kg/m2; age = 43.6 ± 9.8 y; 82 men) were collated from 3 weight loss studies employing common measures of body composition (air displacement plethysmography) and ßHB plasma concentration (ELISA). The association between ßHB and weight, FM and FFM loss (kg), and %FFM loss (%FFML) was investigated with Spearman correlation. Multivariable linear regression was used to determine if ßHB was a significant predictor of the changes in anthropometric variables, after adjusting for confounding factors.

RESULTS

ßHB was not associated with FFML (% or kg), but a weak positive association was seen with FM loss (r = 0.182, P = 0.01, n = 199) and a trend with weight loss (r = 0.128, P = 0.072, n = 199). ßHB was a significant predictor of both weight and FM loss (kg), after adjusting for age, sex, baseline BMI, and intervention study.

CONCLUSIONS

The magnitude of ketosis is not associated with FFM preservation. However, the higher the level of ketosis, the greater the weight and FM loss. Further studies are needed to confirm these findings and to explore the mechanisms involved. This trial was registered at clinicaltrials.gov identifier as NCT01834859, NCT04051190, NCT02944253.

Impact of one-day fasting, ketogenic diet or exogenous ketones on control of energy balance in healthy participants

BACKGROUND & AIMS

Oral ketone supplements may mimic the beneficial effects of endogenous ketones on energy metabolism as β-hydroxybutyrate has been proposed to increase energy expenditure and improve body weight regulation. Therefore, our objective was to compare the effects of a one-day isocaloric ketogenic diet, fasting and supplementation with ketone salts on energy expenditure and appetite perception.

METHODS

Eight healthy young adults (4 women, 4 men, age 24 ± 3 years, BMI 24.3 ± 3.1 kg/m²) participated in a randomized cross-over trial with four 24 h-interventions in a whole room indirect calorimeter at a physical activity level of 1.65: (i) total fasting (FAST), (ii) isocaloric ketogenic diet (3.1% energy from carbohydrates (CHO), KETO), (iii) isocaloric control diet (47.4% energy from CHO, ISO), and (iv) ISO supplemented with 38.7 g/d ketone salts (exogenous ketones, EXO). Effects on serum ketone levels (15 h-iAUC), energy metabolism (total energy expenditure, TEE; sleeping energy expenditure, SEE; macronutrient oxidation) and subjective appetite were measured.

RESULTS

Compared to ISO, ketone levels were considerably higher with FAST and KETO and little higher with EXO (all p > 0.05). Total and sleeping energy expenditure did not differ between ISO, FAST and EXO whereas KETO increased TEE (+110 ± 54 kcal/d vs. ISO, p < 0.05) and SEE (+201 ± 90 kcal/d vs. ISO, p < 0.05). CHO oxidation was slightly decreased with EXO compared to ISO (-48 ± 27 g/d, p < 0.05) resulting in a positive CHO balance (p < 0.05). No differences between the interventions were found for subjective appetite ratings (all p > 0.05).

CONCLUSION

A 24 h-ketogenic diet may contribute to maintain a neutral energy balance by increasing energy expenditure. Exogenous ketones in addition to an isocaloric diet did not improve regulation of energy balance.

CLINICAL TRIAL REGISTRATION

NCT04490226 https://clinicaltrials.gov/.

No Evidence That Circulating GLP-1 or PYY Are Associated with Increased Satiety during Low Energy Diet-Induced Weight Loss: Modelling Biomarkers of Appetite

Bariatric surgery and pharmacology treatments increase circulating glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), in turn promoting satiety and body weight (BW) loss. However, the utility of GLP-1 and PYY in predicting appetite response during dietary interventions remains unsubstantiated. This study investigated whether the decrease in hunger observed following low energy diet (LED)-induced weight loss was associated with increased circulating 'satiety peptides', and/or associated changes in glucose, glucoregulatory peptides or amino acids (AAs). In total, 121 women with obesity underwent an 8-week LED intervention, of which 32 completed an appetite assessment via a preload challenge at both Week 0 and Week 8, and are reported here. Visual analogue scales (VAS) were administered to assess appetite-related responses, and blood samples were collected over 210 min post-preload. The area under the curve (AUC_0-210), incremental AUC (iAUC_0-210), and change from Week 0 to Week 8 (∆) were calculated. Multiple linear regression was used to test the association between VAS-appetite responses and blood biomarkers. Mean (±SEM) BW loss was 8.4 ± 0.5 kg (-8%). Unexpectedly, the decrease in ∆AUC_0-210 hunger was best associated with decreased ∆AUC_0-210 GLP-1, GIP, and valine (p < 0.05, all), and increased ∆AUC_0-210 glycine and proline (p < 0.05, both). The majority of associations remained significant after adjusting for BW and fat-free mass loss. There was no evidence that changes in circulating GLP-1 or PYY were predictive of changes in appetite-related responses. The modelling suggested that other putative blood biomarkers of appetite, such as AAs, should be further investigated in future larger longitudinal dietary studies.

'The fact that I know I can do it is quite a motivator now': a qualitative study exploring experiences maintaining weight loss 6 months after completing a weight loss programme for knee osteoarthritis

OBJECTIVE

To explore experiences maintaining weight loss 6 months after completing a multicomponent weight loss programme for knee osteoarthritis.

DESIGN

Qualitative study based on an interpretivist paradigm and a phenomenological approach that was embedded within a randomised controlled trial.

SETTING

Semistructured interviews were conducted with participants 6 months after completing a 6-month weight loss programme (ACTRN12618000930280) involving a ketogenic very low calorie diet (VLCD), exercise and physical activity programme, videoconferencing consultations with a dietitian and physiotherapist, and provision of educational and behaviour change resources and meal replacement products. Interviews were audio recorded, transcribed verbatim and data were analysed based on the principles of reflexive thematic analysis.

PARTICIPANTS

20 people with knee osteoarthritis.

RESULTS

Three themes were developed: (1) successfully maintained weight loss; (2) empowering self-management of weight (understand importance of exercise; increased knowledge about food and nutrition; resources from programme still useful; knee pain as a motivator; confidence in ability to self-regulate weight) and (3) challenges keeping on track (loss of accountability to dietitian and study; old habits and social situations; stressful life events or changes in health).

CONCLUSION

Participants had overall positive experiences maintaining their weight loss since completing the weight loss programme and were confident in their ability to self-regulate their weight in the future. Findings suggest a programme incorporating dietitian and physiotherapist consultations, a VLCD, and educational and behaviour change resources supports confidence maintaining weight loss in the medium term. Further research is required to explore strategies to overcome barriers like loss of accountability and returning to old eating habits.

Efficacy of low carbohydrate and ketogenic diets in treating mood and anxiety disorders: systematic review and implications for clinical practice

BACKGROUND

There is mounting interest in the potential efficacy of low carbohydrate and very low carbohydrate ketogenic diets in various neurological and psychiatric disorders.

AIMS

To conduct a systematic review and narrative synthesis of low carbohydrate and ketogenic diets (LC/KD) in adults with mood and anxiety disorders.

METHOD

MEDLINE, Embase, PsycINFO and Cochrane databases were systematically searched for articles from inception to 6 September 2022. Studies that included adults with any mood or anxiety disorder treated with a low carbohydrate or ketogenic intervention, reporting effects on mood or anxiety symptoms were eligible for inclusion. PROSPERO registration CRD42019116367.

RESULTS

The search yielded 1377 articles, of which 48 were assessed for full-text eligibility. Twelve heterogeneous studies (stated as ketogenic interventions, albeit with incomplete carbohydrate reporting and measurements of ketosis; diet duration: 2 weeks to 3 years; n = 389; age range 19 to 75 years) were included in the final analysis. This included nine case reports, two cohort studies and one observational study. Data quality was variable, with no high-quality evidence identified. Efficacy, adverse effects and discontinuation rates were not systematically reported. There was some evidence for efficacy of ketogenic diets in those with bipolar disorder, schizoaffective disorder and possibly unipolar depression/anxiety. Relapse after discontinuation of the diet was reported in some individuals.

CONCLUSIONS

Although there is no high-quality evidence of LC/KD efficacy in mood or anxiety disorders, several uncontrolled studies suggest possible beneficial effects. Robust studies are now needed to demonstrate efficacy, to identify clinical groups who may benefit and whether a ketogenic diet (beyond low carbohydrate) is required and to characterise adverse effects and the risk of relapse after diet discontinuation.

Association between fat-free mass loss, changes in appetite and weight regain in individuals with obesity

BACKGROUND

The role of fat-free mass loss (FFML) in modulating weight regain, in individuals with obesity, as well as the potential mechanisms involved, remain inconsistent.

AIMS

To determine if % FFML following weight loss (WL) is a predictor of weight regain, and to investigate the association between %FFML and changes in appetite markers.

METHODS

Seventy individuals with obesity (BMI: 36±4kg/m²; age: 44±9 years; 29 males) underwent 8 weeks of a very low-energy diet (550-660 kcal/day), followed by 4 weeks of gradual refeeding and weight stabilization, and a 9-month maintenance program (eucaloric diet). Body weight and body composition (fat mass (FM) and FFM) (primary outcomes), as well as ß-hydroxybutyrate (ßHB) plasma concentration (a marker of ketosis) in fasting and appetite-related hormones (ghrelin, glucagon-like peptide 1, peptide YY, and cholecystokinin) and subjective appetite feelings, in fasting and every 30 minutes after a fixed breakfast for 2.5h (secondary outcomes), were measured at baseline, week 9 and 1 year (and week 13 in 35 subjects (25 males)). The association between FFML, weight regain and changes in appetite was assessed by linear regression.

RESULTS

WL at week 9 was 17.5±4.3kg and %FFML 20.4±10.6%. Weight regain at 1 year was 1.7±8.2kg (8.8±45.0%). After adjusting for WL and FM at baseline, %FFML at week 9 was not a significant predictor of weight regain. Similar results were seen at week 13. The greater the %FFML at week 9, but not 13, the smaller the reduction, or greater the increase in basal ghrelin concentration (ß:-3.2; 95% CI: -5.0, -1.1; P=0.003), even after adjusting for WL and ß-hydroxybutyrate.

CONCLUSION

%FFML was not a significant predictor of weight regain at 1-year in individuals with obesity. However, a greater %FFML was accompanied by a greater increase in ghrelin secretion under ketogenic conditions, suggesting a link between FFM and appetite regulation.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT01834859.

Effect of d-β-Hydroxybutyrate-(R)-1,3 Butanediol on Appetite Regulation in People with Prediabetes

SCOPE

The main aim of the present study is to study the effect of acute ketosis on parameters of appetite regulation in prediabetes.

METHODS AND RESULTS

This is a randomized controlled trial registered under ClinicalTrials.gov identifier NCT03889210. After an overnight fast, 18 adults with prediabetes are assigned to consume a ketone monoester (d-β-hydroxybutyrate-(R)-1,3 butanediol) drink and a placebo drink in cross-over fashion. Blood samples are collected every 30 min, from baseline to 150 min. Paired t test is used to compare the total area under the curve (AUC) for the changes in parameters of appetite regulation (acylated ghrelin, peptide YY [PYY], and hunger) following both drinks. Significant elevation in blood β-hydroxybutyrate from 0.2 to 3.5 mmol L^-1 (p < 0.001) is achieved within 30 min. Acute ketosis does not result in statistically significant differences in the AUCs for ghrelin, PYY, and hunger.

CONCLUSION

Acute ketosis consistently does not affect both objective and subjective parameters of appetite regulation in prediabetes.

Gastrointestinal hormones and appetite ratings after weight loss induced by diet or bariatric surgery

OBJECTIVE

The aim of this study was to compare changes in gastrointestinal hormones and appetite ratings after a similar weight loss induced by a very low-energy diet alone or in combination with sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB).

METHODS

Patients with severe obesity scheduled for SG (n = 15) and RYGB (n = 14) and 15 controls (very low-energy diet alone) were recruited. Body weight/composition, plasma concentrations of ß-hydroxybutyric acid, acylated ghrelin, total glucagon-like peptide-1, total peptide YY, cholecystokinin, and ratings of hunger, fullness, desire to eat, and prospective food consumption were measured pre- and postprandially, before and after 10 weeks of intervention.

RESULTS

Changes in body weight/composition and level of ketosis were similar across groups. In SG and RYGB, basal and postprandial acylated ghrelin declined, and postprandial glucagon-like peptide-1 increased, both significantly more compared with controls. Postprandial peptide YY increased in all groups. Overall, postprandial hunger decreased, and postprandial fullness increased. But ratings of desire to eat and prospective food consumption were more favorable after both surgeries compared with controls.

CONCLUSIONS

Weight loss with SG and RYGB leads to more favorable changes in gastrointestinal hormones compared with diet alone, although ratings of appetite were reduced across all groups.

Relationship between Ketones, Ghrelin, and, Appetite on Isocaloric Diets with Varying Carbohydrate Quality and Amount: Results from a Randomized Controlled Trial in People with Obesity (CARBFUNC)

BACKGROUND

Low-carbohydrate high-fat (LCHF) diets may suppress the increase in appetite otherwise seen after diet-induced fat loss. However, studies of diets without severe energy restriction are lacking, and the effects of carbohydrate quality relative to quantity have not been directly compared.

OBJECTIVES

To evaluated short- (3 mo) and long-term (12 mo) changes in fasting plasma concentrations of total ghrelin, β-hydroxybutyrate (βHB), and subjective feelings of appetite on 3 isocaloric eating patterns within a moderate caloric range (2000-2500 kcal/d) and with varying carbohydrate quality or quantity.

METHODS

We performed a randomized controlled trial of 193 adults with obesity, comparing eating patterns based on "acellular" carbohydrate sources (e.g., flour-based whole-grain products; comparator arm), "cellular" carbohydrate sources (minimally processed foods with intact cellular structures), or LCHF principles. Outcomes were compared by an intention-to-treat analysis using constrained linear mixed modeling. This trial was registered at clinicaltrials.gov as NCT03401970.

RESULTS

Of the 193 adults, 118 (61%) and 57 (30%) completed 3 and 12 mo of follow-up. Throughout the intervention, intakes of protein and energy were similar with all 3 eating patterns, with comparable reductions in body weight (5%-7%) and visceral fat volume (12%-17%) after 12 mo. After 3 mo, ghrelin increased significantly with the acellular (mean: 46 pg/mL; 95% CI: 11, 81) and cellular (mean: 54 pg/mL; 95% CI: 21, 88) diets but not with the LCHF diet (mean: 11 pg/mL; 95% CI: -16, 38). Although βHB increased significantly more with the LCHF diet than with the acellular diet after 3 m (mean: 0.16 mmol/L; 95% CI: 0.09, 0.24), this did not correspond to a significant group difference in ghrelin (unless the 2 high-carbohydrate groups were combined [mean: -39.6 pg/mL; 95% CI: -76, -3.3]). No significant between-group differences were seen in feelings of hunger.

CONCLUSIONS

Modestly energy-restricted isocaloric diets differing in carbohydrate cellularity and amount showed no significant differences in fasting total ghrelin or subjective hunger feelings. An increase in ketones with the LCHF diet to 0.3-0.4 mmol/L was insufficient to substantially curb increases in fasting ghrelin during fat loss.

Influence of anti-obesity strategies on brain function in health and review: A review

The aim of this review was to investigate in the literature the application of strategies such as low carbohydrate diet (LCD), ketogenic diet (KD) and intermittent fasting (IF) and their effects on the CNS. We performed a narrative review of the literature. The search was specifically carried out in PubMed, selecting articles in English, which had the following keywords: obesity, central nervous system, low carb diet, ketogenic diet and intermittent fasting, using the narrative review methodology. The studies found show that the benefits of the LCD, KD and IF strategies, at the CNS level, have a strong influence on the mechanisms of hunger and satiety, as well as on the reduction of food reward and show improvement in memory and mood influenced by the interventions.

Levels of hormones regulating appetite and energy homeostasis in response to a 1.5-Year combined lifestyle intervention for obesity

Background: Weight loss can induce changes in appetite-regulating hormone levels, possibly linked to increases in appetite and weight regain. However, hormonal changes vary across interventions. Here, we studied levels of appetite-regulating hormones during a combined lifestyle intervention (CLI: healthy diet, exercise and cognitive behavioral therapy). Methods: We measured levels of long-term adiposity-related hormones (leptin, insulin, high-molecular-weight (HMW) adiponectin) and short-term appetite hormones (PYY, cholecystokinin, gastric-inhibitory polypeptide, pancreatic polypeptide, FGF21, AgRP) in overnight-fasted serum of 39 patients with obesity. Hormone levels were compared between T0 (baseline), T1 (after 10 weeks) and T2 (end of treatment, 1.5 years). T0-T1 hormone changes were correlated with T1-T2 anthropometric changes. Results: Initial weight loss at T1 was maintained at T2 (-5.0%, p < 0.001), and accompanied by decreased leptin and insulin levels at T1 and T2 (all p < 0.05) compared to T0. Most short-term signals were not affected. Only PP levels were decreased at T2 compared to T0 (p < 0.05). Most changes in hormone levels during initial weight loss did not predict subsequent changes in anthropometrics, except for T0-T1 decreases in FGF21 levels and T0-T1 increases in HMW adiponectin levels tended to be associated with larger T1-T2 increases in BMI (p < 0.05 and p = 0.05, respectively). Conclusion: CLI-induced weight loss was associated with changes in levels of long-term adiposity-related hormones towards healthy levels, but not with orexigenic changes in most short-term appetite signals. Our data indicates that the clinical impact of alterations in appetite-regulating hormones during modest weight loss remains questionable. Future studies should investigate potential associations of weight-loss-induced changes in FGF21 and adiponectin levels with weight regain.

Does exercise during a ketogenic diet effectively alter appetite sensation, appetite-regulating hormones, and body composition?

Exercise and diet are two essential interventions in weight control. The purpose of this study was to compare the effectiveness of two exercise training types during a ketogenic diet (KD) on appetite sensation, appetite-regulating hormones, and body composition in overweight or obese man. Thirty-six men, overweight or with obesity, voluntarily participated in this study. The participants were randomly assigned into three groups, including KD (n = 12), aerobic training during KD (AT-KD) (n = 12), and resistance training during KD (RT-KD) (n = 12) groups. The participants followed a low-carbohydrate diet for 6 weeks. Exercise training programs consisted of three sessions per week over 6 weeks. Appetite sensation was analyzed using a visual analogue scale (VAS) in fasting and postprandial states. The Enzyme-Linked Immunosorbent Assay (ELISA) method analyzed appetite-regulating hormones, including spexin, leptin, and acylated ghrelin, in a fasting state. Body composition was measured using bioelectrical impedance analysis (BIA). Furthermore, the ketosis state was monitored by measuring urinary ketones weekly. The results indicated that in both AT-KD and RT-KD groups, spexin and acylated ghrelin increased while leptin decreased without any between-group differences. Hunger and prospective food consumption (PFC) declined while satiety and fullness increased in all groups. The AT-KD group experienced a significant decrease in hunger and PFC, while fullness increased compared with the KD group. Fat mass, weight, and body mass index (BMI) decreased in all groups. Lean body mass increased in the RT-KD group (+2.66 kg) compared with both AT-KD and KD groups (-1.71 and -1.33 kg, respectively). This study demonstrated that AT-KD and RT-KD effectively altered appetite-regulating hormones and suppressed appetite sensation. In addition, both interventions had a favorable effect on weight loss and body fat reduction, with a more pronounced effect of RT-KD on maintaining lean body mass in overweight or obese men.

Unprocessed red meat in the dietary treatment of obesity: a randomized controlled trial of beef supplementation during weight maintenance after successful weight loss

BACKGROUND

Consumption of unprocessed red meat in randomized trials has no adverse effects on cardiovascular risk factors and body weight, but its physiological effects during weight loss maintenance are not known.

OBJECTIVES

We sought to investigate the effects of healthy diets that include small or large amounts of red meat on the maintenance of lost weight after successful weight loss, and secondarily on body composition (DXA), resting energy expenditure (REE; indirect calorimetry), and cardiometabolic risk factors.

METHODS

In this 5-mo parallel randomized intervention trial, 108 adults with BMI 28-40 kg/m2 (45 males/63 females) underwent an 8-wk rapid weight loss period, and those who lost ≥8% body weight (n = 80) continued to ad libitum weight maintenance diets for 12 wk: a moderate-protein diet with 25 g beef/d (B25, n = 45) or a high-protein diet with 150 g beef/d (B150, n = 35).

RESULTS

In per protocol analysis (n = 69), mean body weight (-1.2 kg; 95% CI: -2.1, -0.3 kg), mean fat mass (-2.7 kg; 95% CI: -3.4, -2.0 kg), and mean body fat content (-2.6%; 95% CI: -3.1, -2.1%) decreased during the maintenance phase, whereas mean lean mass (1.5 kg; 95% CI: 1.0, 2.0 kg) and mean REE (51 kcal/d; 95% CI: 15, 86 kcal/d) increased, with no differences between groups (all P > 0.05). Results were similar in intention-to-treat analysis with multiple imputation for dropouts (20 from B150 compared with 19 from B25, P = 0.929). Changes in cardiometabolic risk factors were not different between groups, the general pattern being a decrease during weight loss and a return to baseline during weight maintenance (and despite the additional mild reduction in weight and fat mass).

CONCLUSIONS

Healthy diets consumed ad libitum that contain a little or a lot of unprocessed beef have similar effects on body weight, energy metabolism, and cardiovascular risk factors during the first 3 mo after clinically significant rapid weight loss.

Using a Very Low Energy Diet to Achieve Substantial Preconception Weight Loss in Women with Obesity: A Review of the Safety and Efficacy

Obesity in women of reproductive age is common. Emerging evidence suggests that maternal obesity not only increases the risk of adverse pregnancy outcomes but also has an enduring impact on the metabolic health of the offspring. Given this, management of obesity prior to pregnancy is critically important. Almost all international guidelines suggest that women with obesity should aim to achieve weight loss prior to pregnancy. However, current pre-conception weight loss therapies are sub-optimal. Lifestyle modification typically results in modest weight loss. This may assist fertility but does not alter pregnancy outcomes. Bariatric surgery results in substantial weight loss, which improves pregnancy outcomes for the mother but may be harmful to the offspring. Alternative approaches to the management of obesity in women planning pregnancy are needed. Very low energy diets (VLEDs) have been proposed as a possible tool to assist women with obesity achieve weight loss prior to conception. While VLEDs can induce substantial and rapid weight loss, there are concerns about the impact of rapid weight loss on maternal nutrition prior to pregnancy and about inadvertent exposure of the early fetus to ketosis. The purpose of this review is to examine the existing literature regarding the safety and efficacy of a preconception VLED program as a tool to achieve substantial weight loss in women with obesity.

Italian Ketogenic Mediterranean Diet in Overweight and Obese Patients with Prediabetes or Type 2 Diabetes

Obesity is a multifactorial disease strongly associated with insulin resistance and/or type 2 diabetes mellitus. Correct nutrition represents a valid strategy to fight these dysmetabolic pathologies responsible for numerous diseases, including inflammatory and cardiovascular ones. Medical nutrition therapy, including a Mediterranean diet (MD) and a very low-calorie ketogenic diet (VLKCD), is the first-line treatment for prediabetes/diabetes and overweight/obesity. Eighty patients (forty women and forty men) affected by overweight/obesity and type 2 diabetes mellitus or impaired glucose tolerance or impaired fasting glucose (51 (ys) ± 1.75; BMI (kg/m2) 33.08 ± 1.93; HA1c (%): 6.8% ± 0.25) were enrolled at the University Service of Diet Therapy, Diabetology and Metabolic Diseases, Policlinico Riuniti Hospital of Foggia, and subjected to a very-low-calorie Mediterranean diet and a very-low-calorie ketogenic Mediterranean diet for thirty days. Both diets result in a marked decrease in body weight (kg) and BMI (kg/m2). At the same time, only the very-low-calories ketogenic Mediterranean diet reduced waist and hip circumferences. Both diets helped reduce fat mass, but a major loss was achieved in a very low-calorie ketogenic Mediterranean diet. Among gluco-metabolic parameters, only the very-low-calorie ketogenic Mediterranean diet group showed a significant decrease in fasting blood glucose and HbA1c, insulin, C-peptide total cholesterol, LDL, and triglycerides. The results of our study seem to show that the very-low-calorie ketogenic Mediterranean diet is a good strategy to improve rapidly metabolic, anthropometric, and body composition parameters in patients with prediabetes or diabetes and overweight/obesity.

Effects of a Low-Carbohydrate Dietary Intervention on Hemoglobin A1c: A Randomized Clinical Trial

IMPORTANCE

Low-carbohydrate diets decrease hemoglobin A1c (HbA1c) among patients with type 2 diabetes at least as much as low-fat diets. However, evidence on the effects of low-carbohydrate diets on HbA1c among individuals with HbA1c in the range of prediabetes to diabetes not treated by diabetes medications is limited.

OBJECTIVE

To study the effect of a behavioral intervention promoting a low-carbohydrate diet compared with usual diet on 6-month changes in HbA1c among individuals with elevated untreated HbA1c.

DESIGN, SETTING, AND PARTICIPANTS

This 6-month randomized clinical trial with 2 parallel groups was conducted from September 2018 to June 2021 at an academic medical center in New Orleans, Louisiana. Laboratory analysts were blinded to assignment. Participants were aged 40 to 70 years with untreated HbA1c of 6.0% to 6.9% (42-52 mmol/mol). Data analysis was performed from November 2021 to September 2022.

INTERVENTIONS

Participants were randomized to a low-carbohydrate diet intervention (target <40 net grams of carbohydrates during the first 3 months; <60 net grams for months 3 to 6) or usual diet. The low-carbohydrate diet group received dietary counseling.

MAIN OUTCOMES AND MEASURES

Six-month change in HbA1c was the primary outcome. Outcomes were measured at 0, 3, and 6 months.

RESULTS

Of 2722 prescreened participants, 962 underwent screening, and 150 were enrolled (mean [SD] age, 58.9 [7.9] years; 108 women [72%]; 88 Black participants [59%]) and randomized to either the low-carbohydrate diet intervention (75 participants) or usual diet (75 participants) group. Six-month data were collected on 142 participants (95%). Mean (SD) HbA1c was 6.16% (0.30%) at baseline. Compared with the usual diet group, the low-carbohydrate diet intervention group had significantly greater 6-month reductions in HbA1c (net difference, -0.23%; 95% CI, -0.32% to -0.14%; P < .001), fasting plasma glucose (-10.3 mg/dL; 95% CI, -15.6 to -4.9 mg/dL; P < .001), and body weight (-5.9 kg; 95% CI, -7.4 to -4.4 kg; P < .001).

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, a low-carbohydrate dietary intervention led to improvements in glycemia in individuals with elevated HbA1c not taking glucose-lowering medication, but the study was unable to evaluate its effects independently of weight loss. This diet, if sustained, might be a useful dietary approach for preventing and treating type 2 diabetes, but more research is needed.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03675360.

Dietary Risk Factors and Eating Behaviors in Peripheral Arterial Disease (PAD)

Dietary risk factors play a fundamental role in the prevention and progression of atherosclerosis and PAD (Peripheral Arterial Disease). The impact of nutrition, however, defined as the process of taking in food and using it for growth, metabolism and repair, remains undefined with regard to PAD. This article describes the interplay between nutrition and the development/progression of PAD. We reviewed 688 articles, including key articles, narrative and systematic reviews, meta-analyses and clinical studies. We analyzed the interaction between nutrition and PAD predictors, and subsequently created four descriptive tables to summarize the relationship between PAD, dietary risk factors and outcomes. We comprehensively reviewed the role of well-studied diets (Mediterranean, vegetarian/vegan, low-carbohydrate ketogenic and intermittent fasting diet) and prevalent eating behaviors (emotional and binge eating, night eating and sleeping disorders, anorexia, bulimia, skipping meals, home cooking and fast/ultra-processed food consumption) on the traditional risk factors of PAD. Moreover, we analyzed the interplay between PAD and nutritional status, nutrients, dietary patterns and eating habits. Dietary patterns and eating disorders affect the development and progression of PAD, as well as its disabling complications including major adverse cardiovascular events (MACE) and major adverse limb events (MALE). Nutrition and dietary risk factor modification are important targets to reduce the risk of PAD as well as the subsequent development of MACE and MALE.

Ketogenic Diet Benefits to Weight Loss, Glycemic Control, and Lipid Profiles in Overweight Patients with Type 2 Diabetes Mellitus: A Meta-Analysis of Randomized Controlled Trails

A ketogenic diet, characterized by low calories with high levels of fat, adequate levels of protein, and low levels of carbohydrates, has beneficial effects on body weight control in overweight patients. In the present study, a meta-analysis was conducted to investigate the role of a ketogenic diet in body weight control and glycemic management in overweight patients with type 2 diabetes mellitus (T2DM). In summary, we systematically reviewed articles from the Embase, PubMed, Web of Science and Cochrane Library databases and obtained eight randomized controlled trials for meta-analysis. The results show that a ketogenic diet had significantly beneficial effects on the loss of body weight (SMD, -5.63, p = 0.008), the reduction of waist circumference (SMD, -2.32, p = 0.04), lowering glycated hemoglobin (SMD, -0.38, p = 0.0008) and triglycerides (SMD, -0.36, p = 0.0001), and increasing high-density lipoproteins (SMD, 0.28, p = 0.003). Overall, these results suggest that a ketogenic diet may be an effective dietary intervention for body weight and glycemic control, as well as improved lipid profiles in overweight patients with T2DM. Hence, a ketogenic diet can be recommended for the therapeutic intervention of overweight patients with T2DM.

Effectiveness of a telehealth physiotherapist-delivered intensive dietary weight loss program combined with exercise in people with knee osteoarthritis and overweight or obesity: study protocol for the POWER randomized controlled trial

BACKGROUND

Obesity is associated with knee osteoarthritis (OA). Weight loss, alongside exercise, is a recommended treatment for individuals with knee OA and overweight/obesity. However, many patients cannot access weight loss specialists such as dietitians. Innovative care models expanding roles of other clinicians may increase access to weight loss support for people with knee OA. Physiotherapists may be well placed to deliver such support. This two-group parallel, superiority randomized controlled trial aims to compare a physiotherapist-delivered diet and exercise program to an exercise program alone, over 6 months. The primary hypothesis is that the physiotherapist-delivered diet plus exercise program will lead to greater weight loss than the exercise program.

METHODS

88 participants with painful knee OA and body mass index (BMI) > 27 kg/m² will be recruited from the community. Following baseline assessment, participants will be randomised to either exercise alone or diet plus exercise groups. Participants in the exercise group will have 6 consultations (20-30 min) via videoconference with a physiotherapist over 6 months for a strengthening exercise program, physical activity plan and educational/exercise resources. Participants in the diet plus exercise group will have 6 consultations (50-75 min) via videoconference with a physiotherapist prescribing a ketogenic very low-calorie diet with meal replacements and educational resources to support weight loss and healthy eating, plus the intervention of the exercise only group. Outcomes are measured at baseline and 6 months. The primary outcome is percentage change in body weight measured by a blinded assessor. Secondary outcomes include self-reported knee pain, physical function, global change in knee problems, quality of life, physical activity levels, and internalised weight stigma, as well as BMI, waist circumference, waist-to-hip ratio, physical performance measures and quadriceps strength, measured by a blinded assessor. Additional measures include adherence, adverse events, fidelity and process measures.

DISCUSSION

This trial will determine whether a physiotherapist-delivered diet plus exercise program is more effective for weight loss than an exercise only program. Findings will inform the development and implementation of innovative health service models addressing weight management and exercise for patients with knee OA and overweight/obesity.

TRIAL REGISTRATION

NIH US National Library of Medicine, Clinicaltrials.gov NCT04733053 (Feb 1 2021).

Citrate Synthase Insufficiency Leads to Specific Metabolic Adaptations in the Heart and Skeletal Muscles Upon Low-Carbohydrate Diet Feeding in Mice

A decrease in TCA cycle activity may lead to impaired nutrition metabolism and cellular energy shortage. Herein, we aimed to characterize the detailed metabolic changes that compensate for energy shortages in energy-consuming organs (heart and skeletal muscles) in mice with knockout of citrate synthase (CS), an important enzyme in the TCA cycle. CS hetero knockout (CS +/−) mice and wild-type mice were fed a low-carbohydrate ketogenic diet (LCKD) or high-fat, high-carbohydrate diet (HFHCD) to induce metabolic changes. Body weight, blood serum parameters, metabolic gene expression, and adenosine triphosphate (ATP) levels were measured in the heart and skeletal muscles. Glycogen content, anabolic and catabolic biomarkers, and morphological changes were also assessed in the skeletal muscles. After diet feeding, there were no differences observed in the body weight and blood serum parameters between wild-type and CS +/− mice. The cardiac expression of genes related to the utilization of fatty acids, monocarboxylates, and branched amino acids increased in LCKD-fed CS +/− mice. In contrast, no significant differences in gene expression were observed in the muscles of LCKD-fed mice or the heart and muscles of HFHCD-fed mice. ATP levels decreased only in the skeletal muscles of LCKD-fed CS +/− mice. Additionally, the decrease in glycogen content, suppression of p70 S6 kinase, and presence of type I fiber atrophy were observed in the muscles of LCKD-fed CS +/− mice. These results suggest that the energy-consuming organs with CS insufficiency may undergo tissue-specific adaption to compensate for energy shortages when the carbohydrate supply is limited.

Fad Diets: Facts and Fiction

The global prevalence of obesity is alarmingly high and is impacting both developed and underdeveloped countries, beyond the borders of ethnicity, sex, and age. On the other hand, the global interest in dieting has increased, and people are obsessed with certain fad diets, assuming them as a magic bullet for their long-term problems. A fad diet is a popular dietary pattern known to be a quick fix for obesity. These diets are quite appealing due to the proposed claims, but the lack of scientific evidence is a big question mark. Such diets are often marketed with specific claims that defy the basic principles of biochemistry and nutritional adequacy. These diets may have protective effects against obesity and certain chronic diseases like cardiovascular diseases, metabolic syndrome, and certain cancers. Limited evidence exists to support the proposed claims; rather certain studies suggest the negative health consequences of long-term adherence to such dietary patterns. Many fad diets have emerged in the previous few decades. This review article will explore the current evidence related to the health impacts of some most popular diets: Atkins diet, ketogenic diet, Paleolithic diet, Mediterranean diet, vegetarian diet, intermittent fasting and detox diet.

Helpful or harmful? The impact of the ketogenic diet on eating disorder outcomes in type 1 diabetes mellitus

INTRODUCTION

Eating disorders (EDs) are common complications in people with type 1 diabetes (PwT1D), given the rigid focus on food and insulin dose adjustment. Dietary recommendations for T1D match those for the general population, yet many fail to achieve target HbA1c. Evidence suggests that lower carbohydrate meals and thus reduced insulin requirements may decrease inconsistencies in insulin absorption, maintain euglycemia and weight. Dietary restriction is a recognized risk factor for ED development, and Ketogenic Diets (KD) involve restriction of common family-based foods, thus impacting social normality and microbiome diversity. We reviewed the current literature on PwT1D following a KD to understand effects on ED risks.

AREAS COVERED

Published data from MEDLINE, Embase, and PsycINFO were used. Search terms included: type 1 diabetes mellitus; or insulin dependent diabetes or T1D AND EDs or anorexia or bulimia or disordered eating AND low-carbohydrate diet or carbohydrate restricted diet or low carb diet or ketogenic diet.

EXPERT OPINION

Research into the effects of KDs on ED outcomes in PwT1D are limited, given the concerns over risks of diabetic ketoacidosis, hypoglycemia, and dyslipidemia. Longer term studies on the participants' experience and motivations of adhering or admonishing the diet are needed.

Ketogenic diets, physical activity and body composition: a review

Obesity remains a serious relevant public health concern throughout the world despite related countermeasures being well understood (i.e. mainly physical activity and an adjusted diet). Among different nutritional approaches, there is a growing interest in ketogenic diets (KD) to manipulate body mass (BM) and to enhance fat mass loss. KD reduce the daily amount of carbohydrate intake drastically. This results in increased fatty acid utilisation, leading to an increase in blood ketone bodies (acetoacetate, 3-β-hydroxybutyrate and acetone) and therefore metabolic ketosis. For many years, nutritional intervention studies have focused on reducing dietary fat with little or conflicting positive results over the long term. Moreover, current nutritional guidelines for athletes propose carbohydrate-based diets to augment muscular adaptations. This review discusses the physiological basis of KD and their effects on BM reduction and body composition improvements in sedentary individuals combined with different types of exercise (resistance training or endurance training) in individuals with obesity and athletes. Ultimately, we discuss the strengths and the weaknesses of these nutritional interventions together with precautionary measures that should be observed in both individuals with obesity and athletic populations. A literature search from 1921 to April 2021 using Medline, Google Scholar, PubMed, Web of Science, Scopus and Sportdiscus Databases was used to identify relevant studies. In summary, based on the current evidence, KD are an efficient method to reduce BM and body fat in both individuals with obesity and athletes. However, these positive impacts are mainly because of the appetite suppressive effects of KD, which can decrease daily energy intake. Therefore, KD do not have any superior benefits to non-KD in BM and body fat loss in individuals with obesity and athletic populations in an isoenergetic situation. In sedentary individuals with obesity, it seems that fat-free mass (FFM) changes appear to be as great, if not greater, than decreases following a low-fat diet. In terms of lean mass, it seems that following a KD can cause FFM loss in resistance-trained individuals. In contrast, the FFM-preserving effects of KD are more efficient in endurance-trained compared with resistance-trained individuals.