Personalized Dietary Management of Overweight and Obesity Based on Measures of Insulin and Glucose

Digital applications for diet monitoring, planning, and precision nutrition for citizens and professionals: a state of the art

The objective of this review was to critically examine existing digital applications, tailored for use by citizens and professionals, to provide diet monitoring, diet planning, and precision nutrition. We sought to identify the strengths and weaknesses of such digital applications, while exploring their potential contributions to enhancing public health, and discussed potential developmental pathways. Nutrition is a critical aspect of maintaining good health, with an unhealthy diet being one of the primary risk factors for chronic diseases, such as obesity, diabetes, and cardiovascular disease. Tracking and monitoring one's diet has been shown to help improve health and weight management. However, this task can be complex and time-consuming, often leading to frustration and a lack of adherence to dietary recommendations. Digital applications for diet monitoring, diet generation, and precision nutrition offer the promise of better health outcomes. Data on current nutrition-based digital tools was collected from pertinent literature and software providers. These digital tools have been designed for particular user groups: citizens, nutritionists, and physicians and researchers employing genetics and epigenetics tools. The applications were evaluated in terms of their key functionalities, strengths, and limitations. The analysis primarily concentrated on artificial intelligence algorithms and devices intended to streamline the collection and organization of nutrition data. Furthermore, an exploration was conducted of potential future advancements in this field. Digital applications designed for the use of citizens allow diet self-monitoring, and they can be an effective tool for weight and diabetes management, while digital precision nutrition solutions for professionals can provide scalability, personalized recommendations for patients, and a means of providing ongoing diet support. The limitations in using these digital applications include data accuracy, accessibility, and affordability, and further research and development are required. The integration of artificial intelligence, machine learning, and blockchain technology holds promise for improving the performance, security, and privacy of digital precision nutrition interventions. Multidisciplinarity is crucial for evidence-based and accessible solutions. Digital applications for diet monitoring and precision nutrition have the potential to revolutionize nutrition and health. These tools can make it easier for individuals to control their diets, help nutritionists provide better care, and enable physicians to offer personalized treatment.

Influence of Mediterranean Diet on Sexual Function in People with Metabolic Syndrome: A Narrative Review

Metabolic syndrome (MS), a cluster of cardiometabolic disorders, and sexual dysfunction are two conditions that impact a large proportion of the general population. Although they can occur independently, they are frequently linked and significantly affect people's quality of life. In recent years, research has increasingly focused on the importance of diet, particularly the Mediterranean diet (MD), in modulating sexual function due to its anti-inflammatory, antioxidant, and vasodilatory properties. In this narrative review, we examined the relationship between MS and sexual function in both men and women, with a special emphasis on the MD's therapeutic efficacy in improving sexual dysfunction. In men, MD has been shown to ameliorate erectile dysfunction, as well as several sperm parameters, perhaps leading to improved fertility. On the other hand, adherence to MD has been demonstrated to partially recover several sexual dysfunctions in women, such as those related to their menstrual cycle, menopause, endometriosis, and polycystic ovary syndrome. These favorable effects of MD have been demonstrated in both sexes also among people affected by MS. However, more targeted studies are needed to validate these data for different dietary approaches as well.

Nutritional Considerations During Major Weight Loss Therapy: Focus on Optimal Protein and a Low-Carbohydrate Dietary Pattern

PURPOSE OF REVIEW

Considering the high prevalence of obesity and related metabolic impairments in the population, the unique role nutrition has in weight loss, reversing metabolic disorders, and maintaining health cannot be overstated. Normal weight and well-being are compatible with varying dietary patterns, but for the last half century there has been a strong emphasis on low-fat, low-saturated fat, high-carbohydrate based approaches. Whereas low-fat dietary patterns can be effective for a subset of individuals, we now have a population where the vast majority of adults have excess adiposity and some degree of metabolic impairment. We are also entering a new era with greater access to bariatric surgery and approval of anti-obesity medications (glucagon-like peptide-1 analogues) that produce substantial weight loss for many people, but there are concerns about disproportionate loss of lean mass and nutritional deficiencies.

RECENT FINDINGS

No matter the approach used to achieve major weight loss, careful attention to nutritional considerations is necessary. Here, we examine the recent findings regarding the importance of adequate protein to maintain lean mass, the rationale and evidence supporting low-carbohydrate and ketogenic dietary patterns, and the potential benefits of including exercise training in the context of major weight loss. While losing and sustaining weight loss has proven challenging, we are optimistic that application of emerging nutrition science, particularly personalized well-formulated low-carbohydrate dietary patterns that contain adequate protein (1.2 to 2.0 g per kilogram reference weight) and achieve the beneficial metabolic state of euketonemia (circulating ketones 0.5 to 5 mM), is a promising path for many individuals with excess adiposity.

Is There an Ideal Diet? Some Insights from the POUNDS Lost Study

Diets for weight loss have a long history but an ideal one has not yet been clearly identified. To compare low-fat and lower carbohydrate diets, we designed The Preventing Overweight by Novel Dietary Strategies (POUNDS) Lost study. This is a 2 × 2 factorial study with diets of 20% or 40% fat and 15% or 25% protein with a graded carbohydrate intake of 35, 45, 55 and 65%. Weight loss, overall, was modest at nearly 6% with all four diets, and no significant dietary difference. The variability in weight loss in each diet group was significant, ranging from greater than 20% to a small weight gain. Studies of genetic variations in relation to weight loss showed that the diet that was selected could significantly affect weight loss, emphasizing that there is no ideal diet and more than one diet can be used to treat obesity. Weight loss was also influenced by the level of baseline triiodothyronine or thyroxine, and baseline carbohydrate and insulin resistance. Achieving a stable Health Eating Food Diversity Index, eating more protein, eating more fiber, engaging in more physical activity, sleeping better and eating less ultra-processed foods were beneficial strategies for weight loss in this trial. Although there is no "ideal diet", both the DASH diet and the Mediterranean diet have clinical trials showing their significant benefit for cardiovascular risk factors. Finally, the lesson of the "Last Chance Diet", which recommended a diet with protein from gelatin, proved that some diets could be hazardous.

The effect of observing religious or faith-based fasting on cardiovascular disease risk factors: A systematic review and meta-analysis

AIMS

Cardiovascular diseases (CVD) are the leading cause of death worldwide. Fasting is common in many religions and is associated with health benefits. This systematic review to compares the impact of different religious fasting practices, on risk of cardiometabolic diseases.

DATA SYNTHESIS

The search covered five databases following PRISMA guidelines to identify papers published in English from inception to March 2023 (updated January 2024). Inclusion criteria were healthy adults in observational studies, who engaged in religious fasting practices, studies were included where data on matched non-fasting individuals was available. Outcomes were systolic and diastolic blood pressure, body mass index (BMI), triglycerides, total cholesterol (TC), low-density lipoprotein cholesterol (LDLc), high-density lipoprotein cholesterol (HDLc), and fasting plasma glucose levels. A meta-analysis was conducted, and the review was registered (CRD42022352197). Fourteen studies were met the inclusion criteria with ten studies data being suitable for meta-analysis, reporting on 755 adults participating in fasting practices and 661 non-fasting controls. Religious fasting was associated with a reduction in BMI (-0.40 kg/m2, 95% CI [-0.70, -0.10], p < 0.01). Observance of Ramadan fasting was associated with decreased systolic blood pressure (-3.83  mmHg, 95% CI [-7.44, -0.23], p = 0.04). The observance of Orthodox Christian fasting was associated with a reduction in TC (-0.52 mmoL/l, 95%CI [-0.64, -0.39], p < 0.01). No difference was found for the other outcomes.

CONCLUSION

This review found religious fasting practices which were associated with a reduction in some biomarkers of cardiometabolic diseases risk. Further research on other fasting practices is needed due to limited data.

Precision nutrition for targeting pathophysiology of cardiometabolic phenotypes

Obesity is a heterogenous disease accompanied by a broad spectrum of cardiometabolic risk profiles. Traditional paradigms for dietary weight management do not address biological heterogeneity between individuals and have catastrophically failed to combat the global pandemic of obesity-related diseases. Nutritional strategies that extend beyond basic weight management to instead target patient-specific pathophysiology are warranted. In this narrative review, we provide an overview of the tissue-level pathophysiological processes that drive patient heterogeneity to shape distinct cardiometabolic phenotypes in obesity. Specifically, we discuss how divergent physiology and postprandial phenotypes can reveal key metabolic defects within adipose, liver, or skeletal muscle, as well as the integrative involvement of the gut microbiome and the innate immune system. Finally, we highlight potential precision nutritional approaches to target these pathways and discuss recent translational evidence concerning the efficacy of such tailored dietary interventions for different obesity phenotypes, to optimise cardiometabolic benefits.

Predicting weight loss success on a new Nordic diet: an untargeted multi-platform metabolomics and machine learning approach

Background and aim

Results from randomized controlled trials indicate that no single diet performs better than other for all people living with obesity. Regardless of the diet plan, there is always large inter-individual variability in weight changes, with some individuals losing weight and some not losing or even gaining weight. This raises the possibility that, for different individuals, the optimal diet for successful weight loss may differ. The current study utilized machine learning to build a predictive model for successful weight loss in subjects with overweight or obesity on a New Nordic Diet (NND).

Methods

Ninety-one subjects consumed an NND ad libitum for 26 weeks. Based on their weight loss, individuals were classified as responders (weight loss ≥5%, n = 46) or non-responders (weight loss <2%, n = 24). We used clinical baseline data combined with baseline urine and plasma untargeted metabolomics data from two different analytical platforms, resulting in a data set including 2,766 features, and employed symbolic regression (QLattice) to develop a predictive model for weight loss success.

Results

There were no differences in clinical parameters at baseline between responders and non-responders, except age (47 ± 13 vs. 39 ± 11 years, respectively, p = 0.009). The final predictive model for weight loss contained adipic acid and argininic acid from urine (both metabolites were found at lower levels in responders) and generalized from the training (AUC 0.88) to the test set (AUC 0.81). Responders were also able to maintain a weight loss of 4.3% in a 12 month follow-up period.

Conclusion

We identified a model containing two metabolites that were able to predict the likelihood of achieving a clinically significant weight loss on an ad libitum NND. This work demonstrates that models based on an untargeted multi-platform metabolomics approach can be used to optimize precision dietary treatment for obesity.

The role of cereal soluble fiber in the beneficial modulation of glycometabolic gastrointestinal hormones

According to cohort studies, cereal fiber, and whole-grain products might decrease risk for type 2 diabetes (T2DM), inflammatory processes, cancer, and cardiovascular diseases. These associations, mainly affect insoluble, but not soluble cereal fiber. In intervention studies, soluble fiber elicit anti-hyperglycemic and anti-inflammatory short-term effects, partially explained by fermentation to short-chain fatty acids, which acutely counteract insulin resistance and inflammation. ß-glucans lower cholesterol levels and possibly reduce liver fat. Long-term benefits are not yet shown, maybe caused by T2DM heterogeneity, as insulin resistance and fatty liver disease - the glycometabolic points of action of soluble cereal fiber - are not present in every patient. Thus, only some patients might be susceptive to fiber. Also, incretin action in response to fiber could be a relevant factor for variable effects. Thus, this review aims to summarize the current knowledge from human studies on the impact of soluble cereal fiber on glycometabolic gastrointestinal hormones. Effects on GLP-1 appear to be highly contradictory, while these fibers might lower GIP and ghrelin, and increase PYY and CCK. Even though previous results of specific trials support a glycometabolic benefit of soluble fiber, larger acute, and long-term mechanistic studies are needed in order to corroborate the results.

Predicting Factors for Metabolic Non-Response to a Complex Lifestyle Intervention-A Replication Analysis to a Randomized-Controlled Trial

BACKGROUND

T2DM heterogeneity affects responsiveness to lifestyle treatment. Beta-cell failure and nonalcoholic fatty liver disease (NAFLD) independently predict T2DM, but NAFLD inconsistently predicts metabolic response to lifestyle intervention.

AIM

We attempt to replicate a prediction model deducted from the Tübinger Lifestyle Intervention Program by assessing similar metabolic factors to predict conversion to normal glucose regulation (NGR) in a comparable lifestyle intervention trial.

METHODS

In the Optimal Fiber Trial (OptiFiT), 131 Caucasian participants with prediabetes completed a one-year lifestyle intervention program and received a fiber or placebo supplement. We compared baseline parameters for responders and non-responders, assessed correlations of major metabolic changes and conducted a logistic regression analysis for predictors of remission to NGR.

RESULTS

NGR was achieved by 33 participants, respectively. At baseline, for the placebo group only, 1 h and 2 h glucose levels, glucose AUC and Cederholm index predicted conversion to NGR. HOMA-beta, HOMA-IR or liver fat indices did not differ between responders and non-responders of the placebo or the fiber group. Changes in waist circumference or fatty liver index correlated with changes in glycemia and insulin resistance, but not with changes in insulin secretion. Insulin-resistant NAFLD did not predict non-response. Differences in compliance did not explain the results.

CONCLUSIONS

Higher post-challenge glucose levels strongly predicted the metabolic non-response to complex lifestyle intervention in our cohort. Depending on the specific intervention and the investigated cohort, fasting glucose levels and insulin sensitivity might contribute to the risk pattern. Beta-cell function did not improve in accordance with other metabolic improvements, qualifying as a potential risk factor for non-response. We could not replicate previous data suggesting that an insulin-resistant fatty liver is a specific risk factor for treatment failure. Replication studies are required.

A double-blinded, randomized, parallel intervention to evaluate biomarker-based nutrition plans for weight loss: The PREVENTOMICS study

BACKGROUND & AIMS

Growing evidence suggests that biomarker-guided dietary interventions can optimize response to treatment. In this study, we evaluated the efficacy of the PREVENTOMCIS platform-which uses metabolomic and genetic information to classify individuals into different 'metabolic clusters' and create personalized dietary plans-for improving health outcomes in subjects with overweight or obesity.

METHODS

A 10-week parallel, double-blinded, randomized intervention was conducted in 100 adults (82 completers) aged 18-65 years, with body mass index ≥27 but <40 kg/m², who were allocated into either a personalized diet group (n = 49) or a control diet group (n = 51). About 60% of all food was provided free-of-charge. No specific instruction to restrict energy intake was given. The primary outcome was change in fat mass from baseline, evaluated by dual energy X-ray absorptiometry. Other endpoints included body weight, waist circumference, lipid profile, glucose homeostasis markers, inflammatory markers, blood pressure, physical activity, stress and eating behavior.

RESULTS

There were significant main effects of time (P < 0.01), but no group main effects, or time-by-group interactions, for the change in fat mass (personalized: -2.1 [95% CI -2.9, -1.4] kg; control: -2.0 [95% CI -2.7, -1.3] kg) and body weight (personalized: -3.1 [95% CI -4.1, -2.1] kg; control: -3.3 [95% CI -4.2, -2.4] kg). The difference between groups in fat mass change was -0.1 kg (95% CI -1.2, 0.9 kg, P = 0.77). Both diets resulted in significant improvements in insulin resistance and lipid profile, but there were no significant differences between groups.

CONCLUSION

Personalized dietary plans did not result in greater benefits over a generic, but generally healthy diet, in this 10-week clinical trial. Further studies are required to establish the soundness of different precision nutrition approaches, and translate this science into clinically relevant dietary advice to reduce the burden of obesity and its comorbidities.

CLINICAL TRIAL REGISTRY

ClinicalTrials.gov registry (NCT04590989).

The energy balance model of obesity: beyond calories in, calories out

A recent Perspective article described the "carbohydrate-insulin model (CIM)" of obesity, asserting that it "better reflects knowledge on the biology of weight control" as compared with what was described as the "dominant energy balance model (EBM)," which fails to consider "biological mechanisms that promote weight gain." Unfortunately, the Perspective conflated and confused the principle of energy balance, a law of physics that is agnostic as to obesity mechanisms, with the EBM as a theoretical model of obesity that is firmly based on biology. In doing so, the authors presented a false choice between the CIM and a caricature of the EBM that does not reflect modern obesity science. Here, we present a more accurate description of the EBM where the brain is the primary organ responsible for body weight regulation operating mainly below our conscious awareness via complex endocrine, metabolic, and nervous system signals to control food intake in response to the body's dynamic energy needs as well as environmental influences. We also describe the recent history of the CIM and show how the latest "most comprehensive formulation" abandons a formerly central feature that required fat accumulation in adipose tissue to be the primary driver of positive energy balance. As such, the new CIM can be considered a special case of the more comprehensive EBM but with a narrower focus on diets high in glycemic load as the primary factor responsible for common obesity. We review data from a wide variety of studies that address the validity of each model and demonstrate that the EBM is a more robust theory of obesity than the CIM.

The energy balance model of obesity: beyond calories in, calories out

A recent Perspective article described the "carbohydrate-insulin model (CIM)" of obesity, asserting that it "better reflects knowledge on the biology of weight control" as compared with what was described as the "dominant energy balance model (EBM)," which fails to consider "biological mechanisms that promote weight gain." Unfortunately, the Perspective conflated and confused the principle of energy balance, a law of physics that is agnostic as to obesity mechanisms, with the EBM as a theoretical model of obesity that is firmly based on biology. In doing so, the authors presented a false choice between the CIM and a caricature of the EBM that does not reflect modern obesity science. Here, we present a more accurate description of the EBM where the brain is the primary organ responsible for body weight regulation operating mainly below our conscious awareness via complex endocrine, metabolic, and nervous system signals to control food intake in response to the body's dynamic energy needs as well as environmental influences. We also describe the recent history of the CIM and show how the latest "most comprehensive formulation" abandons a formerly central feature that required fat accumulation in adipose tissue to be the primary driver of positive energy balance. As such, the new CIM can be considered a special case of the more comprehensive EBM but with a narrower focus on diets high in glycemic load as the primary factor responsible for common obesity. We review data from a wide variety of studies that address the validity of each model and demonstrate that the EBM is a more robust theory of obesity than the CIM.

Personal diet-microbiota interactions and weight loss

The aim of this review is to provide an overview of how person-specific interactions between diet and the gut microbiota could play a role in affecting diet-induced weight loss responses. The highly person-specific gut microbiota, which is shaped by our diet, secretes digestive enzymes and molecules that affect digestion in the colon. Therefore, weight loss responses could in part depend on personal colonic fermentation responses, which affect energy extraction of food and production of microbial metabolites, such as short-chain fatty acids (SCFAs), which exert various effects on host metabolism. Colonic fermentation is the net result of the complex interplay between availability of dietary substrates, the functional capacity of the gut microbiome and environmental (abiotic) factors in the gut such as pH and transit time. While animal studies have demonstrated that the gut microbiota can causally affect obesity, causal and mechanistic evidence from human studies is still largely lacking. However, recent human studies have proposed that the baseline gut microbiota composition may predict diet-induced weight loss-responses. In particular, individuals characterised by high relative abundance of Prevotella have been found to lose more weight on diets rich in dietary fibre compared to individuals with low Prevotella abundance. Although harnessing of personal diet-microbiota interactions holds promise for more personalised nutrition and obesity management strategies to improve human health, there is currently insufficient evidence to unequivocally link the gut microbiota and weight loss in human subjects. To move the field forward, a greater understanding of the mechanistic underpinnings of personal diet-microbiota interactions is needed.

Diverging metabolic effects of 2 energy-restricted diets differing in nutrient quality: a 12-week randomized controlled trial in subjects with abdominal obesity

BACKGROUND

Despite the established relation between energy restriction (ER) and metabolic health, the most beneficial nutrient composition of a weight-loss diet is still a subject of debate.

OBJECTIVES

The aim of the study was to examine the additional effects of nutrient quality on top of ER.

METHODS

A parallel-designed, 12-week 25% ER dietary intervention study was conducted (clinicaltrials.gov: NCT02194504). Participants aged 40-70 years with abdominal obesity were randomized over 3 groups: a 25% ER high-nutrient-quality diet (n = 40); a 25% ER low-nutrient-quality diet (n = 40); or a habitual diet (n = 30). Both ER diets were nutritionally adequate, and the high-nutrient-quality ER diet was enriched in MUFAs, n-3 PUFAs, fiber, and plant protein and reduced in fructose. Before and after the intervention, intrahepatic lipids, body fat distribution, fasting and postprandial responses to a mixed-meal shake challenge test of cardiometabolic risk factors, lipoproteins, vascular measurements, and adipose tissue transcriptome were assessed.

RESULTS

The high-nutrient-quality ER diet (-8.4 ± 3.2) induced 2.1 kg more weight loss (P = 0.007) than the low-nutrient-quality ER diet (-6.3 ± 3.9), reduced fasting serum total cholesterol (P = 0.014) and plasma triglycerides (P < 0.001), promoted an antiatherogenic lipoprotein profile, and induced a more pronounced decrease in adipose tissue gene expression of energy metabolism pathways than the low-quality ER diet. Explorative analyses showed that the difference in weight loss between the two ER diets was specifically present in insulin-sensitive subjects (HOMA-IR ≤ 2.5), in whom the high-nutrient-quality diet induced 3.9 kg more weight loss than the low-nutrient-quality diet.

CONCLUSIONS

A high-nutrient-quality 25% ER diet is more beneficial for cardiometabolic health than a low-nutrient-quality 25% ER diet. Overweight, insulin-sensitive subjects may benefit more from a high- than a low-nutrient-quality ER diet with respect to weight loss, due to potential attenuation of glucose-induced lipid synthesis in adipose tissue.

The carbohydrate-insulin model: a physiological perspective on the obesity pandemic

According to a commonly held view, the obesity pandemic is caused by overconsumption of modern, highly palatable, energy-dense processed foods, exacerbated by a sedentary lifestyle. However, obesity rates remain at historic highs, despite a persistent focus on eating less and moving more, as guided by the energy balance model (EBM). This public health failure may arise from a fundamental limitation of the EBM itself. Conceptualizing obesity as a disorder of energy balance restates a principle of physics without considering the biological mechanisms that promote weight gain. An alternative paradigm, the carbohydrate-insulin model (CIM), proposes a reversal of causal direction. According to the CIM, increasing fat deposition in the body-resulting from the hormonal responses to a high-glycemic-load diet-drives positive energy balance. The CIM provides a conceptual framework with testable hypotheses for how various modifiable factors influence energy balance and fat storage. Rigorous research is needed to compare the validity of these 2 models, which have substantially different implications for obesity management, and to generate new models that best encompass the evidence.

Alternative Dietary Patterns for Americans: Low-Carbohydrate Diets

The decades-long dietary experiment embodied in the Dietary Guidelines for Americans (DGA) focused on limiting fat, especially saturated fat, and higher carbohydrate intake has coincided with rapidly escalating epidemics of obesity and type 2 diabetes (T2D) that are contributing to the progression of cardiovascular disease (CVD) and other diet-related chronic diseases. Moreover, the lack of flexibility in the DGA as it pertains to low carbohydrate approaches does not align with the contemporary trend toward precision nutrition. We argue that personalizing the level of dietary carbohydrate should be a high priority based on evidence that Americans have a wide spectrum of metabolic variability in their tolerance to high carbohydrate loads. Obesity, metabolic syndrome, and T2D are conditions strongly associated with insulin resistance, a condition exacerbated by increased dietary carbohydrate and improved by restricting carbohydrate. Low-carbohydrate diets are grounded across the time-span of human evolution, have well-established biochemical principles, and are now supported by multiple clinical trials in humans that demonstrate consistent improvements in multiple established risk factors associated with insulin resistance and cardiovascular disease. The American Diabetes Association (ADA) recently recognized a low carbohydrate eating pattern as an effective approach for patients with diabetes. Despite this evidence base, low-carbohydrate diets are not reflected in the DGA. As the DGA Dietary Patterns have not been demonstrated to be universally effective in addressing the needs of many Americans and recognizing the lack of widely available treatments for obesity, metabolic syndrome, and T2D that are safe, effective, and sustainable, the argument for an alternative, low-carbohydrate Dietary Pattern is all the more compelling.

Diet Composition, Glucose Homeostasis, and Weight Regain in the YoYo Study

Based on several randomized clinical trials, it has been suggested that baseline glucose homeostasis interacts with the influence of diet composition on weight loss and weight loss maintenance. In this secondary analysis of the YoYo study, a study investigating predictors of weight loss maintenance, we tested the hypothesis that (self-selected) dietary carbohydrate and/or fibre intake interact with the glucose homeostasis parameters for weight loss maintenance. Sixty-one overweight or obese individuals lost around 10 kg of body weight on an energy-restricted diet and were then followed for 9 months. During this period, participants were advised to maintain their body weight and eat a healthy diet without further recommendations on calorie intake or diet composition. Contrary to our hypothesis, carbohydrate intake showed no positive association with weight regain after weight loss, and no interaction with baseline fasting glucose concentration was found. There was a non-significant negative association between fibre intake and weight regain (B = −0.274, standard error (SE) 0.158, p = 0.090), but again, no interaction with fasting plasma glucose was found. In conclusion, the data from the YoYo study do not support a role for baseline glucose homeostasis in determining the association between self-reported carbohydrate and/or fibre intake and weight regain after weight loss.

High-Protein, Low-Glycaemic Meal Replacement Decreases Fasting Insulin and Inflammation Markers-A 12-Month Subanalysis of the ACOORH Trial

Lifestyle interventions, including meal replacement, are effective in the prevention and treatment of type-2-diabetes and obesity. Since insulin is the key weight regulator, we hypothesised that the addition of meal replacement to a lifestyle intervention reduces insulin levels more effectively than lifestyle intervention alone. In the international multicentre randomised controlled ACOORH (Almased Concept against Overweight and Obesity and Related Health Risk) trial, overweight or obese persons who meet the criteria for metabolic syndrome (n = 463) were randomised into two groups. Both groups received nutritional advice focusing on carbohydrate restriction and the use of telemonitoring devices. The intervention group substituted all three main meals per day in week 1, two meals per day in weeks 2–4, and one meal per day in weeks 5–26 with a protein-rich, low-glycaemic meal replacement. Data were collected at baseline and after 1, 3, 6 and 12 months. All datasets providing insulin data (n = 446) were included in this predefined subanalysis. Significantly higher reductions in insulin (−3.3 ± 8.7 µU/mL vs. −1.6 ± 9.8 µU/mL), weight (−6.1 ± 5.2 kg vs. −3.2 ± 4.6 kg), and inflammation markers were observed in the intervention group. Insulin reduction correlated with weight reduction and the highest amount of weight loss (−7.6 ± 4.9 kg) was observed in those participants with an insulin decrease > 2 µU/mL. These results underline the potential for meal replacement-based lifestyle interventions in diabetes prevention, and measurement of insulin levels may serve as an indicator for adherence to carbohydrate restriction.

Stool metabolome-microbiota evaluation among children and adolescents with obesity, overweight, and normal-weight using 1H NMR and 16S rRNA gene profiling

Characterization of metabolites and microbiota composition from human stool provides powerful insight into the molecular phenotypic difference between subjects with normal weight and those with overweight/obesity. The aim of this study was to identify potential metabolic and bacterial signatures from stool that distinguish the overweight/obesity state in children/adolescents. Using ¹H NMR spectral analysis and 16S rRNA gene profiling, the fecal metabolic profile and bacterial composition from 52 children aged 7 to 16 was evaluated. The children were classified into three groups (16 with normal-weight, 17 with overweight, 19 with obesity). The metabolomic analysis identified four metabolites that were significantly different (p < 0.05) among the study groups based on one-way ANOVA testing: arabinose, butyrate, galactose, and trimethylamine. Significantly different (p < 0.01) genus-level taxa based on edgeR differential abundance tests were genus Escherichia and Tyzzerella subgroup 3. No significant difference in alpha-diversity was detected among the three study groups, and no significant correlations were found between the significant taxa and metabolites. The findings support the hypothesis of increased energy harvest in obesity by human gut bacteria through the growing observation of increased fecal butyrate in children with overweight/obesity, as well as an increase of certain monosaccharides in the stool. Also supported is the increase of trimethylamine as an indicator of an unhealthy state.

[Lipids should not be demonized in adults and in infants]

Following a long and dogmatic period, which has demonized the dietary lipids, a cautious review of the literature led the scientists to propose a new paradigm and rehabilitation for lipids. French guidelines have endorsed it since 2010, and recent data confirm this new and necessary approach, especially for infants.

Randomized Controlled Lifestyle Intervention (LION) Study for Weight Loss and Maintenance in Adults With Obesity-Design and Methods

Introduction: Due to the increasing prevalence of obesity, approaches for a more effective treatment especially in the long-term perspective are needed. However, studies on weight loss and maintenance show heterogeneous results with large inter-individual variations. Therefore, it is of interest to identify factors that contribute to inter-individual differences and predict the success of long-term weight management.

Methods and Analysis: The primary outcome of the Lifestyle Intervention (LION) Study is to evaluate the effect of two diets (low carb vs. low fat) and two digital counseling tools (newsletter vs. mobile application) on weight maintenance 12 months after weight loss. The identification of predictive factors (e.g., genetic, epigenetic, physiological, psychological) for the success of weight loss and maintenance is a secondary outcome. Men and women with a body mass index (BMI) between 30.0 and 39.9 kg/m², aged 18–65 years, and without severe diseases are considered eligible. After phenotyping (e.g., anthropometry, resting metabolic rate, meal challenges, blood parameters) participants will follow a formula-based, low-calorie diet (LCD) for 8 weeks. In addition, the intake of 200 g raw or cooked non-starchy vegetables are allowed per day. Subsequently, 252 participants will be randomized into one of the four intervention groups (low carb/app, low carb/newsletter, low fat/app, low fat/newsletter) for the 12-month weight maintenance step. The study will be concluded after another 12 months of follow-up. Results should provide indications for successful weight management and give insights into the personalized treatment of obesity.

Ethics and Dissemination: This study has been granted ethical approval by the local Ethics Review Committee of the School of Medicine, Technical University of Munich (vote: 69/19 S).

Trial Registration Number: This study has been registered within ClinicalTrials.gov (NCT04023942) and the German Clinical Trials Register (DRKS00017819).

Data integration for prediction of weight loss in randomized controlled dietary trials

Diet is an important component in weight management strategies, but heterogeneous responses to the same diet make it difficult to foresee individual weight-loss outcomes. Omics-based technologies now allow for analysis of multiple factors for weight loss prediction at the individual level. Here, we classify weight loss responders (N = 106) and non-responders (N = 97) of overweight non-diabetic middle-aged Danes to two earlier reported dietary trials over 8 weeks. Random forest models integrated gut microbiome, host genetics, urine metabolome, measures of physiology and anthropometrics measured prior to any dietary intervention to identify individual predisposing features of weight loss in combination with diet. The most predictive models for weight loss included features of diet, gut bacterial species and urine metabolites (ROC-AUC: 0.84-0.88) compared to a diet-only model (ROC-AUC: 0.62). A model ensemble integrating multi-omics identified 64% of the non-responders with 80% confidence. Such models will be useful to assist in selecting appropriate weight management strategies, as individual predisposition to diet response varies.

Associations of the serum metabolite profile with a healthy Nordic diet and risk of coronary artery disease

BACKGROUND & AIM

A healthy Nordic diet (HND) rich in wholegrain cereals, berries, vegetables, and fish, has been associated with a lower risk of cardiovascular disease, but the molecular links remain unclear. Here, we present the application of nontargeted metabolic profiling based on liquid chromatography with tandem mass spectrometry (LC-MS/MS) to identify metabolites that would potentially reflect the adherence to HND and their relationship with the risk of coronary artery disease (CAD).

METHODS

From a Finnish population-based prospective cohort (Kuopio Ischaemic Heart Disease Risk Factor Study; KIHD), we collected 364 baseline serum samples in 4 groups: 1) 94 participants with high adherence to HND who developed CAD during the follow-up of 20.4 ± 7.6 years (cases), 2) 88 participants with high adherence who did not develop CAD during follow-up (controls), 3) 93 CAD cases with low adherence, and 4) 89 controls with low adherence.

RESULTS

Indolepropionic acid, proline betaine, vitamin E derivatives, and medium-chain acylcarnitines were associated with adherence to HND after adjustments for age, waist-to-hip ratio (WHR), physical activity, and total cholesterol. These metabolites also correlated negatively with blood lipid profiles, BMI, insulin, inflammation marker high-sensitivity C reactive protein (hsCRP), smoking, and alcohol consumption, as well as positively with physical activity. Predictors of CAD risk included several lipid molecules, which also indicated lower adherence to HND. But, only the associations with the plasmalogens PC(O-16:0/18:2) and PC(O-16:1/18:2) remained significant after adjusting for age, smoking, systolic blood pressure, LDL cholesterol, and WHR. These plasmalogens did not correlate with any investigated risk factors of CAD at baseline, which may highlight their potential as novel predictors of CAD risk. Interestingly, the metabolic profile predicting CAD risk differed based on the adherence to HND. Also, HND adherence was more distinct within CAD cases than controls, which may emphasize the interaction between HND adherence and CAD risk.

CONCLUSIONS

The association between higher adherence to HND and a lower risk of CAD likely involves a complex interaction of various endogenous, plant-, and microbial-derived metabolites.

Microbial enterotypes beyond genus level: Bacteroides species as a predictive biomarker for weight change upon controlled intervention with arabinoxylan oligosaccharides in overweight subjects

Recent studies indicate that microbial enterotypes may influence the beneficial effects of wholegrain enriched diets including bodyweight regulation. In a 4-week intervention trial, overweight subjects were randomized to consume either arabinoxylan-oligosaccharides (AXOS) (10.4 g/d) from wheat bran or polyunsaturated fatty acids (PUFA) (3.6 g/d). In the present study, we have stratified the subjects participating in the intervention (n = 29) according to the baseline Prevotella-to-Bacteroides (P/B) ratios through a post-hoc analysis and applied a linear mixed model analysis to identify the influence of this P/B ratio on the differences in weight changes in the intervention arms. Following AXOS consumption (n = 15), the high P/B group showed no bodyweight changes [-0.14 kg (95% CI: -0.67; 0.38, p = .59)], while the low P/B group gained 0.65 kg (95% CI: 0.16; 1.14, p = .009). Consequently, a difference of -0.79 kg was found between P/B groups (95% CI: -1.51; -0.08, p = .030). No differences were found between P/B groups following PUFA consumption (0.61 kg, 95% CI: -0.13; 1.35, p = .10). Among the Bacteroides species, B. cellulosilyticus relative abundance exhibited the highest positive rank correlation (Kendall's tau = 0.51, FDR p = .070) with 4-week weight change on AXOS, and such association was further supported by using supervised classification methods (Random Forest). We outlined several carbohydrate-active enzyme (CAZy) genes involved in xylan-binding and degradation to be enriched in B. cellulosilyticus genomes, as well as multiple accessory genes, suggesting a supreme AXOS-derived glycan scavenging role of such species. This post-hoc analysis, ensuring species and strain demarcation at the human gut microbiota, permitted to uncover the predictive role of Bacteroides species over P/B enterotype in weight gain during a fiber-based intervention. The results of this pilot trial pave the way for future assessments on fiber fermentation outputs from Bacteroides species affecting lipid metabolism in the host and with direct impact on adiposity, thus helping to design personalized interventions.

Diet and exercise in the prevention and treatment of type 2 diabetes mellitus

Evidence from observational studies and randomized trials suggests that prediabetes and type 2 diabetes mellitus (T2DM) can develop in genetically susceptible individuals in parallel with weight (that is, fat) gain. Accordingly, studies show that weight loss can produce remission of T2DM in a dose-dependent manner. A weight loss of ~15 kg, achieved by calorie restriction as part of an intensive management programme, can lead to remission of T2DM in ~80% of patients with obesity and T2DM. However, long-term weight loss maintenance is challenging. Obesity and T2DM are associated with diminished glucose uptake in the brain that impairs the satiating effect of dietary carbohydrate; therefore, carbohydrate restriction might help maintain weight loss and maximize metabolic benefits. Likewise, increases in physical activity and fitness are an important contributor to T2DM remission when combined with calorie restriction and weight loss. Preliminary studies suggest that a precision dietary management approach that uses pretreatment glycaemic status to stratify patients can help optimize dietary recommendations with respect to carbohydrate, fat and dietary fibre. This approach might lead to improved weight loss maintenance and glycaemic control. Future research should focus on better understanding the individual response to dietary treatment and translating these findings into clinical practice.

Changes in biochemical parameters by gender and time: Effect of short-term vegan diet adherence

Background

Vegetarian diets adapted for various reasons that may include religious, ethical, and health considerations have reasonable health benefits including weight loss, and favorable metabolic changes. However, studies that assessed health benefits associated with vegan diet practices during the Ethiopian Orthodox Christian (EOC) Lenten fasting remains limited. This study has, therefore, assessed how short-term vegan diet associated with metabolic traits, including weight, body mass index (BMI), circumference, blood pressure, total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), through longitudinal cross-sectional study design.

Methods

Seventy-five subjects (34 females and 41 males) with a mean age of [+SD] 27.3 + 5.8 years (range, 18 and 35) took part in the study. The study followed three assessment sessions: at baseline, during the Lenten (week 7), and 7 weeks after the end of the Lenten (week 14). An automatic chemistry analyzer (Mindray, BE-2000, China) used for lipid profile analysis. We used paired sample t-test in pre and post-performance and repeated measures ANOVA with Bonferroni post hoc adjustment between time points. The statistical significance was set at p < 0.05.

Results

The EOC fasting with vegan diet induced significantly lower blood pressure, weight, BMI, TC, HDL-C, LDL-C, and TC: HDL-C ratios, during Lenten (that is vegan diet consumption), but a regain noted in these parameters 7-weeks after Lenten (that is omnivore diet). On gender differences, vegan diet associated with significantly lower blood pressure, TC, and LDL-C in females compared with age-matched male counterparts. Some methodological limitations of this study are discussed with particular reference to lack of a randomized control group and self-reported data that limit this study in establishing a causal relationship through observed associations.

Conclusions

Vegan diet consumption even for short period corroborate ideal metabolic traits, with more favorable changes noted in women than age-matched men counterparts. These findings might help to define vegetarian diets as part of religious fasting (beyond its spiritual goals) as a non-pharmacological prescription in different populations, and our findings add to growing evidence in these subjects.

Energy Requirement Is Higher During Weight-Loss Maintenance in Adults Consuming a Low- Compared with High-Carbohydrate Diet

BACKGROUND

Longer-term feeding studies suggest that a low-carbohydrate diet increases energy expenditure, consistent with the carbohydrate-insulin model of obesity. However, the validity of methodology utilized in these studies, involving doubly labeled water (DLW), has been questioned.

OBJECTIVE

The aim of this study was to determine whether dietary energy requirement for weight-loss maintenance is higher on a low- compared with high-carbohydrate diet.

METHODS

The study reports secondary outcomes from a feeding study in which the primary outcome was total energy expenditure (TEE). After attaining a mean Run-in weight loss of 10.5%, 164 adults (BMI ≥25 kg/m2; 70.1% women) were randomly assigned to Low-Carbohydrate (percentage of total energy from carbohydrate, fat, protein: 20/60/20), Moderate-Carbohydrate (40/40/20), or High-Carbohydrate (60/20/20) Test diets for 20 wk. Calorie content was adjusted to maintain individual body weight within ± 2 kg of the postweight-loss value. In analyses by intention-to-treat (ITT, completers, n = 148) and per protocol (PP, completers also achieving weight-loss maintenance, n = 110), we compared the estimated energy requirement (EER) from 10 to 20 wk of the Test diets using ANCOVA.

RESULTS

Mean EER was higher in the Low- versus High-Carbohydrate group in models of varying covariate structure involving ITT [ranging from 181 (95% CI: 8-353) to 246 (64-427) kcal/d; P ≤0.04] and PP [ranging from 245 (43-446) to 323 (122-525) kcal/d; P ≤0.02]. This difference remained significant in sensitivity analyses accounting for change in adiposity and possible nonadherence.

CONCLUSIONS

Energy requirement was higher on a low- versus high-carbohydrate diet during weight-loss maintenance in adults, commensurate with TEE. These data are consistent with the carbohydrate-insulin model and lend qualified support for the validity of the DLW method with diets varying in macronutrient composition. This trial was registered at clinicaltrials.gov as NCT02068885.

Saturated Fats and Health: A Reassessment and Proposal for Food-Based Recommendations: JACC State-of-the-Art Review

The recommendation to limit dietary saturated fatty acid (SFA) intake has persisted despite mounting evidence to the contrary. Most recent meta-analyses of randomized trials and observational studies found no beneficial effects of reducing SFA intake on cardiovascular disease (CVD) and total mortality, and instead found protective effects against stroke. Although SFAs increase low-density lipoprotein (LDL) cholesterol, in most individuals, this is not due to increasing levels of small, dense LDL particles, but rather larger LDL particles, which are much less strongly related to CVD risk. It is also apparent that the health effects of foods cannot be predicted by their content in any nutrient group without considering the overall macronutrient distribution. Whole-fat dairy, unprocessed meat, and dark chocolate are SFA-rich foods with a complex matrix that are not associated with increased risk of CVD. The totality of available evidence does not support further limiting the intake of such foods.

Association of Dietary Patterns and Type-2 Diabetes Mellitus in Metabolically Homogeneous Subgroups in the KORA FF4 Study

There is evidence that a change in lifestyle, especially physical activity and diet, can reduce the risk of developing type-2 diabetes mellitus (T2DM). However, the response to dietary changes varies among individuals due to differences in metabolic characteristics. Therefore, we investigated the association between dietary patterns and T2DM while taking into account these differences. For 1287 participants of the population-based KORA FF4 study (Cooperative Health Research in the Region of Augsburg), we identified three metabolically-homogenous subgroups (metabotypes) using 16 clinical markers. Based on usual dietary intake data, two diet quality scores, the Mediterranean Diet Score (MDS) and the Alternate Healthy Eating Index (AHEI), were calculated. We explored the associations between T2DM and diet quality scores. Multi-variable adjusted models, including metabotype subgroup, were fitted. In addition, analyses stratified by metabotype were carried out. We found significant interaction effects between metabotype and both diet quality scores (p < 0.05). In the analysis stratified by metabotype, significant negative associations between T2DM and both diet quality scores were detected only in the metabolically-unfavorable homogenous subgroup (Odds Ratio (OR) = 0.62, 95% confidence interval (CI) = 0.39-0.90 for AHEI and OR = 0.60, 95% CI = 0.40-0.96 for MDS). Prospective studies taking metabotype into account are needed to confirm our results, which allow for the tailoring of dietary recommendations in the prevention of T2DM.

Potential Cardiometabolic Health Benefits of Full-Fat Dairy: The Evidence Base

Since their inception in 1980, the Dietary Guidelines for Americans have promoted low- or fat-free dairy foods. Removing fat from dairy does not reduce putatively beneficial nutrients per serving, including calcium, vitamin D, and potassium. Additionally, links between saturated fat and dietary cholesterol intakes with cardiovascular disease risk have helped to sustain the view that low-fat dairy foods should be recommended. Emerging evidence shows that the consumption of full-fat dairy foods has a neutral or inverse association with adverse cardiometabolic health outcomes, including atherosclerotic cardiovascular disease, type 2 diabetes, and associated risk factors. Thus, although low-fat dairy is a practical, practice-based recommendation, its superiority compared with full-fat dairy is not obviously supported by results from recent prospective cohort studies or intervention trials. To evaluate the emerging science on full-fat dairy, a group of nutrition experts convened to summarize and discuss the scientific evidence regarding the health effects of consuming full-fat dairy foods. Future studies should focus on full-fat dairy foods (milk, yogurt, and cheese) in the context of recommended dietary patterns and consider meal composition and metabolic phenotype in assessing the relation between full-fat dairy consumption and cardiometabolic health.

Perspective: Metabotyping-A Potential Personalized Nutrition Strategy for Precision Prevention of Cardiometabolic Disease

Diet is an important, modifiable lifestyle factor of cardiometabolic disease risk, and an improved diet can delay or even prevent the onset of disease. Recent evidence suggests that individuals could benefit from diets adapted to their genotype and phenotype: that is, personalized nutrition. A novel strategy is to tailor diets for groups of individuals according to their metabolic phenotypes (metabotypes). Randomized controlled trials evaluating metabotype-specific responses and nonresponses are urgently needed to bridge the current gap of knowledge with regard to the efficacy of personalized strategies in nutrition. In this Perspective, we discuss the concept of metabotyping, review the current literature on metabotyping in the context of cardiometabolic disease prevention, and suggest potential strategies for metabotype-based nutritional advice for future work. We also discuss potential determinants of metabotypes, including gut microbiota, and highlight the use of metabolomics to define effective markers for cardiometabolic disease-related metabotypes. Moreover, we hypothesize that people at high risk for cardiometabolic diseases have distinct metabotypes and that individuals grouped into specific metabotypes may respond differently to the same diet, which is being tested in a project of the Joint Programming Initiative: A Healthy Diet for a Healthy Life.

Pretreatment Prevotella-to-Bacteroides ratio and salivary amylase gene copy number as prognostic markers for dietary weight loss

BACKGROUND

The inconsistent link observed between salivary amylase gene copy number (AMY1 CN) and weight management is likely modified by diet and microbiome.

OBJECTIVE

Based on analysis of a previously published study, we investigated the hypothesis that interaction between diet, Prevotella-to-Bacteriodes ratio (P/B ratio), and AMY1 CN influence weight change.

METHODS

Sixty-two people with increased waist circumference were randomly assigned to receive an ad libitum New Nordic Diet (NND) high in dietary fiber, whole grain, intrinsic sugars, and starch or an Average Danish (Western) Diet (ADD) for 26 weeks. All foods were provided free of charge. Before subjects were randomly assigned to receive the NND or ADD diet, blood and fecal samples were collected, from which AMY1 CN and P/B ratio, respectively, were determined. Body weight change was described by using linear mixed models, including biomarker [log10(P/B ratio) and/or AMY1 CN] diet-group interactions.

RESULTS

Baseline means ± SDs of log10(P/B ratio) and AMY1 CN were -2.1 ± 1.8 and 6.6 ± 2.4, respectively. Baseline P/B ratio predicted a 0.99-kg/unit (95% CI: 0.40, 1.57; n = 54; P < 0.001) higher weight loss for those subjects on the NND compared with those on the ADD diet, whereas AMY1 CN was not found to predict weight loss differences between the NND and ADD groups [0.05 kg/CN (95% CI: -0.40, 0.51; n = 54; P = 0.83)]. However, among subjects with low AMY1 CN (<6.5 copies), baseline P/B ratio predicted a 2.12-kg/unit (95% CI: 1.37, 2.88; n = 30; P < 0.001) higher weight loss for the NND group than the ADD group. No such differences in weight loss were found among subjects in both groups with high AMY1 CN [-0.17 kg/unit (95% CI: -1.01, 0.66; n = 24; P = 0.68)].

CONCLUSIONS

The combined use of low AMY1 CN and pretreatment P/B ratio for weight loss prediction led to highly individualized weight loss results with the introduction of more fiber, whole grain, intrinsic sugars, and starch in the diet. These preliminary observations suggest that more undigested starch reaches the colon in individuals with low AMY1 CN, and that the fate of this starch depends on the gut microbiota composition. This trial was registered at clinicaltrials.gov as NCT01195610.

A Perspective on the Transition to Plant-Based Diets: a Diet Change May Attenuate Climate Change, but Can It Also Attenuate Obesity and Chronic Disease Risk?

Current dietary guidelines advocate more plant-based, sustainable diets on the basis of scientific evidence about diet-health relations but also to address environmental concerns. Here, we critically review the effects of plant-based diets on the prevalence of obesity and other health outcomes. Plant-based diets per se have limited efficacy for the prevention and treatment of obesity, but most have beneficial effects in terms of chronic disease risk. However, with the considerable possibilities of translating plant-based diets into various types of dietary patterns, our analysis suggests that potential adverse health effects should also be considered in relation to vulnerable groups of the population. A transition to more plant-based diets may exert beneficial effects on the environment, but is unlikely to affect obesity, and may also have adverse health effects if this change is made without careful consideration of the nutritional needs of the individual relative to the adequacy of the dietary intake.

Biomarkers of a Healthy Nordic Diet-From Dietary Exposure Biomarkers to Microbiota Signatures in the Metabolome

Whole diets and dietary patterns are increasingly highlighted in modern nutrition and health research instead of single food items or nutrients alone. The Healthy Nordic Diet is a dietary pattern typically associated with beneficial health outcomes in observational studies, but results from randomized controlled trials are mixed. Dietary assessment is one of the greatest challenges in observational studies and compliance is a major challenge in dietary interventions. During the last decade, research has shown the great importance of the gut microbiota in health and disease. Studies have have both shown that the Nordic diet affects the gut microbiota and that the gut microbiota predicts the effects of such a diet. Rapid technique developments in the area of high-throughput mass spectrometry have enabled the large-scale use of metabolomics both as an objective measurement of dietary intake as well as in providing the final readout of the endogenous metabolic processes and the impact of the gut microbiota. In this review, we give an update on the current status on biomarkers that reflect a Healthy Nordic Diet or individual components thereof (food intake biomarkers), biomarkers that show the effects of a Healthy Nordic Diet and biomarkers reflecting the role of a Healthy Nordic Diet on the gut microbiota as well as how the gut microbiota or derived molecules may be used to predict the effects of a Healthy Nordic Diet on different outcomes.

Low Carbohydrate and Low-Fat Diets: What We Don't Know and Why we Should Know It

In the 1940s, the diet-heart hypothesis proposed that high dietary saturated fat and cholesterol intake promoted coronary heart disease in "at-risk" individuals. This hypothesis prompted federal recommendations for a low-fat diet for "high risk" patients and as a preventive health measure for everyone except infants. The low carbohydrate diet, first used to treat type 1 diabetes, became a popular obesity therapy with the Atkins diet in the 1970s. Its predicted effectiveness was based largely on the hypothesis that insulin is the causa prima of weight gain and regain via hyperphagia and hypometabolism during and after weight reduction, and therefore reduced carbohydrate intake would promote and sustain weight loss. Based on literature reviews, there are insufficient randomized controlled inpatient studies examining the physiological significance of the mechanisms proposed to support one over the other. Outpatient studies can be confounded by poor diet compliance such that the quality and quantity of the energy intake cannot be ascertained. Many studies also fail to separate macronutrient quantity from quality. Overall, there is no conclusive evidence that the degree of weight loss or the duration of reduced weight maintenance are significantly affected by dietary macronutrient quantity beyond effects attributable to caloric intake. Further work is needed.

Obesity Does Not Modulate the Glycometabolic Benefit of Insoluble Cereal Fibre in Subjects with Prediabetes-A Stratified Post Hoc Analysis of the Optimal Fibre Trial (OptiFiT)

Obesity does not modulate the glycometabolic benefit of insoluble cereal fibre in subjects with prediabetes—a stratified post hoc analysis of the Optimal Fibre Trial (OptiFiT). Background: OptiFiT demonstrated the beneficial effect of insoluble oat fibres on dysglycemia in prediabetes. Recent analyses of OptiFiT and other randomised controlled trials (RCTs) indicated that this effect might be specific for the subgroup of patients with impaired fasting glucose (IFG). As subjects with IFG are more often obese, there is a need to clarify if the effect modulation is actually driven by glycemic state or body mass index (BMI). Aim: We conducted a stratified post hoc analysis of OptiFiT based on the presence or absence of obesity. Methods: 180 Caucasian participants with impaired glucose tolerance (IGT) were randomised in a double-blinded fashion to either twice-a-day fibre or placebo supplementation for 2 years (n = 89 and 91, respectively). Once a year, they underwent fasting blood sampling, an oral glucose tolerance test (oGTT) and full anthropometry. At baseline, out of 136 subjects who completed the first year of intervention, 87 (62%) were classified as OBESE (BMI >30) and 49 subjects were NONOBESE. We performed a stratified per-protocol analysis of the primary glycemic and secondary metabolic effects attributable to dietary fibre supplementation after 1 year of intervention. Results: Neither the NONOBESE nor the OBESE subgroup showed significant differences between the respective fibre and placebo groups in metabolic, anthropometric or inflammatory outcomes. None of the four subgroups showed a significant improvement in either fasting glucose or glycated haemoglobin (HbA1c) after 1 year of intervention and only OBESE fibre subjects improved 2 h glucose. Within the NONOBESE stratum, there were no significant differences in the change of primary or secondary metabolic parameters between the fibre and placebo arms. We found a significant interaction effect for leukocyte count (time × supplement × obesity status). Within the OBESE stratum, leukocyte count and gamma-glutamyl transferase (GGT) levels decreased more in the fibre group compared with placebo (adjusted for change in body weight). Comparison of both fibre groups revealed that OBESE subjects had a significantly stronger benefit with respect to leukocyte count and fasting C-peptide levels than NONOBESE participants. Only the effect on leukocyte count survived correction for multiple comparisons. In contrast, under placebo conditions, NONOBESE subjects managed to decrease their body fat content significantly more than OBESE ones. Intention-to-treat (ITT) analysis resulted in similar outcomes. Conclusions: The state of obesity does not relevantly modulate the beneficial effect of cereal fibre on major glycometabolic parameters by fibre supplementation, but leukocyte levels may be affected. Hence, BMI is not a suitable parameter to stratify this cohort with respect to diabetes risk or responsiveness to cereal fibre, but obesity needs to be accounted for when assessing anti-inflammatory effects of fibre treatments. Targeted diabetes prevention should focus on the actual metabolic state rather than on mere obesity.

The Role of the Gut Microbiome in Predicting Response to Diet and the Development of Precision Nutrition Models. Part II: Results

The gut microbiota is increasingly implicated in the health and metabolism of its human host. The host's diet is a major component influencing the composition and function of the gut microbiota, and mounting evidence suggests that the composition and function of the gut microbiota influence the host's metabolic response to diet. This effect of the gut microbiota on personalized dietary response is a growing focus of precision nutrition research and may inform the effort to tailor dietary advice to the individual. Because the gut microbiota has been shown to be malleable to some extent, it may also allow for therapeutic alterations of the gut microbiota in order to alter response to certain dietary components. This article is the second in a 2-part review of the current research in the field of precision nutrition incorporating the gut microbiota into studies investigating interindividual variability in response to diet. Part I reviews the methods used by researchers to design and carry out such studies as well as analyze the results subsequently obtained. Part II reviews the findings of these studies and discusses the gaps in our current knowledge and directions for future research. The studies reviewed provide the current understanding in this field of research and a foundation from which we may build, utilizing and expanding upon the methods and results they present to inform future studies.

Fasting Glucose State Determines Metabolic Response to Supplementation with Insoluble Cereal Fibre: A Secondary Analysis of the Optimal Fibre Trial (OptiFiT)

Background: High intake of cereal fibre is associated with reduced risk for type 2 diabetes and long-term complications. Within the first long-term randomized controlled trial specifically targeting cereal fibre, the Optimal Fibre Trial (OptiFiT), intake of insoluble oat fibre was shown to significantly reduce glycaemia. Previous studies suggested that this effect might be limited to subjects with impaired fasting glucose (IFG). Aim: We stratified the OptiFiT cohort for normal and impaired fasting glucose (NFG, IFG) and conducted a secondary analysis comparing the effects of fibre supplementation between these subgroups. Methods: 180 Caucasian participants with impaired glucose tolerance (IGT) were randomized to twice-a-day fibre or placebo supplementation for 2 years (n = 89 and 91, respectively), while assuring double-blinded intervention. Fasting blood sampling, oral glucose tolerance test and full anthropometry were assessed annually. At baseline, out of 136 subjects completing the first year of intervention, 72 (54%) showed IFG and IGT, while 64 subjects had IGT only (labelled “NFG”). Based on these two groups, we performed a stratified per-protocol analysis of glycometabolic and secondary effects during the first year of intervention. Results: The NFG group did not show significant differences between fibre and placebo group concerning anthropometric, glycometabolic, or other biochemical parameters. Within the IFG stratum, 2-h glucose, HbA1c, and gamma-glutamyl transferase levels decreased more in the fibre group, with a significant supplement x IFG interaction effect for HbA1c. Compared to NFG subjects, IFG subjects had larger benefits from fibre supplementation with respect to fasting glucose levels. Results were robust against adjustment for weight change and sex. An ITT analysis did not reveal any differences from the per-protocol analysis. Conclusions: Although stratification resulted in relatively small subgroups, we were able to pinpoint our previous findings from the entire cohort to the IFG subgroup. Cereal fibre can beneficially affect glycemic metabolism, with most pronounced or even isolated effectiveness in subjects with impaired fasting glucose.

Pretreatment Prevotella-to-Bacteroides ratio and markers of glucose metabolism as prognostic markers for dietary weight loss maintenance

BACKGROUND/OBJECTIVES

Pre-treatment gut microbial Prevotella-to-Bacteroides (P/B) ratio and markers of glucose metabolism (i.e., fasting glucose and insulin) have been suggested as biomarkers for optimal weight management. However, both biomarkers need further validation, and the interactions between them for optimal weight management are largely unknown. To investigate differences in weight loss maintenance between subjects with low and high P/B ratio and the potential interactions with markers of glucose metabolism and dietary fiber intake.

SUBJECTS/METHODS

Following an 8-week weight loss period using meal replacement products, subjects losing ≥ 8% of their initial body weight were randomized to one of three protein supplements or maltodextrin for a 24-week weight maintenance period. Habitual diet was consumed along with the supplements expected to constitute 10-15% of total energy. For this analysis we stratified the participants into low and high strata based on median values of pre-intervention P/B ratio, pre-weight loss Homeostatic model assessment of insulin resistance (HOMA-IR) (<2.33 or > 2.33), and dietary fiber intake during the intervention (< 28.5 or > 28.5 g/10 MJ).

RESULTS

Regardless of weight maintenance regimen, subjects with high P/B ratio (n = 63) regained 1.5 (95% CI 0.4, 2.7) kg body weight (P = 0.007) more than subjects with low P/B ratio (n = 63). The regain among subjects with high P/B ratio was particular evident if HOMA-IR was high and dietary fiber intake was low. Consequently, in the high P/B strata, subjects with high HOMA-IR and low fiber intake (n = 17) regained 5.3 (95% CI 3.3, 7.3) kg (P < 0.001) more body weight compared with participants with low HOMA-IR and high fiber intake (n = 16).

CONCLUSIONS

Subjects with high P/B ratio were more susceptible to regain body weight compared with subjects with low P/B ratio, especially when dietary fiber intake was low and glucose metabolism was impaired. These observations underline that both the P/B ratio and markers of glucose metabolism should be considered as important biomarkers within personalized nutrition for optimal weight management.

The effects of licogliflozin, a dual SGLT1/2 inhibitor, on body weight in obese patients with or without diabetes

BACKGROUND

There is an unmet need for a safer and more effective treatment for obesity. This study assessed the effects of licogliflozin, a dual inhibitor of sodium-glucose co-transporter (SGLT) 1/2, on body weight, metabolic parameters and incretin hormones in patients with type 2 diabetes mellitus (T2DM) and/or obesity.

METHODS

Patients with obesity (BMI, 35-50 kg/m² ) were enrolled into a 12-week study (N = 88; licogliflozin 150 mg q.d.). Patients with T2DM were enrolled into a second, two-part study, comprising a single-dose cross-over study (N = 12; 2.5 - 300 mg) and a 14-day dosing study (N = 30; 15 mg q.d). Primary endpoints included effects on body weight, effects on glucose, safety and tolerability. Secondary endpoints included urinary glucose excretion (UGE₂₄ ) and pharmacokinetics, while exploratory endpoints assessed the effects on incretin hormones (total GLP-1, PYY_3-36 , and GIP), insulin and glucagon.

RESULTS

Treatment with licogliflozin 150 mg q.d. for 12 weeks in patients with obesity significantly reduced body weight by 5.7% vs placebo (P < 0.001) and improved metabolic parameters such as significantly reduced postprandial glucose excursion (21%; P < 0.001), reduced insulin levels (80%; P < 0.001) and increased glucagon (59%; P < 0.001). In patients with T2DM, a single dose of licogliflozin 300 mg in the morning prior to an oral glucose tolerance test (OGTT) remarkably reduced glucose excursion by 93% (P < 0.001; incremental AUC_0-4h ) and suppressed insulin by 90% (P < 0.01; incremental AUC_0-4h ). Treatment with licogliflozin 15 mg q.d. for 14 days reduced 24-hour average glucose levels by 26% (41 mg/dL; P < 0.001) and increased UGE₂₄ to 100 g (P < 0.001) in patients with T2DM. In addition, this treatment regimen significantly increased total GLP-1 by 54% (P < 0.001) and PYY_3-36 by 67% (P < 0.05) post OGTT vs placebo, while significantly reducing GIP levels by 53% (P < 0.001). Treatment with licogliflozin was generally safe and well tolerated. Diarrhea (increased numbers of loose stool) was the most common adverse event in all studies (90% with licogliflozin vs 25% with placebo in the 12-week study), while a lower incidence of flatulence, abdominal pain and abdominal distension (25%-43% with licogliflozin vs 9%-11% with placebo in the 12-week study) were among the other gastrointestinal events reported.

CONCLUSION

Licogliflozin treatment (1-84 days) leads to significant weight loss and favourable changes in a variety of metabolic parameters and incretin hormones. Dual inhibition of SGLT1/2 with licogliflozin in the gut and kidneys is an attractive strategy for treating obesity and diabetes.

Dietary fat: From foe to friend?

For decades, dietary advice was based on the premise that high intakes of fat cause obesity, diabetes, heart disease, and possibly cancer. Recently, evidence for the adverse metabolic effects of processed carbohydrate has led to a resurgence in interest in lower-carbohydrate and ketogenic diets with high fat content. However, some argue that the relative quantity of dietary fat and carbohydrate has little relevance to health and that focus should instead be placed on which particular fat or carbohydrate sources are consumed. This review, by nutrition scientists with widely varying perspectives, summarizes existing evidence to identify areas of broad consensus amid ongoing controversy regarding macronutrients and chronic disease.

Pretreatment Fasting Glucose and Insulin as Determinants of Weight Loss on Diets Varying in Macronutrients and Dietary Fibers-The POUNDS LOST Study

Efforts to identify a preferable diet for weight management based on macronutrient composition have largely failed, but recent evidence suggests that satiety effects of carbohydrates may depend on the individual's insulin-mediated cellular glucose uptake. Therefore, using data from the POUNDS LOST trial, pre-treatment fasting plasma glucose (FPG), fasting insulin (FI), and homeostatic model assessment of insulin resistance (HOMA-IR) were studied as prognostic markers of long-term weight loss in four diets differing in carbohydrate, fat, and protein content, while assessing the role of dietary fiber intake. Subjects with FPG <100 mg/dL lost 2.6 (95% CI 0.9;4.4, p = 0.003) kg more on the low-fat/high-protein (n = 132) compared to the low-fat/average-protein diet (n = 136). Subjects with HOMA-IR ≥4 lost 3.6 (95% CI 0.2;7.1, p = 0.038) kg more body weight on the high-fat/high-protein (n = 35) compared to high-fat/average-protein diet (n = 33). Regardless of the randomized diet, subjects with prediabetes and FI below the median lost 5.6 kg (95% CI 0.6;10.6, p = 0.030) more when consuming ≥35 g (n = 15) compared to <35 g dietary fiber/10 MJ (n = 16). Overall, subjects with normal glycemia lost most on the low-fat/high-protein diet, subjects with high HOMA-IR lost most on the high-fat/high protein diet, and subjects with prediabetes and low FI had particular benefit from dietary fiber in the diet.

Microbial Population Changes and Their Relationship with Human Health and Disease

Specific microbial profiles and changes in intestinal microbiota have been widely demonstrated to be associated with the pathogenesis of a number of extra-intestinal (obesity and metabolic syndrome) and intestinal (inflammatory bowel disease) diseases as well as other metabolic disorders, such as non-alcoholic fatty liver disease and type 2 diabetes. Thus, maintaining a healthy gut ecosystem could aid in avoiding the early onset and development of these diseases. Furthermore, it is mandatory to evaluate the alterations in the microbiota associated with pathophysiological conditions and how to counteract them to restore intestinal homeostasis. This review highlights and critically discusses recent literature focused on identifying changes in and developing gut microbiota-targeted interventions (probiotics, prebiotics, diet, and fecal microbiota transplantation, among others) for the above-mentioned pathologies. We also discuss future directions and promising approaches to counteract unhealthy alterations in the gut microbiota. Altogether, we conclude that research in this field is currently in its infancy, which may be due to the large number of factors that can elicit such alterations, the variety of related pathologies, and the heterogeneity of the population involved. Further research on the effects of probiotics, prebiotics, or fecal transplantations on the composition of the human gut microbiome is necessary.

Personalized nutrition: pretreatment glucose metabolism determines individual long-term weight loss responsiveness in individuals with obesity on low-carbohydrate versus low-fat diet

BACKGROUND/OBJECTIVES

The interaction between fasting plasma glucose (FPG) and fasting insulin (FI) concentrations and diets with different carbohydrate content were studied as prognostic markers of weight loss as recent studies up to 6 months of duration have suggested the importance of these biomarkers.

SUBJECTS/METHODS

This was a retrospective analysis of a clinical trial where participants with obesity were randomized to an ad libitum low-carbohydrate diet or a low-fat diet with low energy content (1200-1800 kcal/day [≈ 5.0-7.5 MJ/d]; ≤ 30% calories from fat) for 24 months. Participants were categorized (pretreatment) as normoglycemic (FPG < 5.6 mmol/L) or prediabetic (FPG ≥ 5.6-6.9 mmol/L) and further stratified by median FI. Linear mixed models were used to examine outcomes by FPG and FI values.

RESULTS

After 2 years, participants with prediabetes and high FI lost 7.2  kg (95% CI 2.1;12.2, P = 0.005) more with the low-fat than low-carbohydrate diet, whereas those with prediabetes and low FI tended to lose 6.2  kg (95% CI -0.9;13.3, P = 0.088) more on the low-carbohydrate diet than low-fat diet [mean difference: 13.3 kg (95% CI 4.6;22.0, P = 0.003)]. No differences between diets were found among participants with normoglycemia and either high or low FI (both P ≥ 0.16).

CONCLUSIONS

Fasting plasma glucose and insulin are strong predictors of the weight loss response to diets with different macronutrient composition and might be a useful approach for personalized weight management.