Effect of a Very-Low-Calorie Ketogenic Diet on Circulating Myokine Levels Compared with the Effect of Bariatric Surgery or a Low-Calorie Diet in Patients with Obesity

Impact of bariatric surgery on circulating irisin levels: a systematic review and meta‑analysis

This systematic review and meta-analysis evaluated changes in circulating irisin levels after bariatric surgery. A systematic search was performed across Embase, Scopus, PubMed, and Web of Science for this study. The meta-analysis was conducted using Comprehensive Meta-Analysis (CMA) V4 software. The overall effect size was depicted through a random-effects meta-analysis and the leave-one-out method. The meta-analysis, which included 13 studies with a total of 407 participants, showed a statistically non-significant reduction in circulating irisin levels following bariatric surgery (SMD:  - 0.089, 95% CI  - 0.281, 0.102, 95% PI:  - 0.790, 0.611, p = 0.360; I2:70.56). Our research found no significant change in irisin levels after bariatric surgery. Moreover, these findings were not associated with the type of surgery or the duration of follow-up.

Caloric restriction, Sirtuins, and cardiovascular diseases

ABSTRACT

Caloric restriction (CR) is a well-established dietary intervention known to extend healthy lifespan and exert positive effects on aging-related diseases, including cardiovascular conditions. Sirtuins, a family of nicotinamide adenine dinucleotide (NAD + )-dependent histone deacetylases, have emerged as key regulators of cellular metabolism, stress responses, and the aging process, serving as energy status sensors in response to CR. However, the mechanism through which CR regulates Sirtuin function to ameliorate cardiovascular disease remains unclear. This review not only provided an overview of recent research investigating the interplay between Sirtuins and CR, specifically focusing on their potential implications for cardiovascular health, but also provided a comprehensive summary of the benefits of CR for the cardiovascular system mediated directly via Sirtuins. CR has also been shown to have considerable impact on specific metabolic organs, leading to the production of small molecules that enter systemic circulation and subsequently regulate Sirtuin activity within the cardiovascular system. The direct and indirect effects of CR offer a potential mechanism for Sirtuin modulation and subsequent cardiovascular protection. Understanding the interplay between CR and Sirtuins will provide new insights for the development of interventions to prevent and treat cardiovascular diseases.

Effects of low fat diet on inflammatory parameters in individuals with obesity/overweight and non-alcoholic fatty liver disease: A cross-sectional study

Nonalcoholic fatty liver disease (NAFLD) is considered one of the most important causes of chronic liver disorders in the world. Dietary pattern is a modifiable risk factor that represents the main target for the prevention and treatment of NAFLD. The aim of this cross-sectional study was to assess the impact of low-fat diet on anthropometric measurements, biochemical, and inflammatory parameters in individuals with obesity/overweight and NAFLD. A total of 108 individuals (n = 59 males and n = 49 females) aged between 19 and 65 years participated in the 12-week weight loss program. Dietary treatment plans including low-fat diets were randomly prescribed for each individual. Anthropometric measurements were collected by a trained dietitian at baseline and 12-week follow-up. Blood samples were collected for each individual at baseline and 3rd month for biochemical measurements and enzyme-linked immunosorbent assay analysis for tumor necrosis factor-α (TNF-α), interleukin (IL)-6, fibroblast growth factor-21 (FGF-21), chemerin, and irisin levels in plasma. At the end of the study, body weight, body mass index, body fat % body fat mass (kg) reduced significantly in females and males (P < .05). Moreover, reductions in waist, hip, and neck circumferences were significant in both groups. Changes in alanine aminotransferase and aspartate aminotransferase levels were significant in 3rd month. After 3 months, reductions in TNF-α, IL-6, and FGF-21 levels were significant in individuals with obesity/overweight and NAFLD. While no significant change in chemerin and irisin levels was found. These results show that low-fat diet over a 12-week period led to improvements in both anthropometric measurements and biochemical parameters in individuals with obesity/overweight and NAFLD.

Effects of a two meals-a-day ketogenic diet on newly diagnosed obese patients with type 2 diabetes mellitus: A retrospective observational study

To investigate the effects of a two-meals-a-day energy-restricted ketogenic diet (KD) on newly diagnosed obese patients with type 2 diabetes mellitus. In total, 60 obese patients with newly diagnosed type 2 diabetes mellitus were divided into 2 groups: 1 group followed a 2-meals-a-day KD and the other group followed a conventional diabetic diet. Changes in weight, blood glucose, blood lipids, insulin resistance, and uric acid levels were observed before and after 2 months of adhering to the respective diets under energy restriction. Both groups showed significant reductions in weight, waist circumference, body mass index, total cholesterol, triglycerides, high-density lipoproteins, low-density lipoproteins, fasting blood glucose, fasting insulin, and glycated hemoglobin (P < .05). The twice-daily KD group showed more significant improvements in these parameters compared to the conventional diabetic diet group. In addition, the 2-meals-a-day KD group showed a slight increase in uric acid levels compared to the conventional diabetic diet control group (P < .05). The 2-meals-a-day KD can significantly improve weight, blood glucose, and lipid control in newly diagnosed obese patients with type 2 diabetes mellitus.

Effects of ketone bodies on energy expenditure, substrate utilization, and energy intake in humans

The potential of ketogenic approaches to regulate energy balance has recently gained attention since ketones may influence both energy expenditure and energy intake. In this narrative review, we summarized the most relevant evidence about the role of ketosis on energy expenditure, substrate utilization, and energy intake in humans. We considered different strategies to induce ketosis, such as fasting, dietary manipulation, and exogenous ketone sources. In general, ketosis does not have a major influence on energy expenditure but promotes a shift in substrate utilization towards ketone body oxidation. The strategies to induce ketosis by reduction of dietary carbohydrate availability (e.g., ketogenic diets) do not independently influence energy intake, being thus equally effective for weight loss as diets with higher carbohydrate content. In contrast, the intake of medium-chain triglycerides and ketone esters induces ketosis and appears to increase energy expenditure and reduce energy intake in the context of high carbohydrate availability. These latter strategies lead to slightly enhanced weight loss. Unfortunately, distinguishing the effects of the various ketogenic strategies per se from the effects of other physiological responses is not possible with the available human data. Highly controlled, inpatient studies using targeted strategies to isolate the independent effects of ketones are required to adequately address this knowledge gap.

Chronotype as a predictor of weight loss and body composition improvements in women with overweight or obesity undergoing a very low-calorie ketogenic diet (VLCKD)

BACKGROUND & AIM

Recent studies reported that chronotype play a role in the development of metabolic comorbidities and in determining dietary habits in obesity. However, little is known if chronotype could predict the efficacy of nutritional approaches for obesity. The aim of this study was to investigate whether chronotype categories can have a role in determining the efficacy of very low-calorie ketogenic diet (VLCKD) in terms of weight loss and changes of body composition in women with overweight or obesity.

METHODS

In this retrospective study we analyzed data from 248 women (BMI 36.03 ± 5.20 kg/m2, aged 38.76 ± 14.05 years) clinically referred for weight loss and who completed a VLCKD program. In all women, we assessed anthropometric parameters (weight, height, and waist circumference), body composition and phase angle (through bioimpedance analysis, Akern BIA 101) at the baseline and after 31 days of active phase of VLCKD. Chronotype score was assessed using Morningness-Eveningness questionnaire (MEQ) at baseline.

RESULTS

After 31 days of active phase of VLCKD all enrolled women experienced significant weight loss (p < 0.001) and reduction of BMI (p < 0.001), waist circumference (p < 0.001), fat mass (kg and %) (p < 0.001), and free fat mass (kg) (p < 0.001). Women with evening chronotype experienced significantly less weight loss (p < 0.001) and reduced fat mass (kg and %) (p < 0.001), increased fat free mass (kg and %) (p < 0.001) and phase angle (p < 0.001) than women with morning chronotype. In addition, chronotype score correlated negatively with percentage changes in weight (p < 0.001), BMI (p < 0.001), waist circumference (p < 0.001) and fat mass (p < 0.001) and positively with fat free mass (p < 0.001) and phase angle (p < 0.001) from baseline to the 31st day of active phase of VLCKD. Using a linear regression model, chronotype score (p < 0.001) was the main predictors of weight loss achieved with VLCKD.

CONCLUSION

Evening chronotype is associated with a lower efficacy in terms of weight loss and improvements of body composition after VLCKD in obesity.

Short-time effects of ketogenic diet or modestly hypocaloric Mediterranean diet on overweight and obese women with polycystic ovary syndrome

INTRODUCTION

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women during reproductive age. It is characterized clinically by oligo-ovulation or anovulation, hyper-androgenism, and the presence of polycystic ovaries. Often comorbid with insulin resistance, dyslipidemia, and obesity, it also carries significant risk for the development of cardio-vascular and metabolic sequelae, including diabetes and metabolic syndrome. In light of these evidences, the most therapeutic option prescribed to PCOS women with obesity, regardless of the phenotype from the severity of clinical expression, is lifestyle correction by diet and physical activity.

PURPOSE

The aim of this study was to evaluate the association between PCOS with KD in overweight and/or obese women with PCOS, and evaluate the possible beneficial effects on metabolic and endocrine parameters, compared to a standard, balanced hypocaloric diet such as Mediterranean diet (MD).

METHODS

Participants were assigned to receive, in a 1:1 ratio, one of the two following dietary sequences: KD or MD. In all subjects anthropometric parameters, body composition and metabolic and endocrine parameters were obtained at baseline and after dietetic treatment.

RESULTS

Our results showed a significant change in the anthropometric and biochemical parameters in both groups after both diet therapies, with statistically significant differences (p < 0.001). Though, the reductions of all parameters were significantly greater in KD group than in MD group.

CONCLUSION

Our results suggest that a reduction of dietary intake of carbohydrates by KD may be considered as a valuable non-pharmacological treatment for PCOS.

Different Effects of Cyclical Ketogenic vs. Nutritionally Balanced Reduction Diet on Serum Concentrations of Myokines in Healthy Young Males Undergoing Combined Resistance/Aerobic Training

Myokines represent important regulators of muscle metabolism. Our study aimed to explore the effects of a cyclical ketogenic reduction diet (CKD) vs. a nutritionally balanced reduction diet (RD) combined with regular resistance/aerobic training in healthy young males on serum concentrations of myokines and their potential role in changes in physical fitness. Twenty-five subjects undergoing regular resistance/aerobic training were randomized to the CKD (n = 13) or RD (n = 12) groups. Anthropometric and spiroergometric parameters, muscle strength, biochemical parameters, and serum concentrations of myokines and cytokines were assessed at baseline and after 8 weeks of intervention. Both diets reduced body weight, body fat, and BMI. Muscle strength and endurance performance were improved only by RD. Increased musclin (32.9 pg/mL vs. 74.5 pg/mL, p = 0.028) and decreased osteonectin levels (562 pg/mL vs. 511 pg/mL, p = 0.023) were observed in RD but not in the CKD group. In contrast, decreased levels of FGF21 (181 pg/mL vs. 86.4 pg/mL, p = 0.003) were found in the CKD group only. Other tested myokines and cytokines were not significantly affected by the intervention. Our data suggest that changes in systemic osteonectin and musclin levels could contribute to improved muscle strength and endurance performance and partially explain the differential effects of CKD and RD on physical fitness.

Skeletal Muscle Myokine Expression in Critical Illness, Association With Outcome and Impact of Therapeutic Interventions

Context

Muscle expresses and secretes several myokines that bring about benefits in distant organs.

Objective

We investigated the impact of critical illness on muscular expression of irisin, kynurenine aminotransferases, and amylase; association with clinical outcome; and impact of interventions that attenuate muscle wasting/weakness.

Methods

We studied critically ill patients who participated in 2 randomized controlled trials (EPaNIC/NESCI) and documented time profiles in critically ill mice. Included in the study were 174 intensive care unit (ICU) patients (day 8 ± 1) vs 19 matched controls, and 60 mice subjected to surgery/sepsis vs 60 pair-fed healthy mice. Interventions studied included 7-day neuromuscular electrical stimulation (NMES), and withholding parenteral nutrition (PN) in the first ICU week (late PN) vs early PN. The main outcome measures were FNDC5 (irisin- precursor), KYAT1, KYAT3, and amylase mRNA expression in skeletal muscle.

Results

Critically ill patients showed 34% to 80% lower mRNA expression of FNDC5, KYAT1, and amylases than controls (P < .0001). Critically ill mice showed time-dependent reductions in all mRNAs compared with healthy mice (P ≤ .04). The lower FNDC5 expression in patients was independently associated with a higher ICU mortality (P = .015) and ICU-acquired weakness (P = .012), whereas the lower amylase expression in ICU survivors was independently associated with a longer ICU stay (P = .0060). Lower amylase expression was independently associated with a lower risk of death (P = .048), and lower KYAT1 expression with a lower risk of weakness (P = .022). NMES increased FNDC5 expression compared with unstimulated muscle (P = .016), and late PN patients had a higher KYAT1 expression than early PN patients (P = .022).

Conclusion

Expression of the studied myokines was affected by critical illness and associated with clinical outcomes, with limited effects of interventions that attenuate muscle wasting or weakness.

Effects of an exogenous ketone ester using multi-omics in skeletal muscle of aging C57BL/6J male mice

Exogenous ketone ester supplementation provides a means to increase circulating ketone concentrations without the dietary challenges imposed by ketogenic diets. Our group has shown that oral R,S-1,3, butanediol diacetoacetate (BD-AcAc2) consumption results in body weight loss or maintenance with moderate increases in circulating ketones. We have previously shown a diet consisting of 25% BD-AcAc2 can maintain lean body mass (LBM) and induce fat mass (FM) loss in young, healthy male mice, but the underlying mechanisms are still unknown. Therefore, the purpose of this study was to determine if a diet consisting of 25% BD-AcAc2 (ketone ester, KE) would alter body composition, transcriptional regulation, the proteome, and the lipidome of skeletal muscle in aged mice. We hypothesized that the KE group would remain weight stable with improvements in body composition compared to controls, resulting in a healthy aging phenotype. Male C57BL/6J mice (n = 16) were purchased from Jackson Laboratories at 72 weeks of age. After 1 week of acclimation, mice were weighed and randomly assigned to one of two groups (n = 8 per group): control (CON) or KE. A significant group by time interaction was observed for body weight (P &lt; 0.001), with KE fed mice weighing significantly less than CON. FM increased over time in the control group but was unchanged in the KE group. Furthermore, LBM was not different between CON and KE mice despite KE mice weighing less than CON mice. Transcriptional analysis of skeletal muscle identified 6 genes that were significantly higher and 21 genes that were significantly lower in the KE group compared to CON. Lipidomic analysis of skeletal muscle identified no differences between groups for any lipid species, except for fatty acyl chains in triacylglycerol which was 46% lower in the KE group. Proteomics analysis identified 44 proteins that were different between groups, of which 11 were lower and 33 were higher in the KE group compared to CON. In conclusion, 72-week-old male mice consuming the exogenous KE, BD-AcAc2, had lower age-related gains in body weight and FM compared to CON mice. Furthermore, transcriptional and proteomics data suggest a signature in skeletal muscle of KE-treated mice consistent with markers of improved skeletal muscle regeneration, improved electron transport chain utilization, and increased insulin sensitivity.

The Effect of the Restrictive Ketogenic Diet on the Body Composition, Haematological and Biochemical Parameters, Oxidative Stress and Advanced Glycation End-Products in Young Wistar Rats with Diet-Induced Obesity

Over the past few years, the interest in the application of the ketogenic diet (KD) for obesity management is growing. Although many studies have been performed on the effects of KD, the metabolic and physiological impact of KD is still not fully understood. Therefore, this study aimed to evaluate the effect of calorie-restricted KD on the body weight and composition, oxidative stress, and advanced glycation end products (AGEs) assessed in an animal model with young Wistar rats. KD was followed for 4 weeks in maturity after an obesity-inducing high-fat diet during adolescence, resulting in a slowing down of the weight gain but higher adiposity compared to a standard diet. Increased adiposity resulted in an deterioration of liver parameters, suggesting negative changes in this organ. No adverse effects of KD were determined in haematological parameters in young rats. KD did not affect AGEs; however, a decrease in oxidative stress was observed. Based on the presented results, it can be concluded that KD applied for weight loss in obesity induced in adolescence may reduce oxidative stress without compromising the haematological status; however, caution may be required to control adiposity, glucose level and liver health. Thus, KD therapy should be carefully controlled, especially in young subjects.

The effect of coconut oil on anthropometric measurements and irisin levels in overweight individuals

AIM

This study aimed to discover the effects of coconut oil intake and diet therapy on anthropometric measurements, biochemical findings and irisin levels in overweight individuals.

MATERIALS AND METHODS

Overweight individuals (n = 44, 19-30 years) without any chronic disease were included. In this randomized controlled crossover study, the participants were divided into two groups (Group 1: 23 people, Group 2: 21 people). In the first phase, Group 1 received diet therapy to lose 0.5-1 kg of weight per week and 20 mL of coconut oil/day, while Group 2 only received diet therapy. In the second phase, Group 1 received diet therapy while Group 2 received diet therapy and 20 mL of coconut oil/day. Anthropometric measurements were taken four times. Irisin was measured four times by enzyme-linked immunosorbent (ELISA) method and other biochemical findings were measured twice. Statistical analysis was made on SPSS 20.

RESULTS

The irisin level decreased significantly when the participants only took coconut oil (p ≤ 0.05). There was a significant decrease in the participants' body weight, body mass index (BMI) level and body fat percentage (p ≤ 0.01). Insulin, total cholesterol, low density lipoproteins (LDL) cholesterol, and triglyceride (TG) levels of all participants decreased significantly (p ≤ 0.05). There was no significant difference in irisin level due to body weight loss (p ≤ 0.05); coconut oil provided a significant decrease in irisin level (p ≤ 0.05).

CONCLUSION

Diet therapy and weight loss did not have an effect on irisin level, but coconut oil alone was found to reduce irisin level. Coconut oil had no impact on anthropometric and biochemical findings.

Changes of Circulating Irisin and High-Sensitivity C-Reactive Protein Levels in Morbidly Obese Individuals with Type 2 Diabetes After Roux-en-Y Gastric Bypass

Background: Irisin has been recently reported to provide beneficial effects in obesity and diabetes. Elevation of high-sensitivity C-reactive protein (hs-CRP) reflects the inflammatory state that has been shown to play a key role in obesity and its comorbidities. Objective: Our study aimed to compare the changes of circulating irisin levels in an obese diabetic population who underwent laparoscopic Roux-en-Y gastric bypass (LRYGB) versus a control-matched population who underwent usual medical care plus diabetes support education (DSE) program. In addition, we aimed to explore the association between circulating irisin and hs-CRP levels after the interventions. Methods: In a prospective controlled trial, we studied 58 obese individuals with type 2 diabetes before and 12 months after intervention. Twenty-nine subjects underwent LRYGB and 29 subjects received DSE. Results: At 12-month follow-up, compared with the DSE group, patients who underwent LRYGB lost more weight (LRYGB; -33.4 ± 11.2, and DSE; 0.2 ± 4.9 kg; P < .001), fat mass (P < .001), and fat-free mass (P < .05). Circulating irisin (P < .05) and hs-CRP level (P < .05) were also significantly lower. Within the LRYGB group, the reduction of irisin level was positively associated with the changes of hs-CRP levels (r = 0.39, P < .05). Conclusions: To the best of our knowledge, this is the first study showing that LRYGB significantly reduces circulating irisin levels compared with usual medical care and DSE, in an obese diabetic population. After LRYGB, the irisin reduction significantly correlates with the reduction of hs-CRP. The elevation of circulating irisin levels suggests irisin resistance in the obese state and its decrease after LRYGB might reflect the resolution of irisin resistance. Future investigations are needed to confirm and explore the mechanisms of irisin resistance in obesity, its resolution after LRYGB, and the pathophysiological significance.

Adipose tissue and blood leukocytes ACE2 DNA methylation in obesity and after weight loss

BACKGROUND

Obesity was consistently associated with a poor prognosis in patients with COVID-19. Epigenetic mechanisms were proposed as the link between obesity and comorbidities risk.

AIM

To evaluate the methylation levels of angiotensin-converting enzyme 2 (ACE2) gene, the main entry receptor of SARS-CoV-2, in different depots of adipose tissue (AT) and leukocytes (PBMCs) in obesity and after weight loss therapy based on a very-low-calorie ketogenic diet (VLCKD), a balanced hypocaloric diet (HCD) or bariatric surgery (BS).

MATERIALS AND METHODS

DNA methylation levels of ACE2 were extracted from our data sets generated by the hybridization of subcutaneous (SAT) (n = 32) or visceral (VAT; n = 32) adipose tissue, and PBMCs (n = 34) samples in Infinium HumanMethylation450 BeadChips. Data were compared based on the degree of obesity and after 4-6 months of weight loss either by following a nutritional or surgical treatment and correlated with ACE2 transcript levels.

RESULTS

As compared with normal weight, VAT from patients with obesity showed higher ACE2 methylation levels. These differences were mirrored in PBMCs but not in SAT. The observed obesity-associated methylation of ACE2 was reversed after VLCKD and HCD but not after BS. Among the studied CpG sites, cg16734967 and cg21598868, located at the promoter, were the most affected and correlated with BMI. The observed DNA methylation pattern was inversely correlated with ACE2 expression.

CONCLUSION

Obesity-related VAT shows hypermethylation and downregulation of the ACE2 gene that is mirrored in PBMCs and is restored after nutritional weight reduction therapy. The results warrant the necessity to further evaluate its implication for COVID-19 pathogenesis.

The magnitude and progress of lean body mass, fat-free mass, and skeletal muscle mass loss following bariatric surgery: A systematic review and meta-analysis

Postbariatric loss of muscle tissue could negatively affect long-term health due to its role in various bodily processes, such as metabolism and functional capacity. This meta-analysis aimed to unravel time-dependent changes in the magnitude and progress of lean body mass (LBM), fat-free mass (FFM), and skeletal muscle mass (SMM) loss following bariatric surgery. A systematic literature search was conducted in Pubmed, Embase, and Web of Science. Fifty-nine studies assessed LBM (n = 37), FFM (n = 20), or SMM (n = 3) preoperatively and ≥1 time points postsurgery. Random-effects meta-analyses were performed to determine pooled loss per outcome parameter and follow-up time point. At 12-month postsurgery, pooled LBM loss was -8.13 kg [95%CI -9.01; -7.26]. FFM loss and SMM loss were -8.23 kg [95%CI -10.74; -5.73] and -3.18 kg [95%CI -5.64; -0.71], respectively. About 55% of 12-month LBM loss occurred within 3-month postsurgery, followed by a more gradual decrease up to 12 months. Similar patterns were seen for FFM and SMM. In conclusion, >8 kg of LBM and FFM loss was observed within 1-year postsurgery. LBM, FFM, and SMM were predominantly lost within 3-month postsurgery, highlighting that interventions to mitigate such losses should be implemented perioperatively.

Ketone bodies: from enemy to friend and guardian angel

During starvation, fasting, or a diet containing little digestible carbohydrates, the circulating insulin levels are decreased. This promotes lipolysis, and the breakdown of fat becomes the major source of energy. The hepatic energy metabolism is regulated so that under these circumstances, ketone bodies are generated from β-oxidation of fatty acids and secreted as ancillary fuel, in addition to gluconeogenesis. Increased plasma levels of ketone bodies thus indicate a dietary shortage of carbohydrates. Ketone bodies not only serve as fuel but also promote resistance to oxidative and inflammatory stress, and there is a decrease in anabolic insulin-dependent energy expenditure. It has been suggested that the beneficial non-metabolic actions of ketone bodies on organ functions are mediated by them acting as a ligand to specific cellular targets. We propose here a major role of a different pathway initiated by the induction of oxidative stress in the mitochondria during increased ketolysis. Oxidative stress induced by ketone body metabolism is beneficial in the long term because it initiates an adaptive (hormetic) response characterized by the activation of the master regulators of cell-protective mechanism, nuclear factor erythroid 2-related factor 2 (Nrf2), sirtuins, and AMP-activated kinase. This results in resolving oxidative stress, by the upregulation of anti-oxidative and anti-inflammatory activities, improved mitochondrial function and growth, DNA repair, and autophagy. In the heart, the adaptive response to enhanced ketolysis improves resistance to damage after ischemic insults or to cardiotoxic actions of doxorubicin. Sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors may also exert their cardioprotective action via increasing ketone body levels and ketolysis. We conclude that the increased synthesis and use of ketone bodies as ancillary fuel during periods of deficient food supply and low insulin levels causes oxidative stress in the mitochondria and that the latter initiates a protective (hormetic) response which allows cells to cope with increased oxidative stress and lower energy availability. KEYWORDS: Ketogenic diet, Ketone bodies, Beta hydroxybutyrate, Insulin, Obesity, Type 2 diabetes, Inflammation, Oxidative stress, Cardiovascular disease, SGLT2, Hormesis.

Impact of Bariatric Surgery on Adipose Tissue Biology

Bariatric surgery (BS) procedures are actually the most effective intervention to help subjects with severe obesity achieve significant and sustained weight loss. White adipose tissue (WAT) is increasingly recognized as the largest endocrine organ. Unhealthy WAT expansion through adipocyte hypertrophy has pleiotropic effects on adipocyte function and promotes obesity-associated metabolic complications. WAT dysfunction in obesity encompasses an altered adipokine secretome, unresolved inflammation, dysregulated autophagy, inappropriate extracellular matrix remodeling and insufficient angiogenic potential. In the last 10 years, accumulating evidence suggests that BS can improve the WAT function beyond reducing the fat depot sizes. The causal relationships between improved WAT function and the health benefits of BS merits further investigation. This review summarizes the current knowledge on the short-, medium- and long-term outcomes of BS on the WAT composition and function.

Measuring ketone bodies for the monitoring of pathologic and therapeutic ketosis

BACKGROUND

The ketone bodies β-hydroxybutyrate (BOHB) and acetone are generated as a byproduct of the fat metabolism process. In healthy individuals, ketone body levels are ∼0.1 mM for BOHB and ∼1 part per million for breath acetone (BrAce). These levels can increase dramatically as a consequence of a disease process or when used therapeutically for disease treatment. For example, increased ketone body concentration during weight loss is an indication of elevated fat metabolism. Ketone body measurement is relatively inexpensive and can provide metabolic insights to help guide disease management and optimize weight loss.

METHODS

This review of the literature provides metabolic mechanisms and typical concentration ranges of ketone bodies, which can give new insights into these conditions and rationale for measuring ketone bodies.

RESULTS

Diseases such as heart failure and ketoacidosis can affect caloric intake and macronutrient management, which can elevate BOHB 30-fold and BrAce 1000-fold. Other diseases associated with obesity, such as brain dysfunction, cancer, and diabetes, may cause dysfunction because of an inability to use glucose, excessive reliance on glucose, or poor insulin signaling. Elevating ketone body concentrations (e.g., nutritional ketosis) may improve these conditions by forcing utilization of ketone bodies, in place of glucose, for fuel. During weight loss, monitoring ketone body concentration can demonstrate program compliance and can be used to optimize the weight-loss plan.

CONCLUSIONS

The role of ketone bodies in states of pathologic and therapeutic ketosis indicates that accurate measurement and monitoring of BOHB or BrAce will likely improve disease management. Bariatric surgery is examined as a case study for monitoring both types of ketosis.

Variation in myokine and adipokine levels according to menstrual cycle following regular resistance exercise

BACKGROUND

The purpose of this study was to analyze the differences between myokine and adipokine factors under stable conditions according to the menstrual cycle (luteal and follicular phases), and investigate the effect of regular resistance exercise on the changes in myokine and adipokine factors according to menstrual cycle in obese female college students.

METHODS

The study participants were female college students with a body fat percentage of 30% or more (n = 20), divided into two groups: luteal phase (n = 12) and follicular phase (n = 8). They performed regular resistance exercise three times a week, 60 minutes daily, for 16 weeks. Parameters measured include body composition via impedance, visceral fat area using computed tomography and myokine and adipokine factors in blood.

RESULTS

Levels of BDNF (p < .05), NGF (p < .01), and adiponectin (p < .01) were significantly increased in the luteal phase group after 16 weeks relative to the baseline values. Leptin (p < .01) was significantly decreased in the luteal phase group after 16 weeks. Weight, body mass index, % fat, and visceral fat area were significantly decreased in both groups after 16 weeks. Muscle mass was significantly increased in both groups after 16 weeks.

CONCLUSIONS

Regular resistance exercise affected the reduction in visceral fat area and had a positive effect on body composition, which might be altered favorably by myokines and adipokines. Thus, the timing of blood collection is very important in obese female college students.

Fibronectin type III domain-containing 5 in cardiovascular and metabolic diseases: a promising biomarker and therapeutic target

Cardiovascular and metabolic diseases are the leading causes of death and disability worldwide and impose a tremendous socioeconomic burden on individuals as well as the healthcare system. Fibronectin type III domain-containing 5 (FNDC5) is a widely distributed transmembrane glycoprotein that can be proteolytically cleaved and secreted as irisin to regulate glycolipid metabolism and cardiovascular homeostasis. In this review, we present the current knowledge on the predictive and therapeutic role of FNDC5 in a variety of cardiovascular and metabolic diseases, such as hypertension, atherosclerosis, ischemic heart disease, arrhythmia, metabolic cardiomyopathy, cardiac remodeling, heart failure, diabetes mellitus, and obesity.

Targeting obesity-related dysfunction in hormonally driven cancers

Obesity is a risk factor for at least 13 different types of cancer, many of which are hormonally driven, and is associated with increased cancer incidence and morbidity. Adult obesity rates are steadily increasing and a subsequent increase in cancer burden is anticipated. Obesity-related dysfunction can contribute to cancer pathogenesis and treatment resistance through various mechanisms, including those mediated by insulin, leptin, adipokine, and aromatase signalling pathways, particularly in women. Furthermore, adiposity-related changes can influence tumour vascularity and inflammation in the tumour microenvironment, which can support tumour development and growth. Trials investigating non-pharmacological approaches to target the mechanisms driving obesity-mediated cancer pathogenesis are emerging and are necessary to better appreciate the interplay between malignancy, adiposity, diet and exercise. Diet, exercise and bariatric surgery are potential strategies to reverse the cancer-promoting effects of obesity; trials of these interventions should be conducted in a scientifically rigorous manner with dose escalation and appropriate selection of tumour phenotypes and have cancer-related clinical and mechanistic endpoints. We are only beginning to understand the mechanisms by which obesity effects cell signalling and systemic factors that contribute to oncogenesis. As the rates of obesity and cancer increase, we must promote the development of non-pharmacological lifestyle trials for the treatment and prevention of malignancy.

Metabolic shift precedes the resolution of inflammation in a cohort of patients undergoing bariatric and metabolic surgery

Bariatric and metabolic surgery has shown to promote weight loss and reduce systemic inflammation. However, the sequence and timing of events regarding metabolic improvement and inflammation resolution has been rarely explored. Furthermore, data on inflammatory markers of Th17 and Th1 cell responses after bariatric surgery is scarce. We conducted a prospective study in subjects with obesity that underwent bariatric and metabolic surgery, with follow-ups at 3 and 6 months. Anthropometric and metabolic markers such as insulin levels, HOMA-IR, and lipid parameters declined significantly 3 months after surgery; while hs-CRP, TNF-α, IL-1β, IL-6, and IL-8 serum concentrations decreased 6 months after the procedure. Concentrations of Th1 signature and driver cytokines, particularly IFN-γ, IL-12, and IL-18, and of Th17 driver IL-23 also decreased significantly after 6 months. Significant positive correlations between triglyceride levels and hs-CRP, IL-1β, and IFN-γ concentrations, and between Apo B and IFN-γ levels were observed 6 months after bariatric and metabolic surgery. In addition, BMI was associated with hs-CRP and TNF-α concentrations. Fat mass correlated with hs-CRP, TNF-α, and IL-12. Analysis of the temporality of metabolic and inflammatory events suggests that improvement in the metabolic status occurs before resolution of systemic inflammation and may be a requisite for the later event.

How Does Fat Mass Change in the First Year After Bariatric Surgery? A Systemic Review and Meta-Analysis

This systematic review and meta-analysis investigated the time-course effect of different type of bariatric surgeries (BS) up to 1 year post-surgery on fat mass (FM) and body fat percentage (BFP) in patients with morbid obesity. We searched PubMed, Scopus, EMBASE, ISI web of science, and Cochrane databases from October 2002 until May 2020 with no restriction in the English language, to find studies examining the effect of BS on FM (kg) and BFP (%) in morbid obese patients. Meta-analysis of 103 studies carried out on data of 18,166 and 14,575 morbid obese patients following BS, showed that BS was associated with a substantial decrease in FM and BFP, respectively, in 1 month (- 8.17 kg [95% CI - 9.07, - 7.27] and - 1.51% [95% CI - 2.56, - 0.46]), 3 months (- 15.75 [95% CI - 17.49, - 14.0] and - 4.90 [95% CI - 5.97, - 3.83]), 6 months (- 22.51 [95% CI - 23.93, - 21.09] and - 8.56% [95% CI - 9.63, - 7.49]), and 12 months (- 29.69 [95% CI - 31.3, - 28.09] and - 13.49% [95% CI - 14.52, - 12.40]) after the surgery. In conclusion, BS was associated with sustained declines in FM and BFP, from 1 to 12 months, with no indication of plateau phase post-surgery post-operatively. The present study emphasizes that post-bariatric care should have more focus on FM loss during 1-year post-surgery to identify the patients at risk for fat loss plateau.

Epigenetic landscape in blood leukocytes following ketosis and weight loss induced by a very low calorie ketogenic diet (VLCKD) in patients with obesity

BACKGROUND

The molecular mechanisms underlying the potential health benefits of a ketogenic diet are unknown and could be mediated by epigenetic mechanisms.

OBJECTIVE

To identify the changes in the obesity-related methylome that are mediated by the induced weight loss or are dependent on ketosis in subjects with obesity underwent a very-low calorie ketogenic diet (VLCKD).

METHODS

Twenty-one patients with obesity (n = 12 women, 47.9 ± 1.02 yr, 33.0 ± 0.2 kg/m²) after 6 months on a VLCKD and 12 normal weight volunteers (n = 6 women, 50.3 ± 6.2 yrs, 22.7 ± 1.5 kg/m²) were studied. Data from the Infinium MethylationEPIC BeadChip methylomes of blood leukocytes were obtained at time points of ketotic phases (basal, maximum ketosis, and out of ketosis) during VLCKD (n = 10) and at baseline in volunteers (n = 12). Results were further validated by pyrosequencing in representative cohort of patients on a VLCKD (n = 18) and correlated with gene expression.

RESULTS

After weight reduction by VLCKD, differences were found at 988 CpG sites (786 unique genes). The VLCKD altered methylation levels in patients with obesity had high resemblance with those from normal weight volunteers and was concomitant with a downregulation of DNA methyltransferases (DNMT)1, 3a and 3b. Most of the encoded genes were involved in metabolic processes, protein metabolism, and muscle, organ, and skeletal system development. Novel genes representing the top scoring associated events were identified, including ZNF331, FGFRL1 (VLCKD-induced weight loss) and CBFA2T3, C3orf38, JSRP1, and LRFN4 (VLCKD-induced ketosis). Interestingly, ZNF331 and FGFRL1 were validated in an independent cohort and inversely correlated with gene expression.

CONCLUSIONS

The beneficial effects of VLCKD therapy on obesity involve a methylome more suggestive of normal weight that could be mainly mediated by the VLCKD-induced ketosis rather than weight loss.

European Guidelines for Obesity Management in Adults with a Very Low-Calorie Ketogenic Diet: A Systematic Review and Meta-Analysis

BACKGROUND

The very low-calorie ketogenic diet (VLCKD) has been recently proposed as an appealing nutritional strategy for obesity management. The VLCKD is characterized by a low carbohydrate content (<50 g/day), 1-1.5 g of protein/kg of ideal body weight, 15-30 g of fat/day, and a daily intake of about 500-800 calories.

OBJECTIVES

The aim of the current document is to suggest a common protocol for VLCKD and to summarize the existing literature on its efficacy in weight management and weight-related comorbidities, as well as the possible side effects.

METHODS

This document has been prepared in adherence with Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Literature searches, study selection, methodology development, and quality appraisal were performed independently by 2 authors and the data were collated by means of a meta-analysis and narrative synthesis.

RESULTS

Of the 645 articles retrieved, 15 studies met the inclusion criteria and were reviewed, revealing 4 main findings. First, the VLCKD was shown to result in a significant weight loss in the short, intermediate, and long terms and improvement in body composition parameters as well as glycemic and lipid profiles. Second, when compared with other weight loss interventions of the same duration, the VLCKD showed a major effect on reduction of body weight, fat mass, waist circumference, total cholesterol and triglyceridemia as well as improved insulin resistance. Third, although the VLCKD also resulted in a significant reduction of glycemia, HbA1c, and LDL cholesterol, these changes were similar to those obtained with other weight loss interventions. Finally, the VLCKD can be considered a safe nutritional approach under a health professional's supervision since the most common side effects are usually clinically mild and easily to manage and recovery is often spontaneous.

CONCLUSIONS

The VLCKD can be recommended as an effective dietary treatment for individuals with obesity after considering potential contra-indications and keeping in mind that any dietary treatment has to be personalized. Prospero Registry: The assessment of the efficacy of VLCKD on body weight, body composition, glycemic and lipid parameters in overweight and obese subjects: a meta-analysis (CRD42020205189).

Potential effects of nutrition-based weight loss therapies in reversing obesity-related breast cancer epigenetic marks

Obesity is a modifiable risk factor of breast cancer and epigenetic marks were proposed as a relevant mechanistic link. These mechanisms can be remodelled by modifying lifestyle factors and this fact could be useful in the treatment of obesity-related breast cancer. This review aimed to reveal the current evidence on the effects of differences in body composition and lifestyle factors on the risk, treatment, and survival of breast cancer with a focus on the effects of weight loss therapies based on different nutrients, bioactive compounds, and Mediterranean and ketogenic diets to counteract obesity-related breast cancer epigenetic marks. This review was framed on the most relevant and recently published articles and abstracts selected in PubMed using key words related to epigenetics, lifestyle, dietary habits, nutrients, bioactive compounds, ketone bodies, and weight loss treatments in obesity and breast cancer. Several studies have demonstrated that lifestyle interventions, including dietary modifications towards a healthy diet pattern, are effective therapies to prevent the onset of breast cancer and to improve the survival after treatment. These therapies reduce the main factors associated with obesity that are links between adiposity and cancer, including oxidative stress, inflammation and epigenetic mechanisms. However, although sufficient evidence exists regarding the effects of nutrients, dietary patterns, and weight loss therapies to prevent breast cancer or to improve survival, the effects of these strategies on the oncological treatment response were less studied. This review summarises the current scientific evidence regarding these nutritional strategies as adjuvant therapies in the management of obesity-related breast cancer by remodelling epigenetic marks related to carcinogenesis.

Nerve injury and repair in a ketogenic milieu: A systematic review of traumatic injuries to the spinal cord and peripheral nervous tissue

Dietary interventions such as intermittent fasting and the ketogenic diet have demonstrated neuroprotective effects in various models of neurological insult. However, there has been a lack of evaluation of these interventions from a surgical perspective despite their potential to augment reparative processes that occur following nerve injury. Thus, we sought to analyze the effects of these dietary regimens on nerve regeneration and repair by critical appraisal of the literature. Following PRISMA guidelines, a systematic review was performed to identify studies published between 1950 and 2020 that examined the impact of either the ketogenic diet or intermittent fasting on traumatic injuries to the spinal cord or peripheral nerves. Study characteristics and outcomes were analyzed for each included article. A total of 1,890 articles were reviewed, of which 11 studies met inclusion criteria. Each of these articles was then assessed based on a variety of qualitative parameters, including type of injury, diet composition, timing, duration, and outcome. In total, seven articles examined the ketogenic diet, while four examined intermittent fasting. Only three studies examined peripheral nerves. Neuroprotective effects manifested as either improved histological or functional benefits in most of the included studies. Overall, we conclude that intermittent fasting and the ketogenic diet may promote neuroprotection and facilitate the regeneration and repair of nerve fibers following injury; however, lack of consistency between the studies in terms of animal models, diet compositions, and timing of dietary interventions preclude synthesis of their outcomes as a whole.

The "irisin system": From biological roles to pharmacological and nutraceutical perspectives

The scientific interest in irisin, a myokine discovered in 2012, has grown exponentially in recent years. Irisin, which is mainly produced in skeletal muscle, influences the browning process of adipose tissue and lipid and energy metabolism. Recent discoveries highlight that the potential of this hormone may have been underestimated. In the first part of this review, reports on irisin structure and molecules involved in its metabolic pathway are shown. Furthermore, data related to unclear aspects are also reported: distribution, different gene expression of its precursors in different tissues, physiological levels of circulating irisin, and pharmacokinetic and pharmacodynamic profile. The second part of this work focuses on exogenous stimuli and pharmacological agents which regulate the metabolic pathway of irisin and its serum concentration. In addition to physical exercise and exposure to low temperatures, which were early recognized as exogenous stimuli able to promote the production of this myokine, preclinical and clinical evidence demonstrates the ability of natural and synthetic molecules to interfere with this metabolic pathway. Current experimental data on irisin cannot dissolve all doubts related to this interesting molecule, but they certainly underline its potential for therapeutic purposes. Thus, identification of new pharmacological tools able to act on the irisin pathway is a challenging issue for biomedical research.

Ketotherapy as an epigenetic modifier in cancer

Epigenetic alterations in cancer play a variety of roles. Aberrant DNA methylation, as one of the epigenetic mechanisms, has been widely studied in both tumor and liquid biopsies and provide a useful bench mark for treatment response in cancer. Recently, several studies have reported an association between the type of diet and epigenetic modifications. Whereby there is a growing interest in finding the "anti-cancer diet formula", if such a thing exists. In this sense, ketogenic diets (KD) have reported potentially beneficial effects, which were able to prevent malignancies and decrease tumor growth. Some studies have even shown increased survival in cancer patients, reduced side effects of cytotoxic treatments, and intensified efficacy of cancer therapies. Although the biological mechanisms of KD are not well understood, it has been reported that KD may affect DNA methylation by modulating the expression of crucial genes involved in tumor survival and proliferation. However, there are many considerations to take into account to use ketotherapy in cancer, such as epigenetic mark, type of cancer, immunological and metabolic state or microbiota profile. In this review, we argue about ketotherapy as a potential strategy to consider as coadjuvant of cancer therapy. We will focus on mainly epigenetic mechanisms and dietary approach that could be included in the current clinical practice guidelines.

Effect of the ketogenic diet on glycemic control, insulin resistance, and lipid metabolism in patients with T2DM: a systematic review and meta-analysis

Background

At present, the beneficial effect of the ketogenic diet (KD) on weight loss in obese patients is generally recognized. However, a systematic research on the role of KD in the improvement of glycemic and lipid metabolism of patients with diabetes is still found scarce.

Methods

This meta-study employed the meta-analysis model of random effects or of fixed effects to analyze the average difference before and after KD and the corresponding 95% CI, thereby evaluating the effect of KD on T2DM.

Results

After KD intervention, in terms of glycemic control, the level of fasting blood glucose decreased by 1.29 mmol/L (95% CI: −1.78 to −0.79) on average, and glycated hemoglobin A1c by 1.07 (95% CI: −1.37 to −0.78). As for lipid metabolism, triglyceride was decreased by 0.72 (95% CI: −1.01 to −0.43) on average, total cholesterol by 0.33 (95% CI: −0.66 to −0.01), and low-density lipoprotein by 0.05 (95% CI: −0.25 to −0.15); yet, high-density lipoprotein increased by 0.14 (95% CI: 0.03−0.25). In addition, patients’ weight decreased by 8.66 (95% CI: −11.40 to −5.92), waist circumference by 9.17 (95% CI: −10.67 to −7.66), and BMI by 3.13 (95% CI: −3.31 to −2.95).

Conclusion

KD not only has a therapeutic effect on glycemic and lipid control among patients with T2DM but also significantly contributes to their weight loss.

Very-Low-Calorie Ketogenic Diets With Whey, Vegetable, or Animal Protein in Patients With Obesity: A Randomized Pilot Study

CONTEXT

We compared the efficacy, safety, and effect of 45-day isocaloric very-low-calorie ketogenic diets (VLCKDs) incorporating whey, vegetable, or animal protein on the microbiota in patients with obesity and insulin resistance to test the hypothesis that protein source may modulate the response to VLCKD interventions.

SUBJECTS AND METHODS

Forty-eight patients with obesity (19 males and 29 females, homeostatic model assessment (HOMA) index ≥ 2.5, aged 56.2 ± 6.1 years, body mass index [BMI] 35.9 ± 4.1 kg/m2) were randomly assigned to three 45-day isocaloric VLCKD regimens (≤800 kcal/day) containing whey, plant, or animal protein. Anthropometric indexes; blood and urine chemistry, including parameters of kidney, liver, glucose, and lipid metabolism; body composition; muscle strength; and taxonomic composition of the gut microbiome were assessed. Adverse events were also recorded.

RESULTS

Body weight, BMI, blood pressure, waist circumference, HOMA index, insulin, and total and low-density lipoprotein cholesterol decreased in all patients. Patients who consumed whey protein had a more pronounced improvement in muscle strength. The markers of renal function worsened slightly in the animal protein group. A decrease in the relative abundance of Firmicutes and an increase in Bacteroidetes were observed after the consumption of VLCKDs. This pattern was less pronounced in patients consuming animal protein.

CONCLUSIONS

VLCKDs led to significant weight loss and a striking improvement in metabolic parameters over a 45-day period. VLCKDs based on whey or vegetable protein have a safer profile and result in a healthier microbiota composition than those containing animal proteins. VLCKDs incorporating whey protein are more effective in maintaining muscle performance.

FNDC4, a novel adipokine that reduces lipogenesis and promotes fat browning in human visceral adipocytes

BACKGROUND

Fibronectin type IIIdomain-containing protein 4 (FNDC4) constitutes a secreted factor showing a high homology in the fibronectin type III and transmembrane domains with the exercise-associated myokine irisin (FNDC5). We sought to evaluate whether FNDC4 mimics the anti-obesity effects of FNDC5/irisin in human adipose tissue.

METHODS

Plasma and adipose tissue samples of 78 patients with morbid obesity undergoing bariatric surgery and 26 normal-weight individuals were used in the present study.

RESULTS

Plasma FNDC4 was decreased in patients with morbid obesity, related to obesity-associated systemic inflammation and remained unchanged six months after bariatric surgery. Visceral adipose tissue from patients with morbid obesity showed higher expression of FNDC4 and its putative receptor GPR116 regardless of the degree of insulin resistance. FNDC4 content was regulated by lipogenic, lipolytic and proinflammatory stimuli in human visceral adipocytes. FNDC4 reduced intracytosolic lipid accumulation and stimulated a brown-like pattern in human adipocytes, as evidenced by an upregulated expression of UCP-1 and the brown/beige adipocyte markers PRDM16, TMEM26 and CD137. Moreover, FNDC4 treatment upregulated mitochondrial DNA content and factors involved in mitochondrial biogenesis (TFAM, NRF1 and NRF2). Human FNDC4-knockdown adipocytes exhibited an increase in lipogenesis and a reduction of brown/beige-specific fat markers as well as factors involved in mitochondrial biogenesis.

CONCLUSIONS

Taken together, the novel adipokine FNDC4 reduces lipogenesis and increases fat browning in human visceral adipocytes. The upregulation of FNDC4 in human visceral fat might constitute an attempt to attenuate the adipocyte hypertrophy, inflammation and impaired beige adipogenesis in the obese state.

Myokines: a descriptive review

In the last years, scientists have shown that skeletal muscle is not a pure locomotor unit or responsible for propulsion and posture. Skeletal muscle encompasses one of the major organs of the body (constituting about 40% of the body mass in non-obese men). It regulates energy and metabolic processes and is now recognized as an organ capable of producing molecules with vital functions. These molecules are termed myokines, a new field of research in the health sciences, and represent an open field of discoveries and applications in several areas. The aim of this review was to show the role of some well-known myokines in the maintenance of homeostasis. Our search was performed in databases such as Medline/Pubmed, Embase and Scielo. Some relevant myokines are interleukin-6 (IL-6), IL-8, IL-15, irisin, myostatin, fibroblast growth factor 21 (FGF21), leukemia inhibitory factor (LIF), brain-derived neurotrophic factor (BDNF), and insulin-like growth factor-1 (IGF-1). They are related to play a positive or negative role in muscle function and metabolism homeostasis. They are associated with the regulation of glucose and lipid metabolism, the deposition of fat in the adipose tissue, and the "browning" of the white adipose tissue. For these reasons, they can interfere with the prevention of obesity, diabetes, metabolic syndrome, and cardiovascular diseases. The discovery of the myokines has opened a new direction in understanding the effects of exercises on humans.

Establishment of Adequate Nutrient Intake Criteria to Achieve Target Weight Loss in Patients Undergoing Bariatric Surgery

Although bariatric surgery is the best treatment modality for morbidly obese patients, a 10-30% rate of weight recidivism has been reported in various specialized centers. We examined changes in energy and macronutrients after bariatric surgery and performed analysis to establish appropriate nutritional guidelines for reaching the target percentage of weight loss after surgery. A total of 189 subjects who underwent bariatric surgery were classified into success and failure groups depending on whether or not they reached 50% loss of excess weight at 12 months after bariatric surgery. Physical examinations and dietary surveys were completed before and 1, 6, and 12 months after surgery. Using receiver operating characteristic (ROC) analysis, the optimal cutoff points for nutrient intakes for determining success after bariatric surgery were computed based on maximal Youden's index. At 6 and 12 months after surgery, the success group had significantly lower carbohydrate and fat intakes than the failure group. The cutoff calorie intake for success in weight loss was <835.0, <1132.5, and <1523.0 kcal/day at 1, 6, and 12 months post operation, respectively. With regard to protein, the cutoff intakes were >44.5, >41.5, and >86.5 g/day at 1, 6, and 12 months post operation, respectively. At 12 months, the cutoff ratio for energy obtained from carbohydrates, protein, and fat was <49.0, >24.5, and <28.0%, respectively. Our findings confirm that the level of diet control and nutrition restriction affect the achievement of target weight loss, emphasizing that long-term weight loss is related to compliance with nutrient recommendations.

Modification of Muscle-Related Hormones in Women with Obesity: Potential Impact on Bone Metabolism

Lean body mass (LBM) is a determinant of areal bone mineral density (aBMD) through its mechanical actions and quite possibly through its endocrine functions. The threefold aims of this study are: to determine the effects of obesity (OB) on aBMD and myokines; to examine the potential link between myokines and bone parameters; and to determine whether the effects of LBM on aBMD are mediated by myokines. aBMD and myokine levels were evaluated in relation to the body mass index (BMI) in 179 women. Compared with normal-weight controls (CON; n = 40), women with OB (n = 139) presented higher aBMD, myostatin and follistatin levels and lower irisin levels. Except for irisin levels, all differences between the OB and CON groups were accentuated with increasing BMI. For the whole population (n = 179), weight, BMI, fat mass (FM) and LBM were positively correlated with aBMD at all bone sites, while log irisin were negatively correlated. The proportion of the LBM effect on aBMD was partially mediated (from 14.8% to 29.8%), by log irisin, but not by follistatin or myosin. This study showed that myokine levels were greatly influenced by obesity. However, irisin excepted, myokines do not seem to mediate the effect of LBM on bone tissue.