Does weight loss prognosis depend on genetic make-up?

Genetic variants associated with weight loss and metabolic outcomes after bariatric surgery: A systematic review

The extent to which genetic variations contribute to interindividual differences in weight loss and metabolic outcomes after bariatric surgery is unknown. Identifying genetic variants that impact surgery outcomes may contribute to clinical decision making. This review evaluates current evidence addressing the association of genetic variants with weight loss and changes in metabolic parameters after bariatric surgery. A search was conducted using Medline, Embase, Scopus, Web of Science, and Cochrane Library. Fifty-two eligible studies were identified. Single nucleotide polymorphisms (SNPs) at ADIPOQ (rs226729, rs1501299, rs3774261, and rs17300539) showed a positive association with postoperative change in measures of glucose homeostasis and lipid profiles (n = 4), but not with weight loss after surgery (n = 6). SNPs at FTO (rs11075986, rs16952482, rs8050136, rs9939609, rs9930506, and rs16945088) (n = 10) and MC4R (rs11152213, rs476828, rs2229616, rs9947255, rs17773430, rs5282087, and rs17782313) (n = 9) were inconsistently associated with weight loss and metabolic improvement. Four studies examining the UCP2 SNP rs660339 reported associations with postsurgical weight loss. In summary, there is limited evidence supporting a role for specific genetic variants in surgical outcomes after bariatric surgery. Most studies have adopted a candidate gene approach, limiting the scope for discovery, suggesting that the absence of compelling evidence is not evidence of absence.

The Influence of the Differentiation of Genes Encoding Peroxisome Proliferator-Activated Receptors and Their Coactivators on Nutrient and Energy Metabolism

Genetic components may play an important role in the regulation of nutrient and energy metabolism. In the presence of specific genetic variants, metabolic dysregulation may occur, especially in relation to the processes of digestion, assimilation, and the physiological utilization of nutrients supplied to the body, as well as the regulation of various metabolic pathways and the balance of metabolic changes, which may consequently affect the effectiveness of applied reduction diets and weight loss after training. There are many well-documented studies showing that the presence of certain polymorphic variants in some genes can be associated with specific changes in nutrient and energy metabolism, and consequently, with more or less desirable effects of applied caloric reduction and/or exercise intervention. This systematic review focused on the role of genes encoding peroxisome proliferator-activated receptors (PPARs) and their coactivators in nutrient and energy metabolism. The literature review prepared showed that there is a link between the presence of specific alleles described at different polymorphic points in PPAR genes and various human body characteristics that are crucial for the efficacy of nutritional and/or exercise interventions. Genetic analysis can be a valuable element that complements the work of a dietitian or trainer, allowing for the planning of a personalized diet or training that makes the best use of the innate metabolic characteristics of the person who is the subject of their interventions.

Platform introducing individually tailored variability in nerve stimulations and dietary regimen to prevent weight regain following weight loss in patients with obesity

Prevention of weight regain following successful weight loss is a major challenge in the treatment of obesity, irrespective of the weight reduction method used. The majority of individuals regain the lost weight over time; thus, achieving long-term sustainability in weight loss remains an unresolved issue. A compensatory adaptation to the weight loss methods occurs in several body organs and partly explains the lack of sustainable effect. Variability is inherent in many biological systems, and patterns of variability constitute a body mechanism that is active at several levels, starting from the genes and cellular pathways through to the whole-organ level. This study aimed to describe a platform that introduces individually tailored variability in vagal nerve stimulation and dietary regimen to ensure prolonged and sustainable weight loss and prevent weight regain. The platform is intended to provide a method that can overcome the body's compensatory adaptation mechanisms while ensuring a prolonged beneficial effect.

A circadian rhythm-related MTNR1B genetic variant (rs10830963) modulate body weight change and insulin resistance after 9 months of a high protein/low carbohydrate vs a standard hypocaloric diet

BACKGROUND & AIMS

The risk allele (G) of rs10830963 in the melatonin receptor 1 B (MTNR1B) gene presents an association with biochemical parameters and obesity. We study the effect of this SNP on insulin resistance and weight loss secondary to two hypocaloric diets.

METHODS

270 obese subjects were randomly allocated during 9 months (Diet HP: a high protein/low carbohydrate vs. Diet S: a standard severe hypocaloric diets). Anthropometric parameters, fasting blood glucose, C-reactive protein (CRP), insulin concentration, insulin resistance (HOMA-IR), lipid profile and adipocytokines levels were measured. Genotype of MTNR1B gene polymorphism (rs10830963) was evaluated.

RESULTS

All adiposity parameters, systolic blood pressure and leptin levels decreased in all subjects after both diets. This improvement of adiposity parameters was higher in non-G allele carriers than G allele carriers. After weight loss with Diet HP, (CC vs. CG + GG at 9 months); total cholesterol (delta: -9.9 ± 2.4 mg/dl vs. -4.8 ± 2.2 mg/dl:p < 0.05), LDL-cholesterol (delta: -8.3 ± 1.9 mg/dl vs. -5.1 ± 2.2 mg/dl: p < 0.05), insulin (delta: -4.7 ± 0.8 UI/L vs. -0.9 ± 1.0 UI/L: p < 0.05), triglycerides (delta: -17.7 ± 3.9 mg/dl vs. -6.1 ± 2.8 mg/dl: p < 0.05) and HOMA IR (delta: -0.8 ± 0.2 units vs. -0.2 ± 0.1 units: p < 0.05) improved only in no G allele carriers. After weight loss with Diet S in non G allele carriers, insulin levels (delta (CC vs. CG + GG): -3.4 ± 0.6 UI/L vs. -1.2 ± 0.4 UI/L: p < 0.05), triglycerides (delta: -29.2 ± 3.4 mg/dl vs. -8.2 ± 3.8 mg/dl: p < 0.05), HOMA-IR (delta (CC vs. CG + GG): -1.1 ± 0.2 units vs. -0.1 ± 0.1 units: p < 0.05), total cholesterol (delta: -15.9 ± 7.4 mg/dl vs. -5.8 ± 2.9 mg/dl:ns) and LDL-cholesterol (delta: -13.7 ± 5.9 mg/dl vs. -6.0 ± 2.9 mg/dl: ns) decreased, too.

CONCLUSIONS

our study detected a relationship of rs10830963 variant of MTNR1B gene with adiposity changes, cholesterol changes and insulin resistance modification induced by two different hypocaloric during 9 months.

Pharmacological Treatment for Obesity in Adults: An Umbrella Review

Objective: To synthesize the evidence from systematic reviews of clinical trials investigating the effectiveness of pharmacological therapies approved by the Australian Therapeutic Goods Administration and the US Food and Drug Administration for the management of obesity in adults. Data Sources: A 3-step literature search of the MEDLINE, EMBASE, CINAHL, and PubMed databases was conducted between March and May 2019. The key terms used were obesity, pharmacological therapy, antiobesity agent, antiobesity medication, weight loss, and systematic review. Study Selection and Data Extraction: Systematic reviews that evaluated the effectiveness of pharmacological therapies for the management of obesity in patients with a body mass index of or greater than 25 kg/m². Data Synthesis: Nine systematic reviews involving three pharmacotherapies, liraglutide, orlistat, and naltrexone-bupropion were identified. The results indicate that the pharmacotherapies reduced weight when compared with placebo. Orlistat was effective in significantly reducing fasting blood glucose, HbA1c, total cholesterol, triglycerides, and systolic and diastolic blood pressure. All reviews discussed the presence or risk of gastrointestinal adverse effects including diarrhea, vomiting, and nausea related to orlistat and liraglutide. Relevance to Patient Care and Clinical Practice: This umbrella review compares the efficacy and safety of antiobesity medications for reducing weight and a discussion on their weight loss and metabolic control to guide clinicians when prescribing medications for obesity. Conclusions: All pharmacological therapies included in this review are superior to placebo in reducing weight. Clinicians should consider patient comorbidities and risk of adverse events when recommending medications for weight loss.

Common Variants in Lipid Metabolism-Related Genes Associate with Fat Mass Changes in Response to Dietary Monounsaturated Fatty Acids in Adults with Abdominal Obesity

BACKGROUND

Different fatty acids (FAs) can vary in their obesogenic effect, and genetic makeup can contribute to fat deposition in response to dietary FA composition. However, the antiobesogenic effects of the interactions between dietary MUFAs and genetics have scarcely been tested in intervention studies.

OBJECTIVE

We evaluated the overall (primary outcome) and genetically modulated (secondary outcome) response in body weight and fat mass to different levels of MUFA consumption.

METHODS

In the Canola Oil Multicenter Intervention Trial II, a randomized, crossover, isocaloric, controlled-feeding multicenter trial, 44 men and 71 women with a mean age of 44 y and an increased waist circumference (men ∼108 cm and women ∼102 cm) consumed each of 3 oils for 6 wk, separated by four 12-wk washout periods. Oils included 2 high-MUFA oils-conventional canola and high-oleic canola (<7% SFAs, >65% MUFAs)-and 1 low-MUFA/high-SFA oil blend (40.2% SFAs, 22.0% MUFAs). Body fat was measured using DXA. Five candidate single-nucleotide polymorphisms (SNPs) were genotyped using qualitative PCR. Data were analyzed using a repeated measures mixed model.

RESULTS

No significant differences were observed in adiposity measures following the consumption of either high-MUFA diet compared with the low-MUFA/high-SFA treatment. However, when stratified by genotype, 3 SNPs within lipoprotein lipase (LPL), adiponectin, and apoE genes influenced, separately, fat mass changes in response to treatment (n = 101). Mainly, the LPL rs13702-CC genotype was associated with lower visceral fat (high-MUFA: -216.2 ± 58.6 g; low-MUFA: 17.2 ± 81.1 g; P = 0.017) and android fat mass (high-MUFA: -267.3 ± 76.4 g; low-MUFA: -21.7 ± 102.2 g; P = 0.037) following average consumption of the 2 high-MUFA diets.

CONCLUSIONS

Common variants in LPL, adiponectin, and apoE genes modulated body fat mass response to dietary MUFAs in an isocaloric diet in adults with abdominal obesity. These findings might eventually help in developing personalized dietary recommendations for weight control. The trial was registered at clinicaltrials.gov as NCT02029833 (https://www.clinicaltrials.gov/ct2/show/NCT02029833?cond=NCT02029833&rank=1).

Dietary-fat effect of the rs10830963 polymorphism in MTNR1B on insulin resistance in response to 3 months weight-loss diets

BACKGROUND & AIMS

The risk allele (G) of rs10830963 in the melatonin receptor 1 B (MTNR1B) gene presents an association with obesity. We study the effect of this SNP on cardiovascular risk factors and weight loss secondary to 2hypocaloric diets.

METHODS

361 obese subjects were randomly allocated during 3 months (Diet M - high monounsaturated fat hypocaloric diet vs. Diet P - high polyunsaturated fat hypocaloric diet). Anthropometric parameters, fasting blood glucose, C-reactive protein (CRP), insulin concentration, insulin resistance (HOMA-IR), lipid profile and adipocytokines levels were measured. Genotype of MTNR1B gene polymorphism (rs10830963) was evaluated.

RESULTS

All anthropometric parameters, systolic blood pressure and leptin levels decreased in all subjects after both diets. This improvement of anthropometric parameters was higher in non G allele carriers than G allele carriers. After dietary intervention with Diet M, (CC vs. CG + GG); total cholesterol (delta: -10.4 ± 2.1mg/dl vs. -6.4 ± 1.2mg/dl: P <.05), LDL-cholesterol (delta:-7.1 ± 0.9mg/dl vs. -2.8 ± 0.8mg/dl: P <.05), insulin (delta:-3.0 ± 0.8 UI/L vs. -2.0 ± 1.0 UI/L: P<.05) and HOMA-IR (delta:-3.4 ± 1.0 units vs. -2.9 ± 0.9 units: P<.05) improved in no G allele carriers. After Diet P, in the group of subjects without G allele CC, insulin levels (delta: -2.9 ± 1.0 UI/L vs. -0.6 ± 0.2 UI/L: P <.05) and HOMA-IR (delta (CC vs. CG + GG): -0.8 ± 0.2 units vs. -0.4 ± 0.3 units: P <.05) decreased, too.

CONCLUSIONS

Our study detected a relationship of rs10830963 MTNR1B SNP with body weight loss and insulin resistance modification induced by 2different hypocaloric. Only monounsaturated enriched hypocaloric diet and in no-G allele carriers showed a significant effect on lipoproteins.

How the association between obesity and inflammation may lead to insulin resistance and cancer

BACKGROUND AND OBJECTIVES

Obesity is associated with metabolic dysfunction and over nutrition. Increased body mass index and obesity are strongly amalgamated with changes in the physiological function of adipose tissue, leading to altered secretion of adipocytokines, inflammatory mediators release as well as chronic inflammation and insulin resistance. The purposes of this study were to review the evidence of how obesity and inflammation may lead to insulin resistance and cancer.

SUMMARY

Recent findings suggested that increased level of inflammatory mediators in obesity, plays an introductory and cabalistic role in the development of different types of inflammatory disorders including type 2 diabetes mellitus. Link between elevated body mass index and type 2 diabetes mellitus (T2DM). Several of the factors-such as increased levels of leptin, plasminogen activator inhibitor-1, decreased levels of adiponectin, insulin resistance, chronic inflammation etc. consequently result in carcinogenesis and carcinogenic progression too.

CONCLUSION

This review summarizes how cytokine production in adipose tissue of obese subject creates a chronic inflammatory environment that favors tumor cell motility and invasion to enhance the metastatic potential of tumor cells. High levels of cytokine in the circulation of affected individuals have been associated with a significantly worse outcome. This article also reconnoiters the mechanisms that link obesity to numerous disorders such as inflammation, diabetes, cancers and most specifically combine these processes in a single image. Understanding these mechanisms may assist to understand the consequences of obesity.

DNA methylation signatures in peripheral blood mononuclear cells from a lifestyle intervention for women at midlife: a pilot randomized controlled trial

Physical activity confers many health benefits, but the underlying mechanisms require further exploration. In this pilot randomized controlled trial we tested the association between longitudinal measures of DNA methylation and changes in objective measures, including physical activity, weight loss, and C-reactive protein levels in community-dwelling women aged 55 to 70 years. We assessed DNA methylation from 20 healthy postmenopausal women, who did not have a mobility disability and allocated them to a group-based intervention, Everyday Activity Supports You, or a control group (monthly group-based health-related education sessions). The original randomized controlled trial was 6 months in duration and consisted of nine 2-h sessions that focused on reducing sedentary behaviour for the intervention group, or six 1-h sessions that focused on other topics for the control group. We collected peripheral blood mononuclear cells, both at baseline and 6 months later. Samples were processed using the Illumina 450k Methylation array to quantify DNA methylation at >485 000 CpG sites in the genome. There were no significant associations between DNA methylation and physical activity, but we did observe alterations at epigenetic modifications that correlated with change in percent body weight over a 6-month period at 12 genomic loci, 2 of which were located near the previously reported weight-associated genes RUNX3 and NAMPT. We also generated a potential epigenetic predictor of weight loss using baseline DNA methylation at 5 CpG sites. These exploratory findings suggest a potential biological link between body weight changes and epigenetic processes.

Starch Digestion-Related Amylase Genetic Variant Affects 2-Year Changes in Adiposity in Response to Weight-Loss Diets: The POUNDS Lost Trial

Salivary and pancreatic amylases (encoded by AMY1 and AMY2 genes, respectively) are responsible for digesting starchy foods. AMY1 and AMY2 show copy number variations that affect differences in amylase amount and activity, and AMY1 copies have been associated with adiposity. We investigated whether genetic variants determining amylase gene copies are associated with 2-year changes in adiposity among 692 overweight and obese individuals who were randomly assigned to diets varying in macronutrient content. We found that changes in body weight (BW) and waist circumference (WC) were significantly different according to the AMY1-AMY2 rs11185098 genotype. Individuals carrying the A allele (indicating higher amylase amount and activity) showed a greater reduction in BW and WC at 6, 12, 18, and 24 months than those without the A allele (P < 0.05 for all). The association was stronger for long-term changes compared with short-term changes of these outcomes. The genetic effects on these outcomes did not significantly differ across diet groups. In conclusion, the genetic variant determining starch metabolism influences the response to weight-loss dietary intervention. Overweight and obese individuals carrying the AMY1-AMY2 rs11185098 genotype associated with higher amylase activity may have greater loss of adiposity during low-calorie diet interventions.

Gene-Gene Interplay and Gene-Diet Interactions Involving the MTNR1B rs10830963 Variant with Body Weight Loss

BACKGROUND/AIMS

Investigation of the genetic makeup may facilitate the implementation of more personalized nutritional interventions. The aims were to examine whether the rs10830963 MTNR1B polymorphism affects weight loss in response to a hypocaloric diet and to find potential gene-gene interplays and gene-diet interactions.

METHODS

167 subjects enrolled in a personalized nutritional intervention for weight loss (3-6 weeks) were examined for anthropometric measurements, dietary habits and physical activity at baseline and at the first follow-up visit. Three polymorphisms, which have previously been associated with body weight regulation, rs10830963 (MTNR1B), rs9939609 (FTO) and rs17782313 (MC4R), were analyzed using the Luminex® 100/200™ System.

RESULTS

After adjusting for covariates, females with the rs10830963 CG/GG genotype showed lower weight loss than those with the CC genotype. In the total population, carriers of variant alleles of both FTO and MC4R showed a significant association with MTNR1B and weight loss outcome. Moreover, among women, higher total protein and animal protein intakes were associated with a lower weight loss in G allele carriers of the MTNR1B variant.

CONCLUSIONS

Our data evidenced that rs10830963 MTNR1B polymorphism could be associated with individual differences in weight loss induced by a hypocaloric diet. This association was influenced by FTO and MC4R loci and modified by baseline protein intake.

The Impact of Gender and Protein Intake on the Success of Weight Maintenance and Associated Cardiovascular Risk Benefits, Independent of the Mode of Food Provision: The DiOGenes Randomized Trial

OBJECTIVE

Maintenance of weight loss and associated cardiovascular benefits after following energy-restricted diets is still a challenging field, and thorough investigation is needed. The present research aimed to determine the role of protein and gender in relation to two different intervention models related to food supply, in a weight maintenance trial.

SUBJECTS AND METHODS

The DiOGenes trial was a long-term, multicenter, randomized, dietary intervention study, conducted in eight European countries (Clinical Trials.gov, NCT00390637), focusing on assessing the effectiveness of weight maintenance over 6 months. This secondary analysis intended to evaluate the different benefits for weight maintenance and cardiometabolic markers of two dietary advice delivery models: "shop + instruction intervention" vs "instruction-alone intervention," which were further categorized for gender and macronutrient intake.

RESULTS

The weight maintenance intervention based on different macronutrient intake showed, independently of the advice delivery model, in both sexes that higher protein consumption was more effective for weight stability, showing better results in obese women (low protein: 1.65 kg in males and 0.73 Kg in females vs high protein: 1.45 kg in males and -0.93 Kg in females) . Measurements concerning cardiovascular risk markers from subjects on both structured models produced similar trends in the subsequent follow-up period, with a lower rebound in women for most of the markers analyzed.

CONCLUSION

The reported dietary benefits for weight sustainability should be ascribed to the macronutrient distribution (higher protein diets) rather than to the structured mode of delivery. Higher weight regain in males was noted, as well as a metabolic divergence attributable to the sex, with a better biochemical outcome in women.

Personalized weight loss strategies-the role of macronutrient distribution

A large number of different dietary approaches have been studied in an attempt to achieve healthy, sustainable weight loss among individuals with overweight and obesity. Restriction of energy intake is the primary method of producing a negative energy balance leading to weight loss. However, owing to the different metabolic roles of proteins, carbohydrates and lipids in energy homeostasis, diets of similar overall energy content but with different macronutrient distribution can differentially affect metabolism, appetite and thermogenesis. Evidence increasingly suggests that the fuel values of calories provided by distinct macronutrients should be considered separately, as metabolism of specific molecular components generates differences in energy yield. The causes of variation in individual responses to various diets are currently under debate, and some evidence suggests that differences are associated with specific genotypes. This Review discusses all available systematic reviews and meta-analyses, and summarizes the results of relevant randomized controlled intervention trials assessing the influence of macronutrient composition on weight management. The initial findings of research into personalized nutrition, based on the interactions of macronutrient intake and genetic background and its potential influence on dietary intervention strategies, are also discussed.

Differential proinflammatory and oxidative stress response and vulnerability to metabolic syndrome in habitual high-fat young male consumers putatively predisposed by their genetic background

The current nutritional habits and lifestyles of modern societies favor energy overloads and a diminished physical activity, which may produce serious clinical disturbances and excessive weight gain. In order to investigate the mechanisms by which the environmental factors interact with molecular mechanisms in obesity, a pathway analysis was performed to identify genes differentially expressed in subcutaneous abdominal adipose tissue (SCAAT) from obese compared to lean male (21–35 year-old) subjects living in similar obesogenic conditions: habitual high fat dietary intake and moderate physical activity. Genes involved in inflammation (ALCAM, CTSB, C1S, YKL-40, MIF, SAA2), extracellular matrix remodeling (MMP9, PALLD), angiogenesis (EGFL6, leptin) and oxidative stress (AKR1C3, UCHL1, HSPB7 and NQO1) were upregulated; whereas apoptosis, signal transcription (CITED 2 and NR3C1), cell control and cell cycle-related genes were downregulated. Interestingly, the expression of some of these genes (C1S, SAA2, ALCAM, CTSB, YKL-40 and tenomodulin) was found to be associated with some relevant metabolic syndrome features. The obese group showed a general upregulation in the expression of inflammatory, oxidative stress, extracellular remodeling and angiogenic genes compared to lean subjects, suggesting that a given genetic background in an obesogenic environment could underlie the resistance to gaining weight and obesity-associated manifestations.

Obesity-related gene ADRB2, ADRB3 and GHRL polymorphisms and the response to a weight loss diet intervention in adult women

The individual response to diet may be influenced by gene polymorphisms. This study hypothesized that ADRB2 (Gln27Glu, rs1042714 and Arg16Gly, rs1042713), ADRB3 (Trp64Arg, rs4994) and GHRL (Leu72Met, rs696217) polymorphisms moderate weight loss. The study was a seven weeks dietary weight loss intervention with Brazilian adult obese women (n = 109). The body mass index (BMI) was calculated and polymorphisms in these genes were assessed by real-time PCR assays. Two-way repeated-measures ANOVA (2 × 2) were used to analyze the intervention effect between polymorphisms and BMI over the period and after stratification for age and socioeconomic status (SES). The weight loss intervention resulted in decreased BMI over the seven-week period (p < 0.001), for high and low SES (p < 0.05) and mainly for participants with 30–49 y. The intervention did not result in a statistically significant difference in weight loss between polymorphism carriers and non-carriers, and although, the ADRB2, ADRB3 and GHRL polymorphisms did not moderate weight loss, the Gln27Glu polymorphism carriers showed a lower BMI compared to non-carriers in the low SES (p = 0.018) and the 30–39 y (p = 0.036) groups, suggesting a role for this polymorphism related to BMI control.

Uncoupling protein-2 45-base pair insertion/deletion polymorphism: is there an association with severe obesity and weight loss in morbidly obese subjects?

BACKGROUND

Uncoupling proteins are attractive candidate genes for obesity and type 2 diabetes mellitus. Our aim was to investigate the potential association of the uncoupling protein-2 (UCP2) 45-bp insertion/deletion (ins/del) polymorphism with obesity, as well as the potential effect of this polymorphism on weight loss variability in severely obese subjects.

METHODS

A total of 158 severely obese subjects (94 without and 64 with metabolic syndrome) and 91 age and sex-matched lean controls were recruited. A subgroup of 124 obese patients participated in a 3-month weight loss program. Anthropometric and metabolic variables were measured. Participants were genotyped for the UCP2 ins/del polymorphism.

RESULTS

Allelic frequency differed neither between obese subjects and controls (P=0.56), nor between obese subjects with versus without metabolic syndrome (P=0.58). At 3 months, metabolically healthy subjects carrying the insertion allele had significantly greater reduction in body mass index (P=0.029) and fat-free mass (P=0.013) and a borderline significant improvement in the homeostatic model assessment index (P=0.048).

CONCLUSION

There is no association of the UCP2 ins/del polymorphism with morbid obesity in our population, but this genotype appears to be linked with a favorable response to dietary changes in metabolically healthy obese subjects.

Moderate effects of apple juice consumption on obesity-related markers in obese men: impact of diet-gene interaction on body fat content

PURPOSE

The effect of polyphenol-rich cloudy apple juice (CloA) consumption on plasma parameters related to the obesity phenotype and potential effects of interactions between CloA and allelic variants in obesity candidate genes were assessed in obese men.

METHODS

In this controlled, randomized, and parallel study, n = 68, non-smoking, non-diabetic men with a BMI ≥27 kg/m(2) received 750 mL/day CloA (802.5 mg polyphenols) or 750 mL/day control beverage (CB, isocaloric equivalent to CloA) for 4 weeks. Further, study participants were genotyped for single-nucleotide polymorphisms in PPARγ (rs1801282), UCP3 (rs1800849), IL-6 (rs1800795), FABP2 (rs1799883), INSIG2 (rs7566605), and PGC1 (rs8192678) genes. At the beginning and at the end of intervention plasma lipids, distinct adipokines and cytokines as well as anthropometric parameters were determined.

RESULTS

CloA compared to CB had no significant effect on plasma lipids, plasma adipokine and cytokine levels, BMI, and waist circumference. However, CloA consumption significantly reduced percent body fat compared to CB (∆ % body fat: CloA: -1.0 ± 1.3 vs. CB: -0.2 ± 0.9, p < 0.05). The IL-6-174 G/C polymorphism showed an interaction with body fat reduction induced by CloA. Solely in C/C, but not in G/C or G/G variants, a significant reduction in body fat after 4 weeks of CloA intervention was detectable.

CONCLUSION

The observed diet-gene interaction might be a first indication for the impact of individual genetic background on CloA-mediated bioactivity on obesity-associated comorbidities.

Allelic variants of melanocortin 3 receptor gene (MC3R) and weight loss in obesity: a randomised trial of hypo-energetic high- versus low-fat diets

Introduction

The melanocortin system plays an important role in energy homeostasis. Mice genetically deficient in the melanocortin-3 receptor gene have a normal body weight with increased body fat, mild hypophagia compared to wild-type mice. In humans, Thr6Lys and Val81Ile variants of the melanocortin-3 receptor gene (MC3R) have been associated with childhood obesity, higher BMI Z-score and elevated body fat percentage compared to non-carriers. The aim of this study is to assess the association in adults between allelic variants of MC3R with weight loss induced by energy-restricted diets.

Subjects and Methods

This research is based on the NUGENOB study, a trial conducted to assess weight loss during a 10-week dietary intervention involving two different hypo-energetic (high-fat and low-fat) diets. A total of 760 obese patients were genotyped for 10 single nucleotide polymorphisms covering the single exon of MC3R gene and its flanking regions, including the missense variants Thr6Lys and Val81Ile. Linear mixed models and haplotype-based analysis were carried out to assess the potential association between genetic polymorphisms and differential weight loss, fat mass loss, waist change and resting energy expenditure changes.

Results

No differences in drop-out rate were found by MC3R genotypes. The rs6014646 polymorphism was significantly associated with weight loss using co-dominant (p = 0.04) and dominant models (p = 0.03). These p-values were not statistically significant after strict control for multiple testing. Haplotype-based multivariate analysis using permutations showed that rs3827103–rs1543873 (p = 0.06), rs6014646–rs6024730 (p = 0.05) and rs3746619–rs3827103 (p = 0.10) displayed near-statistical significant results in relation to weight loss. No other significant associations or gene*diet interactions were detected for weight loss, fat mass loss, waist change and resting energy expenditure changes.

Conclusion

The study provided overall sufficient evidence to support that there is no major effect of genetic variants of MC3R and differential weight loss after a 10-week dietary intervention with hypo-energetic diets in obese Europeans.

Regulation by chronic-mild stress of glucocorticoids, monocyte chemoattractant protein-1 and adiposity in rats fed on a high-fat diet

Stress has been reported as a widespread problem and several studies have linked obesity and inflammation-related diseases. Moreover, the combination of suffering from chronic stress and high energy intake might be related to the onset of some metabolic diseases. To study the possible relationships between stress, inflammatory status and obesity, a chronic-mild stress (CMS) paradigm with a high-fat dietary intake model (Cafeteria diet) was implemented on male Wistar rats for 11 weeks. Stress and dietary intake effects on animal adiposity, serum biochemical as well as glucocorticoids and inflammation markers were all analyzed. As expected, consuming a high-fat diet increased body weight, adiposity and insulin resistance in non-stressed animals. A decrease of total white adipose tissue (WAT) and an increase of fecal glucocorticoids, as well as angiotensinogen, and monocyte chemoattractant protein-1 (MCP-1) expression level in retroperitoneal WAT were found only on control-stressed rats. Regarding the serum MCP-1, a decrease was observed on animals under CMS while being fed Cafeteria diet. Furthermore, 11β-hydroxysteroid dehydrogenase activity, a glucocorticoid and obesity biomarker in the liver, was influenced by high-fat diet intake but not by stress. Finally, statistical analysis showed a strong relation between MCP-1 expression levels in retroperitoneal WAT, fecal corticosterone and total WAT. This trial proved that CMS induced a glucocorticoid-mediated response, which was reduced by the intake of a Cafeteria diet. These findings suggest that a high-fat diet could protect against a stress condition and revealed a different behavior to a stressful environment depending on the nutritional status.

Predictors of weight loss and maintenance in patients treated with antiobesity drugs

BACKGROUND

The prevalence of obesity and related diseases has increased enormously in the last few decades, becoming a very important medical and social issue. Because of the increasing number of people who need weight loss therapies and the high costs associated with these, the search for reliable predictors of success for weight loss and weight maintenance treatments has become a priority.

OBJECTIVE

A literature review was undertaken to identify possible predictors of outcome of weight loss and weight maintenance in patients treated with antiobesity drugs.

RESULTS

For the majority of variables, published data are not sufficient to define their role on final outcomes. Among all considered factors, only early response to treatment appeared to be a reliable positive predictor, and diabetes a negative predictor of weight loss and maintenance.

CONCLUSION

To date, no definitive results have been obtained. Due to the great benefits of reliable predictors of outcome associated to currently available antiobesity drugs and those under development, identifying these predictors has to be supported and encouraged.

Role of obesity-associated dysfunctional adipose tissue in cancer: a molecular nutrition approach

Obesity is a complex disease caused by the interaction of a myriad of genetic, dietary, lifestyle and environmental factors, which favors a chronic positive energy balance, leading to increased body fat mass. There is emerging evidence of a strong association between obesity and an increased risk of cancer. However, the mechanisms linking both diseases are not fully understood. Here, we analyze the current knowledge about the potential contribution that expanding adipose tissue in obesity could make to the development of cancer via dysregulated secretion of pro-inflammatory cytokines, chemokines and adipokines such as TNF-α, IL-6, leptin, adiponectin, visfatin and PAI-1. Dietary factors play an important role in the risk of suffering obesity and cancer. The identification of bioactive dietary factors or substances that affect some of the components of energy balance to prevent/reduce weight gain as well as cancer is a promising avenue of research. This article reviews the beneficial effects of some bioactive food molecules (n-3 PUFA, CLA, resveratrol and lipoic acid) in energy metabolism and cancer, focusing on the molecular mechanisms involved, which may provide new therapeutic targets in obesity and cancer.

Genetic variants influencing effectiveness of weight loss strategies

Body weight excess has an increasingly high prevalence in the world. Obesity is a complex disease of multifactorial origin with a polygenic condition affected by environmental factors. Weight loss is a primary strategy to treat obesity and its morbidities. Weight changes through life depend on the interaction of environmental, behavioral and genetic factors. Interindividual variation of weight loss in response to different types of interventions (behavioral, caloric restriction, exercise, drug or surgery) has been observed. In this article, currently available data on the role of candidate gene polymorphisms in weight loss are reviewed. Even though control of weight loss by genotype was described in twin and family studies, it is premature to recommend use of genotyping in the design of therapeutic diets or drug treatment. Future studies will have to be large in order to assess the effects of multiple polymorphisms, and will have to control factors other than diet.

PPARG genotype accounts for part of individual variation in body weight reduction in response to calorie restriction

Several studies indicate that expression of the peroxisome proliferator-activated receptor gamma (PPARG) gene is influenced by calorie restriction. The aim of this study was to investigate whether PPARG gene variations are associated with weight reduction and changes in coronary heart disease (CHD) risk factors in response to a 14-week calorie restriction. In total, 95 middle-aged, Japanese women (BMI>or=25 kg/m2) enrolled as subjects for 14 weeks and attended weekly dietary lectures instructing them on how to consume a nutritionally balanced diet of 1,200 kcal/day. Eight single-nucleotide polymorphisms (SNPs) in the PPARG gene (rs1801282 (Pro/Ala), rs2292101, rs2959272, rs1386835, rs709158, rs1175540, rs1175544, and rs1797912) were analyzed. Body weight decreased significantly (-7.7+/-3.1 kg; -11.3+/-4.4%) during the intervention. Six PPARG SNPs (rs2959272, rs1386835, rs709158, rs1175540, rs1175544, and rs1797912) were significantly associated with the weight reduction, with rs1175544 having the strongest association (P=0.004). No differences across the rs1175544 genotypes were observed in any of the blood analyses or in blood pressure. In a multiple regression analysis, the rs1175544 genotypes accounted for 7% of the total weight reduction variance. These data suggest that one SNP of the PPARG genotype accounted for a significant portion of the total body weight reduction variance in response to a short-term intervention consisting of calorie restriction; however, no relationship was found between these SNPs and the changes in CHD risk factors which accompanied weight loss.

A hypocaloric diet enriched in legumes specifically mitigates lipid peroxidation in obese subjects

Legume intake could specifically protect against lipid peroxidation in addition to the effects associated to weight loss when included in hypocaloric diets. Thus, 30 obese subjects (age: 36 +/- 8 years and BMI: 32.0 +/- 5.3 kg/m(2)) were nutritionally treated by a 8-week energy restriction ( - 30% energy expenditure) with a legume enriched diet (4 days/week servings, [image omitted] ) or without legumes (control diet (CD), [image omitted] ). Body weight, circulating cholesterol, oxidized LDL (ox-LDL), malondialdehyde (MDA) and urinary 8-isoprostane F(2alpha) (8-iso-PGF(2alpha)) were measured at baseline and at endpoint. After the nutritional intervention, all obese subjects lost weight, specially those individuals who followed the legumes-enriched diet as compared to the CD ( - 7.7 +/- 3 vs. - 5.3 +/- 2.7%; p = 0.023), which was accompanied by marked decreases in total cholesterol levels (p < 0.001) and statistically significant diet-related reductions on plasma ox-LDL, plasma MDA and urinary 8-iso-PGF(2alpha) output. Therefore, a balanced diet with moderate caloric restriction including 4 day/week legume servings empowered the oxidative stress improvement related to weight loss through a reduction in lipid peroxidation as compared to a control hypocaloric diet.

TNF-alpha promoter methylation as a predictive biomarker for weight-loss response

Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine which is commonly elevated in obese subjects and whose promoter is susceptible to be regulated by cytosine methylation. The aim of this research was to analyze whether epigenetic regulation of human TNF-alpha promoter by cytosine methylation could be involved in the predisposition to lose body weight after following a balanced hypocaloric diet. Twenty-four patients (12 women/12 men) with excessive body weight-for-height (BMI: 30.5+/-0.32 kg/m2; age: 34+/-4 years old) followed an 8-week energy-restricted diet. Blood mononuclear cell DNA, isolated before the nutritional intervention, was treated with bisulfite and a region of TNF-alpha gene promoter (from -360 to +50 bp) was sequenced. Obese men with successful weight loss (>or=5% of initial body weight) showed lower levels of total TNF-alpha promoter methylation (r=0.74; P=0.021), especially in the positions -170 bp (r=0.75, P=0.005) and -120 bp (r=0.70, P=0.011). Baseline TNF-alpha circulating levels were positively associated with total promoter methylation (r=0.84, P=0.005) and methylation at position -245 bp (r=0.75, P=0.020). TNF-alpha promoter methylation could be a good inflammation marker predicting the hypocaloric diet-induced weight-loss, and constitutes a first step toward personalized nutrition based on epigenetic criteria.

Motivation, readiness to change, and weight loss following adjustable gastric band surgery

High levels of readiness to change (RTC) are considered critical to the long-term success of weight management programs including bariatric surgery. However, there are no data to support this assertion. We hypothesize that RTC level will not influence weight outcomes following surgery. In 227 consecutive patients undergoing adjustable gastric banding surgery, we recorded reasons for seeking surgery, and RTC measured with the University of Rhode Island Change Assessment. Scores were blinded until study completion. The primary outcome measure was percentage of excess BMI loss at 2 years (%EBMIL-2); others included compliance and surgical complications. Of 227 subjects, 204 (90%) had weight measurement at 2 years. There was no significant correlation between RTC score and %EBMIL-2 (r = 0.047, P = 0.5). Using the median split for RTC score the lowest 102 subjects mean %EBMIL-2 was 52.9 +/- 26.9% and the highest 52.2 +/- 28.3%, P = 0.869. There was no weight loss difference between highest and lowest quartiles, or a nonlinear relationship between weight loss and RTC score. There was no significant relationship between RCT score and compliance, or likelihood of complications. Those motivated by appearance were more likely to be younger women who lost more weight at 2 years. Poor attendance at follow-up visits was associated with less weight loss, especially in men. Measures of RTC did not predict weight loss, compliance, or surgical complications. Caution is advised when using assessments of RTC to predict outcomes of bariatric surgery.

Role of adipogenic and thermogenic genes in susceptibility or resistance to develop diet-induced obesity in rats

The aim of the present work was to assess whether changes in adipose tissue gene expression related with adipogenesis and/or thermogenesis could be involved in the mechanism conferring susceptibility or resistance to develop obesity in high-fat fed outbreed rats. For this purpose, male Wistar rats were fed with standard laboratory diet (control group) or high fat diet. After 15 days, two groups of rats with significant differences on body weight gain in response to the high fat diet were characterized and identified as diet-induced obesity (DIO) and diet resistant (DR) rats. A significant increase in visceral white adipose tissue (WAT) PPARgamma and aP2 (p < 0.05) mRNA levels associated to a decrease in RARgamma expression (p < 0.05) was observed in DIO rats, suggesting an increase of adipogenesis. Furthermore, our data showed a marked increase in brown adipose tissue (BAT) of UCP1 mRNA in DIO animals (p < 0.01) (without affecting PGC-1alpha gene expression), whereas no changes were found in WAT UCP2 gene expression. All these data suggest that the variations found in the expression pattern of PPARgamma, aP2 and RARgamma by high-fat diet could be involved, at least in part, in the differences in body weight gain and adiposity observed between DR and DIO animals. The compensatory adaptations through the increase in energy expenditure by changes on the expression levels of UCP1 seem not to be enough to avoid the obesity onset in the DIO group.

Impact of body weight, diet and lifestyle on nonalcoholic fatty liver disease

Nonalcoholic steatohepatitis is part of the broader spectrum of nonalcoholic fatty liver disease, strongly associated with insulin resistance, obesity and the metabolic syndrome. Its increasing prevalence appears to be closely related to the increased frequency of overweight or obesity; which is associated with changes in dietary habits, including an increased consumption of hypercaloric food and saturated fat, often concurrent with decreased activity and energy expenditure. Weight loss through dieting and increasing energy expenditure through the practice of regular exercise has been shown to be effective in improving nonalcoholic fatty liver disease/nonalcoholic steatohepatitis, and is considered the mainstay of treatment. The effectiveness of these lifestyle interventions seems to rely chiefly on an improvement in insulin sensitivity. At present, disease management using a multidisciplinary team is probably pivotal for patient-centered quality of care.

Evolutionary origins of obesity

Although it appeared relatively suddenly, the current obesity epidemic - largely manifest in industrialized societies but now spreading to the rest of the world - is the result of interaction between human biology and human culture over the long period of human evolution. As mammals and primates, humans have the capacity to store body fat when opportunities to consume excess energy arise. But during the millions of years of human evolution such opportunities were rare and transient. More commonly ancestral hominins and modern humans were confronted with food scarcity and had to engage in high levels of physical activity. In tandem with encephalization, humans evolved elaborate and complex genetic and physiological systems to protect against starvation and defend stored body fat. They also devised technological aids for increasing energy consumption and reducing physical effort. In the last century, industrialization provided access to great quantities of mass-produced, high-calorie foods and many labour-saving and transportation devices, virtually abolishing starvation and heavy manual work. In the modern obesogenic environment, individuals possessing the appropriate combination of ancestral energy-conserving genes are at greater risk for overweight and obesity and associated chronic diseases.

Physiogenomic comparison of human fat loss in response to diets restrictive of carbohydrate or fat

Background

Genetic factors that predict responses to diet may ultimately be used to individualize dietary recommendations. We used physiogenomics to explore associations among polymorphisms in candidate genes and changes in relative body fat (Δ%BF) to low fat and low carbohydrate diets.

Methods

We assessed Δ%BF using dual energy X-ray absorptiometry (DXA) in 93 healthy adults who consumed a low carbohydrate diet (carbohydrate ~12% total energy) (LC diet) and in 70, a low fat diet (fat ~25% total energy) (LF diet). Fifty-three single nucleotide polymorphisms (SNPs) selected from 28 candidate genes involved in food intake, energy homeostasis, and adipocyte regulation were ranked according to probability of association with the change in %BF using multiple linear regression.

Results

Dieting reduced %BF by 3.0 ± 2.6% (absolute units) for LC and 1.9 ± 1.6% for LF (p < 0.01). SNPs in nine genes were significantly associated with Δ%BF, with four significant after correction for multiple statistical testing: rs322695 near the retinoic acid receptor beta (RARB) (p < 0.005), rs2838549 in the hepatic phosphofructokinase (PFKL), and rs3100722 in the histamine N-methyl transferase (HNMT) genes (both p < 0.041) due to LF; and the rs5950584 SNP in the angiotensin receptor Type II (AGTR2) gene due to LC (p < 0.021).

Conclusion

Fat loss under LC and LF diet regimes appears to have distinct mechanisms, with PFKL and HNMT and RARB involved in fat restriction; and AGTR2 involved in carbohydrate restriction. These discoveries could provide clues to important physiologic mechanisms underlying the Δ%BF to low carbohydrate and low fat diets.

Treatment modalities of obesity: what fits whom?

The prevalence of obesity is increasing in both developed and developing countries, with rates reaching approximately 10-35% among adults in the Euro-American region. Obesity is associated with increased risks of cardiovascular diseases, type 2 diabetes, arthritis, and some type of cancers. Obesity significantly affects the quality of life and reduces the average life expectancy. The effective treatment of obesity should address both the medical and the social burden of this disease. Obesity needs to be treated within the health care system as any other complex disease, with empathy and without prejudice. Both health care providers and patients should know that the obesity treatment is a lifelong task. They should also set realistic goals before starting the treatment, whereas keeping in mind that even a modest weight loss of 5-15% significantly reduces obesity-related health risks. Essential treatment of obesity includes low-calorie low-fat diets, increased physical activity, and strategies contributing to the modification of lifestyle. Anti-obesity drugs facilitate weight loss and contribute to further amelioration of obesity-related health risks. A short-term weight loss, up to 6 months, is usually achieved easily. However, the long-term weight management is often associated with a lack of compliance, failures, and a high dropout rate. Regular physical activity, cognitive behavioral modification of lifestyle, and administration of anti-obesity drugs improve weight loss maintenance. Bariatric surgery is an effective strategy to treat severely obese patients. Bariatric surgery leads to a substantial improvement of comorbidities as well as to a reduction in overall mortality by 25-50% during the long-term follow-up. Obesity treatment should be individually tailored and the following factors should be taken into account: sex, the degree of obesity, individual health risks, psychobehavioral and metabolic characteristics, and the outcome of previous weight loss attempts. In the future, an evaluation of hormonal and genetic determinants of weight loss could also contribute to a better choice of individual therapy for a particular obese patient. A multilevel obesity management network of mutually collaborating facilities should be established to provide individually tailored treatment. Centers of excellence in obesity management represented by multidisciplinary teams should provide comprehensive programs for the treatment of obesity derived from evidence-based medicine.

Adipose gene expression prior to weight loss can differentiate and weakly predict dietary responders

BACKGROUND

The ability to identify obese individuals who will successfully lose weight in response to dietary intervention will revolutionize disease management. Therefore, we asked whether it is possible to identify subjects who will lose weight during dietary intervention using only a single gene expression snapshot.

METHODOLOGY/PRINCIPAL FINDINGS

The present study involved 54 female subjects from the Nutrient-Gene Interactions in Human Obesity-Implications for Dietary Guidelines (NUGENOB) trial to determine whether subcutaneous adipose tissue gene expression could be used to predict weight loss prior to the 10-week consumption of a low-fat hypocaloric diet. Using several statistical tests revealed that the gene expression profiles of responders (8-12 kgs weight loss) could always be differentiated from non-responders (<4 kgs weight loss). We also assessed whether this differentiation was sufficient for prediction. Using a bottom-up (i.e. black-box) approach, standard class prediction algorithms were able to predict dietary responders with up to 61.1%+/-8.1% accuracy. Using a top-down approach (i.e. using differentially expressed genes to build a classifier) improved prediction accuracy to 80.9%+/-2.2%.

CONCLUSION

Adipose gene expression profiling prior to the consumption of a low-fat diet is able to differentiate responders from non-responders as well as serve as a weak predictor of subjects destined to lose weight. While the degree of prediction accuracy currently achieved with a gene expression snapshot is perhaps insufficient for clinical use, this work reveals that the comprehensive molecular signature of adipose tissue paves the way for the future of personalized nutrition.

Genetics of obesity

Objective

The aim was to review and update advances in genetics of obesity.

Design

Analysis and interpretation of recent investigations about regulating the energy balance as well as about gene-nutrient interactions and current nutrigenomic research methods.

Background and main statements

Obesity results from a long-term positive energy balance. However, its rising prevalence in developed and developing societies must reflect lifestyle changes, since genetic susceptibility remains stable over many generations. Like most complex diseases, obesity derives from a failure of adequate homoeostasis within the physiological system controlling body weight. The identification of genes that are involved in syndromic, monogenic and polygenic obesity has seriously improved our knowledge of body weight regulation. This disorder may arise from a deregulation at the genetic level (e.g. gene transcription or altered protein function) or environmental exposure (e.g. diet, physical activity, etc.).

Conclusions

In practice, obesity involves the interaction between genetic and environmental factors.

Baseline serum folate level may be a predictive factor of weight loss in a morbid-obesity-management programme

Prompt identification of responders to non-surgical therapy is of utmost importance in attempting medical treatment in patients with clinically severe obesity before indication of bariatric surgery. The objectives of the present study were to assess the outcome at 1 year of morbidly obese patients undergoing a weight-loss medical programme and to detect baseline predictors of a loss ≥10 % of initial weight at the end of the follow-up. A longitudinal, prospective study of a cohort of morbidly obese patients (n 182; females 78 %; age 40·5 (sd 11·5) years; BMI 45·4 (sd 6·0) kg/m2) enrolled in a 1-year obesity-management programme based on lifestyle changes and pharmacological therapy. Significant laboratory and clinical variables were included in a binary logistic regression model in order to identify baseline independent factors for the prediction of a successful outcome in the programme. At 12 months of follow-up, twenty-one subjects (11·5 % of the initial cohort) had lost ≥10 % of baseline weight. A high serum folic acid level was the only independent predictor of weight loss at 1 year. A rise of 1 ng/ml in serum folate increased the chance of success by 28 % (adjusted odds ratio 1·28; 95 % CI 1·04, 1·58). We concluded that a medical-management programme of morbid obesity obtained limited results at 1 year, in agreement with other intervention studies. Serum folate may be useful as a pre-treatment predictor of response to a medical-management programme in patients with morbid obesity. Patients with low basal serum folate levels probably should be urged to change unhealthy eating patterns.

Effect of genotype on success of lifestyle intervention in subjects at risk for type 2 diabetes

Lifestyle intervention programs including increased physical activity and healthy nutrition have been proven to delay the onset of type 2 diabetes. This is achieved mainly by reducing body weight and improving insulin sensitivity. However, response to lifestyle or dietary interventions does differ between individuals, and the genetic or environmental factors that may account for these differences are not yet precisely characterized. Identification of these factors would be desirable in order to provide an individually tailored preventive strategy for patients at risk of developing diabetes. This review summarizes the so far known genetic variations, which determine responders and nonresponders to a lifestyle intervention. In addition, general methodological approaches to study gene-lifestyle interactions are described.

Murine weight loss exhibits significant genetic variation during dietary restriction

We present genetic analyses of murine weight loss during dietary restriction (DR) for females eating 60% ad libitum (AL). We examined 5 cohorts across 81 different strains (22 strains tested twice) that included the LXS and LSXSS recombinant inbred strains, the LXS parental strains ILS and ISS, and the classical inbreds 129S6, A, BALB/c, C57BL/6, C3H, and DBA. Weight loss exhibited highly significant genetic variation, with DR body weights ranging from ∼60 to ∼85% of AL body weight. This variation was not explained by the strain differences in absolute food intake, feces calorie content, motor activity, or AL body fat. Heritability was 40–50%, and several provisional quantitative trait loci were mapped. This variation can be used to test whether weight loss correlates with the health benefits of DR, independently of the reduction in calories. The genetic variation also implies the existence of genes that would be novel therapeutic targets, distinct from genes affecting AL body weight or body fat, for enhancing (or mitigating) weight loss during food restriction.

Differences in short-term metabolic responses to a lipid load in lean (resistant) vs obese (susceptible) young male subjects with habitual high-fat consumption

OBJECTIVE

To determine the role of macronutrients oxidation ability in the postprandial response to a high lipid load in the mechanisms conferring resistance or susceptibility to obesity.

SUBJECTS AND DESIGN

Nine lean and nine obese young male subjects with habitual similar high-fat intake (>40 % of energy) and comparable physical activity were selected and categorized as 'resistant', those who remained lean (body mass index (BMI) <25 kg/m2), and 'susceptible', those who were obese (BMI>30 kg/m2). Fasting blood samples were taken for the evaluation of blood metabolic and hormonal variables. Resting metabolic rate (RMR) and substrates oxidation were measured by indirect calorimetry, in the fasting state and every 30 min for 3 h after a rich lipid meal (fat 94.7%) supplied to cover the 50% of the volunteers energy requirements. The study was performed at the Metabolic Unit of the University of Navarra.

RESULTS

Fasting RMR and lipid oxidation were higher in obese-susceptible subjects. However, similar values were found in both groups after adjustment for fat mass and free fat mass. The cumulative postprandial fat oxidation was also similar in both groups (despite having different tissue metabolic activity), whereas cumulative carbohydrate oxidation was lower in the obese-susceptible group. The thermic effect of food (% of dietary induced thermogenesis) was lower (P<0.05) in the susceptible-obese subjects. The energy and fat balance were more positive in the obesity-susceptible individuals after the high fat load, who also showed higher fasting homeostatic model assessment index, low-density lipoprotein-cholesterol and triacylglyceride levels, hyperleptinemia and hypoadiponectinemia.

CONCLUSION

Lean-resistant individuals came closer to achieving fat balance than obese-susceptible subjects. These metabolic and hormonal differences are probably genetically determined.

Differential expression of aquaporin 7 in adipose tissue of lean and obese high fat consumers

Aquaporin 7 (AQP7) is an aquaglyceroprotein responsible for the secretion and uptake of glycerol from the adipocyte. The modulation of the expression of this membrane transport protein might play an important role in the susceptibility to the development of obesity. The aim of the present study was to compare the AQP7 gene expression in subcutaneous abdominal fat in lean vs. obese high fat intakers with a similar daily physical activity pattern. Twelve young men, 6 lean (BMI=23.2+/-0.4kg/m(2)) and 6 obese (35.0+/-1.1kg/m(2)) with a similar habitual dietary intake of fat (45.5+/-2.5 vs. 43.5+/-1.7% daily energy from fat for lean and obese, respectively) and physical activity (16.0+/-5.7 vs. 17.2+/-5.1 METsh/week for lean and obese, respectively), were recruited. Subcutaneous abdominal fat biopsies were obtained and total RNA was extracted and purified. Pools of RNA from lean and obese individuals were probed into Affymetrix GeneChip Human U133A. The microarray analysis revealed that AQP7 gene was down-regulated in obese compared to lean subjects. The results of the microarray analysis were confirmed by real-time PCR studies. In summary, our data show that the AQP7 gene is differentially expressed in adipose tissue of lean and obese individuals. The down-regulation of the AQP7 gene could be implicated in the susceptibility to obesity by reducing glycerol release and promoting the accumulation of lipids in the adipose tissue.