Circulating ACE is a predictor of weight loss maintenance not only in overweight and obese women, but also in men

Yoyo Dieting, Post-Obesity Weight Loss, and Their Relationship with Gut Health

Excessive body weight is associated with many chronic metabolic diseases and weight loss, so far, remains the gold standard treatment. However, despite tremendous efforts exploring optimal treatments for obesity, many individuals find losing weight and maintaining a healthy body weight difficult. Weight loss is often not sustainable resulting in weight regain and subsequent efforts to lose weight. This cyclic pattern of weight loss and regain is termed "yoyo dieting" and predisposes individuals to obesity and metabolic comorbidities. How yoyo dieting might worsen obesity complications during the weight recurrence phase remains unclear. In particular, there is limited data on the role of the gut microbiome in yoyo dieting. Gut health distress, especially gut inflammation and microbiome perturbation, is strongly associated with metabolic dysfunction and disturbance of energy homeostasis in obesity. In this review, we summarise current evidence of the crosstalk between the gastrointestinal system and energy balance, and the effects of yoyo dieting on gut inflammation and gut microbiota reshaping. Finally, we focus on the potential effects of post-dieting weight loss in improving gut health and identify current knowledge gaps within the field, including gut-derived peptide hormones and their potential suitability as targets to combat weight regain, and how yoyo dieting and associated changes in the microbiome affect the gut barrier and the enteric nervous system, which largely remain to be determined.

The Impact of Yoyo Dieting and Resistant Starch on Weight Loss and Gut Microbiome in C57Bl/6 Mice

Cyclic weight loss and subsequent regain after dieting and non-dieting periods, a phenomenon termed yoyo dieting, places individuals at greater risk of metabolic complications and alters gut microbiome composition. Resistant starch (RS) improves gut health and systemic metabolism. This study aimed to investigate the effect of yoyo dieting and RS on the metabolism and gut microbiome. C57BL/6 mice were assigned to 6 diets for 20 weeks, including control, high fat (HF), yoyo (alternating HF and control diets every 5 weeks), control with RS, HF with RS, and yoyo with RS. Metabolic outcomes and microbiota profiling using 16S rRNA sequencing were examined. Yoyo dieting resulted in short-term weight loss, which led to improved liver health and insulin tolerance but also a greater rate of weight gain compared to continuous HF feeding, as well as a different microbiota profile that was in an intermediate configuration between the control and HF states. Mice fed HF and yoyo diets supplemented with RS gained less weight than those fed without RS. RS supplementation in yoyo mice appeared to shift the gut microbiota composition closer to the control state. In conclusion, yoyo dieting leads to obesity relapse, and increased RS intake reduces weight gain and might help prevent rapid weight regain via gut microbiome restoration.

Normobaric hypoxia shows enhanced FOXO1 signaling in obese mouse gastrocnemius muscle linked to metabolism and muscle structure and neuromuscular innervation

Skeletal muscle relies on mitochondria for sustainable ATP production, which may be impacted by reduced oxygen availability (hypoxia). Compared with long-term hypoxia, the mechanistic in vivo response to acute hypoxia remains elusive. Therefore, we aimed to provide an integrated description of the Musculus gastrocnemius response to acute hypoxia. Fasted male C57BL/6JOlaHsd mice, fed a 40en% fat diet for six weeks, were exposed to 12% O2 normobaric hypoxia or normoxia (20.9% O2) for six hours (n = 12 per group). Whole-body energy metabolism and the transcriptome response of the M. gastrocnemius were analyzed and confirmed by acylcarnitine determination and Q-PCR. At the whole-body level, six hours of hypoxia reduced energy expenditure, increased blood glucose and tended to decreased the respiratory exchange ratio (RER). Whole-genome transcriptome analysis revealed upregulation of forkhead box-O (FOXO) signalling, including an increased expression of tribbles pseudokinase 3 (Trib3). Trib3 positively correlated with blood glucose levels. Upregulated carnitine palmitoyltransferase 1A negatively correlated with the RER, but the significantly increased in tissue C14-1, C16-0 and C18-1 acylcarnitines supported that β-oxidation was not regulated. The hypoxia-induced FOXO activation could also be connected to altered gene expression related to fiber-type switching, extracellular matrix remodeling, muscle differentiation and neuromuscular junction denervation. Our results suggest that a six-hour exposure of obese mice to 12% O2 normobaric hypoxia impacts M. gastrocnemius via FOXO1, initiating alterations that may contribute to muscle remodeling of which denervation is novel and warrants further investigation. The findings support an early role of hypoxia in tissue alterations in hypoxia-associated conditions such as aging and obesity.

Differential mechanisms affecting weight loss and weight loss maintenance

In most lifestyle, pharmacological and surgical interventions, weight loss occurs over an approximately 6- to 9-month period and is followed by a weight plateau and then weight regain. Overall, only about 15% of individuals can sustain a 10% or greater non-surgical, non-pharmacological, weight loss. A key question is the degree to which the genotypes, phenotypes and environmental correlates of success in weight loss and weight loss maintenance are continuous or dichotomous. This Perspective is a comparison of the interactions of weight loss and maintenance with genetic, behavioural, physiological and environmental homeostatic systems and a discussion of the implications of these findings for research in, and treatment of, obesity. Data suggest that weight loss and weight loss maintenance are physiologically and psychologically different in many ways. Consequently, individuals may require different interventions designed for temporarily sustaining a negative energy balance during weight loss versus permanently maintaining energy balance after weight loss.

Urinary ACE Phenotyping as a Research and Diagnostic Tool: Identification of Sex-Dependent ACE Immunoreactivity

BACKGROUND

Angiotensin-converting enzyme (ACE) is highly expressed in renal proximal tubules, but ACE activity/levels in the urine are at least 100-fold lower than in the blood. Decreased proximal tubular ACE has been associated with renal tubular damage in both animal models and clinical studies. Because ACE is shed into urine primarily from proximal tubule epithelial cells, its urinary ACE measurement may be useful as an index of tubular damage.

OBJECTIVE AND METHODOLOGY

We applied our novel approach-ACE phenotyping-to characterize urinary ACE in volunteer subjects. ACE phenotyping includes (1) determination of ACE activity using two substrates (ZPHL and HHL); (2) calculation of the ratio of hydrolysis of the two substrates (ZPHL/HHL ratio); (3) quantification of ACE immunoreactive protein levels; and (4) fine mapping of local ACE conformation with mAbs to ACE.

PRINCIPAL FINDINGS

In normal volunteers, urinary ACE activity was 140-fold less than in corresponding plasma/serum samples and did not differ between males and females. However, urinary ACE immunoreactivity (normalized binding of 25 mAbs to different epitopes) was strongly sex-dependent for the several mAbs tested, an observation likely explained by differences in tissue ACE glycosylation/sialylation between males and females. Urinary ACE phenotyping also allowed the identification of ACE outliers. In addition, daily variability of urinary ACE has potential utility as a feedback marker for dieting individuals pursuing weight loss.

CONCLUSIONS/SIGNIFICANCE

Urinary ACE phenotyping is a promising new approach with potential clinical significance to advance precision medicine screening techniques.

Plasma Levels of Triglycerides and IL-6 Are Associated With Weight Regain and Fat Mass Expansion

CONTEXT

Long-term weight loss (WL) maintenance is the biggest challenge for overweight and obesity because of the almost unavoidable phenomenon of partial or even total weight regain (WR) after WL.

OBJECTIVE

In the present study we investigated the relations of (the changes of) adipocyte size and other risk biomarkers with WR during the follow-up of the Yoyo dietary intervention.

METHODS

In this randomized controlled study, 48 overweight/obese participants underwent a very-low-calorie diet to lose weight, followed by a weight-stable period of 4 weeks and a follow-up period of 9 months. Anthropometric measurements, adipocyte volume of abdominal subcutaneous adipose tissue, and plasma metabolic parameters (free fatty acids [FFAs], triglycerides [TGs], total cholesterol, glucose, insulin, homeostasis model assessment of insulin resistance [HOMA-IR], interleukin 6 [IL-6], angiotensin-converting enzyme [ACE] activity, retinol binding protein 4 [RBP4]) at the beginning and the end of follow-up were analyzed.

RESULTS

Our results show that changes of TGs, IL-6, HOMA-IR, and ACE are significantly positively correlated with WR. Multiple linear regression analysis shows that only TG and IL-6 changes remained significantly correlated with WR and increased body fat mass. Moreover, the change in HOMA-IR was tightly correlated with the change in TGs. Surprisingly, change in adipocyte volume during follow-up was not correlated with WR nor with other factors, but positive correlations between adipocyte volume and HOMA-IR were found at the beginning and end of the follow-up.

CONCLUSION

These results suggest that TGs and IL-6 are independently linked to WR via separate mechanisms, and that HOMA-IR and adipocyte volume may indirectly link to WR through the change of plasma TGs.

Weight regain after bariatric surgery: Promoters and potential predictors

Obesity is globally viewed as chronic relapsing disease. Bariatric surgery offers the most efficient and durable weight loss approach. However, weight regain after surgery is a distressing issue as obesity can revert. Surgical procedures were originally designed to reduce food intake and catalyze weight loss, provided that its role is marginalized in long-term weight maintenance. Consequently, it is essential to establish a scientifically standardized applicable definitions for weight regain, which necessitates enhanced comprehension of the clinical situation, as well as have realistic expectations concerning weight loss. Moreover, several factors are proposed to influence weight regain as psychological, behavioral factors, hormonal, metabolic, anatomical lapses, as well as genetic predisposition. Recently, there is a growing evidence of utilization of scoring system to anticipate excess body weight loss, along with characterizing certain biomarkers that identify subjects at risk of suboptimal weight loss after surgery. Furthermore, personalized counseling is warranted to help select bariatric procedure, reinforce self-monitoring skills, motivate patient, encourage mindful eating practices, to avoid recidivism.

Dissociation Between Long-term Weight Loss Intervention and Blood Pressure: an 18-month Randomized Controlled Trial

BACKGROUND

Obesity is associated with elevated blood pressure (BP). In patients with obesity and hypertension, weight loss lowers BP, but the long-term effect of weight loss on BP is less clear.

OBJECTIVE

We aimed to assess the effect of long-term weight loss intervention on BP in normotensive and hypertensive subjects.

DESIGN

Randomized controlled trial.

PARTICIPANTS

Two hundred seventy-eight subjects (mean age 47.9 ± 9.3 years, 89% male, 56% hypertensive) with abdominal obesity or elevated serum triglycerides and low high-density lipoprotein cholesterol were recruited.

INTERVENTION

Eighteen-month weight loss intervention.

MAIN MEASURES

Body weight and BP were measured at baseline, after 6 and 18 months.

RESULTS

After 6 months of intervention, in the weight loss phase, body mass index (BMI) decreased by an average of -2.2±1.5 kg/m² (p<0.001) and both diastolic BP (DBP) and systolic BP (SBP) decreased by -2.1±8.8 mmHg and -2.3±12.9 mmHg, respectively (p<0.01 for both). The change in BMI was similar in normotensive and hypertensive subjects (-2.0±1.6 and -2.3±1.5, p = 0.246). However, DBP and SBP decreased significantly (-5.2±7.1 mmHg and -6.2±12.5 mmHg, respectively, p<0.001 for both) in hypertensive subjects, and increased in normotensive subjects (1.8±9.3 mmHg, p = 0.041 and 2.7±11.7 mmHg, p = 0.017, respectively). After 18 months, in the weight maintenance phase, BMI slightly increased (0.9±1.3 kg/m², p<0.001) but remained significantly lower than at baseline (p<0.0001). Unlike BMI, DBP and SBP increased significantly in hypertensive subjects (p<0.001) and returned almost to baseline levels.

CONCLUSION

Weight-loss intervention reduced BP in hypertensive patients, but this was not maintained in the long run.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01530724.

Describing the Weight-Reduced State: Physiology, Behavior, and Interventions

Although many persons with obesity can lose weight by lifestyle (diet and physical activity) therapy, successful long-term weight loss is difficult to achieve, and most people who lose weight regain their lost weight over time. The neurohormonal, physiological, and behavioral factors that promote weight recidivism are unclear and complex. The National Institute of Diabetes and Digestive and Kidney Diseases convened a workshop in June 2019, titled "The Physiology of the Weight-Reduced State," to explore the mechanisms and integrative physiology of adaptations in appetite, energy expenditure, and thermogenesis that occur in the weight-reduced state and that may oppose weight-loss maintenance. The proceedings from the first session of this workshop are presented here. Drs. Michael Rosenbaum, Kevin Hall, and Rudolph Leibel discussed the physiological factors that contribute to weight regain; Dr. Michael Lowe discussed the biobehavioral issues involved in weight-loss maintenance; Dr. John Jakicic discussed the influence of physical activity on long-term weight-loss maintenance; and Dr. Louis Aronne discussed the ability of drug therapy to maintain weight loss.

Gender Differences in Factors Associated with Clinically Meaningful Weight Loss among Adults Who Were Overweight or Obese: A Population-Based Cohort Study

OBJECTIVES

The impact of heterogeneity on gender difference for achieving clinically meaningful weight loss (cmWL) remains unclear. Here, we explored the potential gender differences in factors associated with cmWL.

METHODS

A total of 60,668 participants with body mass index (BMI) ≥25 kg/m2 at study entry and available BMI values at follow-up were included in this study. cmWL was defined as a weight loss of ≥5% from the study entry to follow-up. The associations of social-demographic factors, personal history of chronic diseases, lifestyle behaviors, and history of BMI with cmWL were evaluated using logistic regression models.

RESULTS

During a median follow-up of 9.13 years, 26.6% of the participants had a cmWL (30.8% for females vs. 23.1% in males; p < 0.001). Participants with older age, obesity at study entry, being more physical activity compared to 10 years ago, being relapsed smokers or consistent current smokers, having a history of chronic diseases (i.e., diabetes, osteoporosis, and stroke), cancer diagnosis during the study period, and more than 10-year follow-up were more likely to achieve cmWL in both males and females (all p < 0.05). The new smoking quitters and participants with less active in physical activity compared to 10 years ago were less likely to achieve cmWL in both males and females (all p < 0.05). Specifically, males with a history of emphysema were more likely to reach cmWL, and for females, those being overweight at 20 years old and current drinkers were more likely to reach cmWL (p < 0.05). Sensitivity analyses demonstrated similar results.

CONCLUSION

Age, BMI status, physical activity, smoking status, family income, and health status were independent factors in males and females for weight management. However, further well-designed prospective studies are warranted to confirm our findings.

Mechanisms of weight regain after weight loss - the role of adipose tissue

One of the biggest challenges in the management of obesity is the prevention of weight regain after successful weight loss. Weight regain after weight loss has large interindividual variation. Although many factors probably contribute to this variation, we hypothesize that variability in biological responses associated with weight loss-induced shrinking of subcutaneous adipocytes has an important role. In this Review, we show that weight loss-induced variations in cellular stress, extracellular matrix remodelling, inflammatory responses, adipokine secretion and lipolysis seem to be associated with the amount of weight that is regained after successful weight loss. Weight regain could therefore, at least in part, depend on a combination of these factors. Further research on the causality of these associations could aid the development of effective strategies to prevent weight regain after successful weight loss.

Comparative Expression of Renin-Angiotensin Pathway Proteins in Visceral Versus Subcutaneous Fat

Body fat distribution contributes to obesity-related metabolic and cardiovascular disorders. Visceral fat is more detrimental than subcutaneous fat. However, the mechanisms underlying visceral fat-mediated cardiometabolic dysregulation are not completely understood. Localized increases in expression of the renin angiotensin system (RAS) in adipose tissue (AT) may be implicated. We therefore investigated mRNA and protein expression of RAS components in visceral versus subcutaneous AT using paired samples from individuals undergoing surgery (N = 20, body mass index: 45.6 ± 6.2 kg/m², and age: 44.6 ± 9.1 years). We also examined RAS-related proteins in AT obtained from individuals on renin angiotensin aldosterone system (RAAS) targeted drugs (N = 10, body mass index: 47.2 ± 9.3 kg/m², and age: 53.3 ± 10.1 years). Comparison of protein expression between subcutaneous and visceral AT samples showed an increase in renin (p = 0.004) and no change in angiotensinogen (p = 0.987) expression in visceral AT. Among proteins involved in angiotensin peptide generation, angiotensin converting enzyme (p = 0.02) was increased in subcutaneous AT while chymase (p = 0.001) and angiotensin converting enzyme-2 (p = 0.001) were elevated in visceral fat. Furthermore, visceral fat expression of angiotensin II type-2 receptor (p = 0.007) and angiotensin II type-1 receptor (p = 0.031) was higher, and MAS receptor (p < 0.001) was lower. Phosphorylated-p53 (p = 0.147), AT fibrosis (p = 0.138) and average adipocyte size (p = 0.846) were similar in the two depots. Nonetheless, visceral AT showed increased mRNA expression of inflammatory (TNFα, p < 0.001; IL-6, p = 0.001) and oxidative stress markers (NOX2, p = 0.038; NOX4, p < 0.001). Of note, mRNA and protein expression of RAS components did not differ between subjects taking or not taking RAAS related drugs. In summary, several RAS related proteins are differentially expressed in subcutaneous versus visceral AT. This differential expression may not alter AngII but likely increases Ang1-7 generation in visceral fat. These potential differences in active angiotensin peptides and receptor expression in the two depots suggest that localized RAS may not be involved in differences in visceral vs subcutaneous AT function in obese individuals. Our findings do not support a role for localized RAS differences in visceral fat-mediated development of cardiovascular and metabolic pathology.

C-terminal degradation of PYY peptides in plasma abolishes effects on satiety and beta-cell function

The importance of dipeptidyl peptidase-4 mediated N-terminal metabolism of the enteroendocrine-derived hormone, peptide YY (PYY), for receptor binding and subsequent biological action profile is well established. However, an intact C-terminus may be fundamental also for bioactivity of PYY peptides. The current study has demonstrated C-terminal degradation of the major recognised circulating forms of PYY, PYY(1-36) and PYY(3-36), in plasma, resulting in production of PYY(1-34) and PYY(3-34). Interestingly, the angiotensin-converting-enzyme (ACE) inhibitor, captopril, blocked formation of PYY(3-34) from PYY(3-36) in plasma, but did result in the appearance of PYY(3-35). In addition, we were able to evidence C-terminal truncation of PYY(1-35) and PYY(3-35) to PYY(1-34) and PYY(3-34), respectively. As expected, PYY(1-36) and PYY(3-36) inhibited (P < 0.05-P < 0.001) glucose- and alanine-stimulated insulin secretion from BRIN-BD11 beta-cells. In contrast, PYY(1-34), PYY(3-34), PYY(1-35) and PYY(3-35) were devoid of insulinostatic actions. Both PYY(1-36) and PYY(3-36), but not related PYY metabolites, significantly (P < 0.05-P < 0.001) enhanced proliferation of BRIN BD11 and 1.1B4 beta-cell lines, and protected (P < 0.01-P < 0.001) these cell lines against cytokine-induced apoptosis. As expected, PYY(3-36) induced clear (P < 0.05-P < 0.01) appetite suppressive effects in mice, but this action was eliminated by mono- or di-peptide C-terminal truncation. Interestingly, captopril significantly (P < 0.05) augmented the anorexigenic effects of PYY(3-36) in mice. PYY(1-36), PYY(3-36), PYY(1-34) and PYY(3-34) lacked effects on in vivo glucose tolerance or glucose-induced insulin release. Taken together, these data highlight the unrecognised importance of C-terminal integrity of PYY peptides for biological activity and therapeutic usefulness in obesity-diabetes.

The Effects of Exercise and Physical Activity on Weight Loss and Maintenance

Obesity represents a major health problem in the United States and is associated with increased prevalence of cardiovascular (CV) disease risk factors. Physical activity (PA) and exercise training (ET) are associated with reduced CV risk, improved cardiometabolic risk factors, and facilitated weight loss through creating a negative energy balance. Clinicians need to counsel overweight and obese patients on how much PA/ET is needed to promote weight loss and weight loss maintenance. This will help establish realistic expectations and maximize improvements in CV risk factors. Although the minimum guidelines for aerobic PA (150 min of moderate or 75 min of vigorous physical activity per week) can improve CV health, these levels are generally inadequate for clinically significant weight loss or weight maintenance without caloric restriction. The purpose of this review is to evaluate the role of ET to promote clinically significant weight loss and promote weight maintenance. In particular, we will evaluate the likelihood of weight loss from ET programs composed of aerobic training only, resistance training only and programs that combine diet and ET. We will also explore the role of PA in promoting short-term and long-term weight maintenance.

Dietary weight loss-induced changes in RBP4, FFA, and ACE predict weight regain in people with overweight and obesity

Adipokines and other biomarkers were previously identified with roles in energy expenditure, appetite, satiety, and adiposity. Therefore, we investigated whether dietary weight loss‐induced changes in adipokines and other biomarkers known to play a role in weight regulation or energy expenditure could predict weight regain in people with overweight and obesity. In this randomized controlled trial 26 males and 30 females (BMI: 28–35 kg/m²) followed either a low‐calorie diet (LCD; 1250 kcal/day) for 12 weeks or a very‐low‐calorie diet (VLCD; 500 kcal/day) for 5 weeks followed by a weight stable period of 4 weeks (dietary intervention (DI) period) and a 9‐month follow‐up period. Blood samples were taken before and after each period to measure FFA, TAG, total cholesterol, insulin, glucose, angiotensin‐converting enzyme (ACE) activity, IL‐6, RBP4, apelin, leptin, adiponectin, vaspin, and nesfatin‐1 concentrations. Weight loss was similar between groups (LCD: −8.2 ± 0.5 kg; VLCD: −8.9 ± 0.4 kg, P = 0.30). Only changes in ACE activity, FFA and RBP4 concentrations during DI were correlated with weight regain in the whole group (r = −0.299, P = 0.030, r = −0.274, P = 0.047, and r = 0.357, P = 0.008, respectively). Together they explained 28% (r = 0.532) of weight regain variation. Dietary weight loss‐induced changes in ACE activity, FFA and RBP4 independently contribute to weight regain prediction.

Angiotensin-Converting Enzyme (ACE) D Allele as a Risk Factor for Increase Serum Interleukin-6 and Interleukin-8 in Psoriasis Patients

BACKGROUND:

Psoriasis is a chronic, recurrent inflammatory skin disease. It is characterised by autoimmune, environmental factors and complex genetic disorder.

AIM:

To explore the role of IL-6, IL-8, and ACE I/D polymorphism in the pathogenesis of Psoriasis and investigation of the relationship between ACE polymorphism and occurrence of psoriasis.

PATIENTS AND METHODS:

In this study, we took 73 psoriasis patients and 47 healthy patients as a control. These two groups subjected to analysis for ACE gene I/D polymorphism by PCR and biochemical methods.

RESULTS:

The serum levels of ACE, IL-8 and IL-6 were statistically significantly higher in psoriasis patients compared to healthy subjects (P < 0.001). ID and DD polymorphism were more common in psoriasis patients than healthy subjects. Also, D allele was significantly over-represented in patients compared to controls (52.7% Vs 35.1%).

CONCLUSION:

ACE gene polymorphism might grant susceptibility to develop psoriasis.

Metabolic Benefits of Prior Weight Loss with and without Exercise on Subsequent 6-Month Weight Regain

OBJECTIVE

To determine the 6-month follow-up effects after intentional 6-month weight loss alone (WL) and after weight loss with aerobic exercise (AEX + WL) on body composition, glucose metabolism, and cardiovascular disease risk factors in older postmenopausal women and to identify the mechanisms for weight regain.

METHODS

Women (n = 65, BMI > 25 kg/m² ) underwent maximal oxygen consumption testing, dual-energy x-ray absorptiometry, computed tomography scans, and oral glucose tolerance tests before and after 6 months of AEX + WL or WL and at 12 months ad libitum follow-up. Insulin sensitivity (M) (hyperinsulinemic-euglycemic clamp) was measured at baseline and 6 months. Thirty WL and thirty-five AEX + WL women completed a follow-up at 12 months.

RESULTS

Similar weight loss was observed (-8%) in both groups from 0 to 6 months. Total fat mass, fat-free mass, visceral fat area, subcutaneous abdominal and midthigh fat areas, fasting glucose, insulin levels, homeostatic model assessment of insulin resistance (HOMA-IR), insulin areas under the curve, and triglyceride levels decreased similarly after WL and AEX + WL and remained lower at 12 months than at baseline, despite weight regain at 12 months. Initial M was associated with weight regain (r = -0.40, P < 0.01). Weight regain was related to independent changes in leptin and HOMA-IR from 6 to 12 months in a multiple regression model (r = 0.77, P < 0.0001).

CONCLUSIONS

Reductions in body fat and improvements in insulin sensitivity after AEX + WL and WL were maintained at 12 months despite modest weight regain. Baseline insulin resistance partially predicted the magnitude of weight regain in postmenopausal women.

Dietary Fat Intake Modulates Effects of a Frequent ACE Gene Variant on Glucose Tolerance with association to Type 2 Diabetes

The frequent ACE insertion/deletion polymorphism (I/D) is, albeit inconsistently, associated with impaired glucose tolerance and insulin resistance. We recently observed an enhanced upregulation of ACE by elevated fat intake in GG-carriers of the I/D-surrogate rs4343 variant and therefore investigated its potential nutrigenetic role in glucose metabolism. In this nutritional intervention study 46 healthy and non-obese twin pairs consumed recommended low fat diets for 6 weeks before they received a 6-week high fat (HF) diet under isocaloric conditions. Intravenous glucose tolerance tests were performed before and after 1 and 6 weeks of HF diet. While glucose tolerance did not differ between genotypes at baseline it significantly declined in GG-carriers after 6 weeks HF diet (p = 0.001) with higher 2 h glucose and insulin concentrations compared to AA/AG-carriers (p = 0.003 and p = 0.042). Furthermore, the gene-diet interaction was confirmed in the cross-sectional Metabolic Syndrome Berlin Potsdam study (p = 0.012), with the GG-genotypes being significantly associated with prevalent type 2 diabetes for participants with high dietary fat intake ≥37% (GG vs. AA/AG, OR 2.36 [1.02-5.49], p = 0.045). In conclusion, the association between the rs4343 variant and glucose tolerance is modulated by dietary fat intake. The ACE rs4343 variant is a novel nutrient-sensitive type 2 diabetes risk marker potentially applicable for nutrigenetic dietary counseling.

Renin-angiotensin system blockers regulate the metabolism of isolated fat cells in vitro

Due to the presence of the renin-angiotensin system (RAS) in tissues and its specific influence on white adipose tissue, fat cells are possible targets of pharmacological RAS blockers commonly used as anti-hypertensive drugs. In the present study, we investigated the effects of different RAS blockers on fat cell metabolism, more specifically on lipolysis, lipogenesis and oxidation of energy substrates. Isolated primary adipocytes were incubated with different RAS blockers (aliskiren, captopril and losartan) in vitro for 24 h and lipolysis, lipogenesis and glucose oxidation capacities were determined in dose-response assays to a β-adrenergic agonist and to insulin. Although no change was found in lipolytic capacity, the RAS blockers modulated lipogenesis and glucose oxidation in a different way. While captopril decreased insulin-stimulated lipogenesis (−19% of maximal response and −60% of insulin responsiveness) due to reduced glucose derived glycerol synthesis (−19% of maximal response and 64% of insulin responsiveness), aliskiren increased insulin-stimulated glucose oxidation (+49% of maximal response and +292% of insulin responsiveness) in fat cells. Our experiments demonstrate that RAS blockers can differentially induce metabolic alterations in adipocyte metabolism, characterized by a reduction in lipogenic responsiveness or an increase in glucose oxidation. The impact of RAS blockers on adipocyte metabolism may have beneficial implications on metabolic disorders during their therapeutic use in hypertensive patients.

Genetic Predictors of ≥5% Weight Loss by Multidisciplinary Advice to Severely Obese Subjects

BACKGROUND

Weight loss success is determined by genetic factors, which may differ according to treatment strategy.

METHODS

From a multidisciplinary obesity treatment program involving dietary advice, psychological counseling, and increased physical activity, 587 subjects (68% female; 46.1 ± 12.4 years; BMI 39.9 ± 6.3) were recruited. At baseline, a blood sample was drawn for DNA isolation. Genotypes were determined for 30 polymorphisms in 25 candidate genes. The association between genotypes and weight loss was assessed after 3 months (short-term) and after 12 months of treatment (long-term). Weight loss was categorized as ≥5% or <5% of initial weight.

RESULTS

The G/G genotype of PLIN1 (rs2289487) and PLIN1 (rs2304795), the T/T genotype of PLIN1 (rs1052700), and the C/C genotype of MMP2 predicted ≥5% weight loss in the first 3 months. The C/G-G/G genotype of PPARγ (rs1801282) and the T/C genotype of TIMP4 (rs3755724) predicted ≥5% weight loss after 12 months. Subjects with the combination of PPARγ (rs1801282) C/G-G/G and TIMP4 (rs3755724) T/C lost even more weight.

CONCLUSION

Polymorphisms in genes related to regulation of fat storage and structural adaptation of the adipocytes are predictors for weight loss success with different genes being relevant for short-term and long-term weight loss success.

High-Saturated-Fat Diet Increases Circulating Angiotensin-Converting Enzyme, Which Is Enhanced by the rs4343 Polymorphism Defining Persons at Risk of Nutrient-Dependent Increases of Blood Pressure

BACKGROUND

Angiotensin-converting enzyme (ACE) plays a major role in blood pressure regulation and cardiovascular homeostasis. Contrary to the assumption that ACE levels are stable, circulating ACE has been shown to be altered in obesity and weight loss. We sought to examine effects of a high-saturated-fat (HF) diet on ACE within the NUtriGenomic Analysis in Twins (NUGAT) study.

METHODS AND RESULTS

Forty-six healthy and nonobese twin pairs initially consumed a carbohydrate-rich, low-fat diet over a period of 6 weeks to standardize for nutritional behavior prior to the study, followed by 6 weeks of HF diet under isocaloric conditions. After 6 weeks of HF diet, circulating ACE concentrations increased by 15% (P=1.6×10^-30), accompanied by an increased ACE gene expression in adipose tissue (P=3.8×10^-6). Stratification by ACE rs4343, a proxy for the ACE insertion/deletion polymorphism (I/D), revealed that homozygous carriers (GG) of the variant had higher baseline ACE concentrations (P=7.5×10^-8) and additionally showed a 2-fold increase in ACE concentrations in response to the HF diet as compared to non- or heterozygous carriers (AA/AG, P=2×10^-6). GG carriers also responded with higher systolic blood pressure as compared to AA/AG carriers (P=0.008). The strong gene-diet interaction was confirmed in a second independent, cross-sectional cohort, the Metabolic Syndrome Berlin Potsdam (MeSyBePo) study.

CONCLUSIONS

The HF-diet-induced increase of ACE serum concentrations reveals ACE to be a potential molecular link between dietary fat intake and hypertension and cardiovascular disease (CVD). The GG genotype of the ACE rs4343 polymorphism represents a robust nutrigenetic marker for an unfavorable response to high-saturated-fat diets.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01631123.

Weight loss-induced cellular stress in subcutaneous adipose tissue and the risk for weight regain in overweight and obese adults

BACKGROUND/OBJECTIVE

Weight loss is often followed by weight regain after the dietary intervention (DI). Cellular stress is increased in adipose tissue of obese individuals. However, the relation between cellular stress and weight regain is unclear. Previously, we observed increased adipose tissue cellular stress of participants regaining weight compared with participants maintaining weight loss. In the current study, we further investigated the relation between weight regain and changes in the expression of stress-related genes and stress protein levels to determine possible predictors of weight regain.

PARTICIPANTS/METHODS

In this randomized controlled trial, sixty-one healthy overweight/obese participants followed a DI of either a 5-week very-low-calorie diet (500 kcal per day) or a 12-week low-calorie diet (1250 kcal per day; WL period) with a subsequent 4-week weight stable diet (WS period), and a 9-month follow-up. The WL and WS period taken together was named the DI. Abdominal subcutaneous adipose tissue biopsies were collected in 53 participants for microarray and liquid chromatography-mass spectrometry analysis. RNA and protein levels for a broad set of stress-related genes were correlated to the weight regain percentage.

RESULTS

Different gene sets correlated to weight regain percentage during WS and DI. Bioinformatics clustering suggests that during the WS phase-defined genes for actin filament dynamics, glucose handling and nutrient sensing are related to weight regain. HIF-1 (hypoxia-inducible factor-1) is indicated as an important regulator. With regard to DI, clustering of correlated genes indicate that LGALS1, ENO1 and ATF2 are important nodes for conferring risk for weight regain.

CONCLUSIONS

Our present findings indicate that the risk for weight regain is related to expression changes of distinct sets of stress-related genes during the first 4 weeks after returning to energy balance, and during the DI. Further research is required to investigate the mechanistic significance of these findings and find targets for preventing weight regain.

Guide and Position of the International Society of Nutrigenetics/Nutrigenomics on Personalized Nutrition: Part 2 - Ethics, Challenges and Endeavors of Precision Nutrition

Nutrigenetics considers the influence of individual genetic variation on differences in response to dietary components, nutrient requirements and predisposition to disease. Nutrigenomics involves the study of interactions between the genome and diet, including how nutrients affect the transcription and translation process plus subsequent proteomic and metabolomic changes, and also differences in response to dietary factors based on the individual genetic makeup. Personalized characteristics such as age, gender, physical activity, physiological state and social status, and special conditions such as pregnancy and risk of disease can inform dietary advice that more closely meets individual needs. Precision nutrition has a promising future in treating the individual according to their phenotype and genetic characteristics, aimed at both the treatment and prevention of disease. However, many aspects are still in progress and remain as challenges for the future of nutrition. The integration of the human genotype and microbiome needs to be better understood. Further advances in data interpretation tools are also necessary, so that information obtained through newer tests and technologies can be properly transferred to consumers. Indeed, precision nutrition will integrate genetic data with phenotypical, social, cultural and personal preferences and lifestyles matters to provide a more individual nutrition, but considering public health perspectives, where ethical, legal and policy aspects need to be defined and implemented.

Weight loss-induced stress in subcutaneous adipose tissue is related to weight regain

Initial successful weight loss is often followed by weight regain after the dietary intervention. Compared with lean people, cellular stress in adipose tissue is increased in obese subjects. However, the relation between cellular stress and the risk for weight regain after weight loss is unclear. Therefore, we determined the expression levels of stress proteins during weight loss and weight maintenance in relation to weight regain. In vivo findings were compared with results from in vitro cultured human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes. In total, eighteen healthy subjects underwent an 8-week diet programme with a 10-month follow-up. Participants were categorised as weight maintainers or weight regainers (WR) depending on their weight changes during the intervention. Abdominal subcutaneous adipose tissue biopsies were obtained before and after the diet and after the follow-up. In vitro differentiated SGBS adipocytes were starved for 96 h with low (0·55 mm) glucose. Levels of stress proteins were determined by Western blotting. WR showed increased expressions of β-actin, calnexin, heat shock protein (HSP) 27, HSP60 and HSP70. Changes of β-actin, HSP27 and HSP70 are linked to HSP60, a proposed key factor in weight regain after weight loss. SGBS adipocytes showed increased levels of β-actin and HSP60 after 96 h of glucose restriction. The increased level of cellular stress proteins in the adipose tissue of WR probably resides in the adipocytes as shown by in vitro experiments. Cellular stress accumulated in adipose tissue during weight loss may be a risk factor for weight regain.

Weight regaining: From statistics and behaviors to physiology and metabolism

Achieving maintenance of weight loss is crucial to combat obesity. However, most individuals tend to regain weight. Data from successful maintainers show that they remain vigilant and constantly apply techniques to oppose the course of regaining. On the other hand, current advances in obesity research show that the reduced obese state is a state of altered physiology in terms of energy balance. This review describes the physiological adaptations occurring after weight loss that predispose to regaining. Specifically, changes regarding body composition, hormonal background, energy expenditure and control of food intake are discussed. Moreover, metabolites that can act as regain predictors and dietary techniques to oppose regaining are presented.

Opposing tissue-specific roles of angiotensin in the pathogenesis of obesity, and implications for obesity-related hypertension

Metabolic disease, specifically obesity, has now become the greatest challenge to improving cardiovascular health. The renin-angiotensin system (RAS) exists as both a circulating hormone system and as a local paracrine signaling mechanism within various tissues including the brain, kidney, and adipose, and this system is strongly implicated in cardiovascular health and disease. Growing evidence also implicates the RAS in the control of energy balance, supporting the concept that the RAS may be mechanistically involved in the pathogenesis of obesity and obesity hypertension. Here, we review the involvement of the RAS in the entire spectrum of whole organism energy balance mechanisms, including behaviors (food ingestion and spontaneous physical activity) and biological processes (digestive efficiency and both aerobic and nonaerobic resting metabolic rates). We hypothesize that opposing, tissue-specific effects of the RAS to modulate these various components of energy balance can explain the apparently paradoxical results reported by energy-balance studies that involve stimulating, versus disrupting, the RAS. We propose a model in which such opposing and tissue-specific effects of the RAS can explain the failure of simple, global RAS blockade to result in weight loss in humans, and hypothesize that obesity-mediated uncoupling of endogenous metabolic rate control mechanisms can explain the phenomenon of obesity-related hypertension.

Dietary Sodium Suppresses Digestive Efficiency via the Renin-Angiotensin System

Dietary fats and sodium are both palatable and are hypothesized to synergistically contribute to ingestive behavior and thereby obesity. Contrary to this hypothesis, C57BL/6J mice fed a 45% high fat diet exhibited weight gain that was inhibited by increased dietary sodium content. This suppressive effect of dietary sodium upon weight gain was mediated specifically through a reduction in digestive efficiency, with no effects on food intake behavior, physical activity, or resting metabolism. Replacement of circulating angiotensin II levels reversed the effects of high dietary sodium to suppress digestive efficiency. While the AT₁ receptor antagonist losartan had no effect in mice fed low sodium, the AT₂ receptor antagonist PD-123,319 suppressed digestive efficiency. Correspondingly, genetic deletion of the AT₂ receptor in FVB/NCrl mice resulted in suppressed digestive efficiency even on a standard chow diet. Together these data underscore the importance of digestive efficiency in the pathogenesis of obesity, and implicate dietary sodium, the renin-angiotensin system, and the AT₂ receptor in the control of digestive efficiency regardless of mouse strain or macronutrient composition of the diet. These findings highlight the need for greater understanding of nutrient absorption control physiology, and prompt more uniform assessment of digestive efficiency in animal studies of energy balance.

NIH working group report: Innovative research to improve maintenance of weight loss

OBJECTIVES

The National Institutes of Health, led by the National Heart, Lung, and Blood Institute, organized a working group of experts to discuss the problem of weight regain after weight loss. A number of experts in integrative physiology and behavioral psychology were convened with the goal of merging their perspectives regarding the barriers to scientific progress and the development of novel ways to improve long-term outcomes in obesity therapeutics. The specific objectives of this working group were to: (1) identify the challenges that make maintaining a reduced weight so difficult; (2) review strategies that have been used to improve success in previous studies; and (3) recommend novel solutions that could be examined in future studies of long-term weight control.

RESULTS

Specific barriers to successful weight loss maintenance include poor adherence to behavioral regimens and physiological adaptations that promote weight regain. A better understanding of how these behavioral and physiological barriers are related, how they vary between individuals, and how they can be overcome will lead to the development of novel strategies with improved outcomes.

CONCLUSIONS

Greater collaboration and cross-talk between physiological and behavioral researchers is needed to advance the science and develop better strategies for weight loss maintenance.

Gender-specific genetic associations of polymorphisms in ACE, AKR1C2, FTO and MMP2 with weight gain over a 10-year period

Weight gain, when it leads to overweight or obesity, is nowadays one of the major health problems. ACE, FTO, AKR1C2, TIMP4 and MMP2 genes have been implicated in previous studies on weight regulation. This study investigated the contribution of polymorphisms in these five candidate genes to the risk of weight gain over a 10-year time period. Two groups were selected from participants of the Doetinchem cohort study who were followed over a 10-year period: A stable weight group (±2 kg/10 year; n = 259) and a weight gainers group who increased their body weight by roughly 10 % (>8 kg/10 year; n = 237). Starting BMI was between 20 and 35 kg/m(2) and baseline age between 20 and 45 years. Selected SNPs and insert/deletion in candidate genes were measured in each group. In men, the allelic distribution of FTO rs9939609 (χ (2) p = 0.005), ACE rs4340 (χ (2) p = 0.006) and AKR1C2 rs12249281 (χ (2) p = 0.019) differed between the weight stable and weight gainers group. Interaction between FTO rs9939609 and ACE rs4340 was observed. In women, the allelic distribution of MMP2 rs1132896 differed between the weight stable and weight gainers group (χ (2) p = 0.00001). The A-allele of FTO was associated with a 1.99× higher risk of gaining weight in men (OR 1.99, p = 0.020), while in women, the C-allele of MMP2 was associated with a 2.50× higher risk of weight gain (OR 2.50, p = 0.001) over the 10-year period. We found that FTO in men and MMP2 in women are associated with weight gain over a 10-year follow-up period.

PreDictor Research in Obesity during Medical care - weight Loss in children and adolescents during an INpatient rehabilitation: rationale and design of the DROMLIN study

BACKGROUND

Obesity in adults and children is increasing worldwide at alarming rates. Obese children and adolescents are likely to become obese adults with increased risk of a number of comorbidities. In addition to preventing the development of obesity at young age, it is necessary to individualize the therapy of already obese children and adolescents in order to increase the likelihood of weight loss and maintenance. Therefore, the aim of this study is to identify predictors which play a significant role in successful weight loss and weight loss maintenance in children and adolescents.

METHODS/DESIGN

Over a one year period, 60 obese children and adolescents between 9 to 17 years of age shall be recruited at an inpatient children rehabilitation facility in Germany. They will be investigated twice within a few days following admission and prior to discharge. The study will be an integrated component of an established inpatient weight-loss and in part psychosomatic therapy. The collected data can be grouped into four clusters: 1) demographic, sociometric and psychometric data, 2) objective and subjective parameters of body condition, 3) autonomic nervous system regulated functions and 4) objective and subjective parameters for eating behavior. Primary outcome is the change of the body mass index standard deviation score (BMI-SDS). In order to evaluate the data appropriately, all examinations will be also conducted in a normal-weight reference group, matched for age and gender.

DISCUSSION

For some of the collected parameters the time span between measures may be too short. Therefore, a 6 months, 1 year and 2 year follow-up will be performed for evaluating the different predictors and their influence in regard to a successful intervention. Further middle- and long-term follow-up studies are planned.

TRIAL REGISTRATION

The study protocol was approved by the Ethics Committee of the University Hospital Tübingen, Germany. This study is registered at the German Clinical Trials Register (DRKS) with the clinical trial number DRKS00005122.

Impact of weight regain on metabolic disease risk: a review of human trials

Dietary restriction interventions are effective for weight loss and reduction of chronic disease risk. Unfortunately, most people tend to regain much of this lost weight within one year after intervention. While some studies suggest that minor degrees of weight regain have no effect on metabolic disease risk parameters, other studies demonstrate a complete reversal in metabolic benefits. In light of these conflicting findings, it is of interest to determine how complete weight maintenance versus mild weight regain affects key risk parameters. These findings would have important clinical implications, as they could help identify a weight regain threshold that could preserve the metabolic benefits of weight loss. Accordingly, this review examined the impact of no weight regain versus mild regain on various metabolic disease risk parameters, including plasma lipids, blood pressure, glucose, and insulin concentrations, in adult subjects.

Caloric restriction induces changes in insulin and body weight measurements that are inversely associated with subsequent weight regain

BACKGROUND

Successful weight maintenance following weight loss is challenging for many people. Identifying predictors of longer-term success will help target clinical resources more effectively. To date, focus has been predominantly on the identification of predictors of weight loss. The goal of the current study was to determine if changes in anthropometric and clinical parameters during acute weight loss are associated with subsequent weight regain.

METHODOLOGY

The study consisted of an 8-week low calorie diet (LCD) followed by a 6-month weight maintenance phase. Anthropometric and clinical parameters were analyzed before and after the LCD in the 285 participants (112 men, 173 women) who regained weight during the weight maintenance phase. Mixed model ANOVA, Spearman correlation, and linear regression were used to study the relationships between clinical measurements and weight regain.

PRINCIPAL FINDINGS

Gender differences were observed for body weight and several clinical parameters at both baseline and during the LCD-induced weight loss phase. LCD-induced changes in BMI (Spearman's ρ = 0.22, p = 0.0002) were inversely associated with weight regain in both men and women. LCD-induced changes in fasting insulin (ρ = 0.18, p = 0.0043) and HOMA-IR (ρ = 0.19, p = 0.0023) were also associated independently with weight regain in both genders. The aforementioned associations remained statistically significant in regression models taking account of variables known to independently influence body weight.

CONCLUSIONS/SIGNIFICANCE

LCD-induced changes in BMI, fasting insulin, and HOMA-IR are inversely associated with weight regain in the 6-month period following weight loss.

Metabolic rate regulation by the renin-angiotensin system: brain vs. body

Substantial evidence supports a role for the renin-angiotensin system (RAS) in the regulation of metabolic function, but an apparent paradox exists where genetic or pharmacological inhibition of the RAS occasionally has similar physiological effects as chronic angiotensin infusion. Similarly, while RAS targeting in animal models has robust metabolic consequences, effects in humans are more subtle. Here, we review the data supporting a role for the RAS in metabolic rate regulation and propose a model where the local brain RAS works in opposition to the peripheral RAS, thus helping to explain the paradoxically similar effects of RAS supplementation and inhibition. Selectively modulating the peripheral RAS or brain RAS may thus provide a more effective treatment paradigm for obesity and obesity-related disorders.