Different dietary strategies for weight loss in obesity: role of energy and macronutrient content

Effect of planned pauses versus continuous energy restriction on weight loss and attrition: a systematic review

OBJECTIVE

The objective of this study was to investigate whether pausing a weight loss program for a defined period of time could enhance weight loss and reduce attrition.

METHODS

Five databases and two trial registries were searched from inception to July 2023. Randomized-controlled trials of adults with overweight and/or obesity were included if they compared planned-pause interventions with continuous energy restriction (CER), usual care, or a minimal intervention. To be included, the weight loss intervention must have incorporated a pause of at least 1 week. Pooled mean differences for weight change and risk ratios for attrition were calculated using random-effects meta-analyses.

RESULTS

Nine intervention arms (N = 796 participants, 77% female) were included. Pooled results did not detect a significant difference in weight change between planned pauses and CER interventions at the end of the active intervention at a median 26 weeks (planned pauses vs. CER mean: -7.09 vs. -7.0 kg; mean difference: -0.09 kg; 95% CI: -1.10 to 0.93) or at final follow-up at a median 52 weeks (planned pauses vs. CER mean: -6.91 vs. -6.19 kg; mean difference: -0.72 kg; 95% CI: -2.92 to 1.48). There was no difference in attrition between planned pauses and CER interventions at the end of the active intervention (risk ratio: 1.20, 95% CI: 0.82 to 1.75) or at final follow-up (risk ratio: 1.04, 95% CI: 0.89 to 1.22).

CONCLUSIONS

Planned pauses were consistently found to be no more or less effective than CER for weight loss or attrition.

The Effectiveness of Nutritional Strategies in the Treatment and Management of Obesity: A Systematic Review

Obesity, a condition primarily resulting from positive energy balance, has become a significant global health concern. Numerous studies have demonstrated that obesity is a major risk factor for various illnesses, including different types of cancer, coronary heart disease, sleep apnea, CV stroke, type II diabetes mellitus, etc. To effectively address this issue, prevention and treatment approaches to manage body weight are crucial. There are several evidence-based approaches available for the treatment and management of obesity, taking into account factors such as body mass index classification, individual weight history, and existing comorbidities. To facilitate successful obesity treatment and management, there are pragmatic approaches and tools available, including the reduction of energy density, portion control, and diet quality enhancement. These approaches encompass the use of medications, lifestyle interventions, bariatric surgery, and formula diets. Regardless of the specific method employed, behavior change, reduction of energy intake, and increased energy expenditure are integral components for successful treatment and management of obesity. These measures allow patients to personalize and customize their dietary patterns, leading to effective and sustainable weight reduction. Incorporating physical activities and self-monitoring of individual diets are effective techniques for promoting behavior change in obesity and weight management. The main objective of this systematic review is to evaluate the effectiveness of dietary/nutritional interventions in the treatment and management of obesity through provision of valuable insights into the effectiveness of such nutritional strategies. To attain this, a comprehensive analysis of various dietary approaches and their impacts on weight will be conducted.

Identification of adipose tissue transcriptomic memory of anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is a complex debilitating disease characterized by intense fear of weight gain and excessive exercise. It is the deadliest of any psychiatric disorder with a high rate of recidivism, yet its pathophysiology is unclear. The Activity-Based Anorexia (ABA) paradigm is a widely accepted mouse model of AN that recapitulates hypophagia and hyperactivity despite reduced body weight, however, not the chronicity.

METHODS

Here, we modified the prototypical ABA paradigm to increase the time to lose 25% of baseline body weight from less than 7 days to more than 2 weeks. We used this paradigm to identify persistently altered genes after weight restoration that represent a transcriptomic memory of under-nutrition and may contribute to AN relapse using RNA sequencing. We focused on adipose tissue as it was identified as a major location of transcriptomic memory of over-nutririon.

RESULTS

We identified 300 dysregulated genes that were refractory to weight restroration after ABA, including Calm2 and Vps13d, which could be potential global regulators of transcriptomic memory in both chronic over- and under-nutrition.

CONCLUSION

We demonstrated the presence of peristent changes in the adipose tissue transcriptome in the ABA mice after weight restoration. Despite being on the opposite spectrum of weight perturbations, majority of the transcriptomic memory genes of under- and over-nutrition did not overlap, suggestive of the different mechanisms involved in these extreme nutritional statuses.

Obesity in South and Southeast Asia-A new consensus on care and management

Obesity is a chronic disease in which the abnormal or excessive accumulation of body fat leads to impaired health and increased risk of mortality and chronic health complications. Prevalence of obesity is rising rapidly in South and Southeast Asia, with potentially serious consequences for local economies, healthcare systems, and quality of life. Our group of obesity specialists from Bangladesh, Brunei Darussalam, India, Indonesia, Malaysia, Philippines, Singapore, Sri Lanka, Thailand, and Viet Nam undertook to develop consensus recommendations for management and care of adults and children with obesity in South and Southeast Asia. To this end, we identified and researched 12 clinical questions related to obesity. These questions address the optimal approaches for identifying and staging obesity, treatment (lifestyle, behavioral, pharmacologic, and surgical options) and maintenance of reduced weight, as well as issues related to weight stigma and patient engagement in the clinical setting. We achieved consensus on 42 clinical recommendations that address these questions. An algorithm describing obesity care is presented, keyed to the various consensus recommendations.

Serum Metabolomics Analysis for Biomarkers of Lactobacillus plantarum FRT4 in High-Fat Diet-Induced Obese Mice

Lactobacillus plantarum is considered a potential probiotic supplementation for treating obesity. However, the underlying molecular mechanism is poorly understood. Our previous study displayed that L. plantarum FRT4 alleviated obesity in mice fed a high-fat diet (HFD) through ameliorating the HFD-induced gut microbiota dysbiosis. To explore the roles of FRT4 in obesity prevention, in this study, we investigated changes in serum metabolomic phenotype by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF/MS) and analyzed the pathway of HFD-fed Kunming female mice orally administered with FRT4 for eight weeks. Using orthogonal partial least squares discriminant analysis (OPLS-DA), metabolite patterns with significant changes were observed. 55 metabolites including phosphatidylcholine, lysophophatidylcholine, sphingomyelin, serotonin, indole-3-methyl aceta, indole-3-carbinol, indole-5,6-quino, 11,12-DHET, prostaglandin B2, leukotriene B4, and 3-hydroxybenzoic acid were identified as potential biomarkers associated with obesity, which were mainly involving in glycerophospholipid metabolism, tryptophan metabolism, and arachidonic acid metabolism. Perturbations of 14 biomarkers could be regulated by FRT4 intervention. These metabolites may serve as valuable biomarkers to understand the mechanisms by which intake of diets containing FRT4 contributes to the treatment or prevention of obesity. Thus, FRT4 can be a promising dietary supplement for the prevention of HFD-induced obesity.

Higher dietary insulin load and index are not associated with the risk of metabolic syndrome and obesity in Iranian adults

BACKGROUND

Data about the relation between dietary insulin load (DIL) and dietary insulin index (DII) with metabolic syndrome (MetS) and obesity are scarce. Therefore, the present study aimed to examine the association of the insulinemic potential of the diet with MetS and obesity amongst Iranian adults.

METHODS

This cross-sectional study was conducted amongst 850 adults aged 20-59 years. Dietary data were collected using a 168-item food frequency questionnaire. DIL was calculated using a standard formula and DII was obtained by dividing DIL by the total energy intake of each participant. The guidelines of the International Diabetes Federation were used to define MetS. General obesity was considered as body mass index ≥ 30 kg/m² , and abdominal obesity as waist circumference ≥ 94 cm for men and ≥ 80 cm for women.

RESULTS

Mean DIL and DII values were 101 684 ± 54 802 and 49.4 ± 33.4, respectively. The mean age of participants was 44.9 ± 10.7 years and 36.8%, 28.5% and 48.8% of participants were suffering from MetS, general and abdominal obesity, respectively. In contrast with DIL (P = .73), participants in the last quartile of DII (P = .62) had lower odds of MetS than the first quartile. There were non-significant inverse associations between DIL (P = .91, P = .85) and DII (P = .59, P = .53) with odds of general and abdominal obesity before and after the adjustment of confounders, respectively.

CONCLUSIONS

We did not observe any significant association of DIL and DII with the risk of MetS and obesity amongst the Iranian population. Further prospective studies are needed to confirm the findings of this study.

Understanding the interplay between food structure, intestinal bacterial fermentation and appetite control

Epidemiological and clinical evidence highlight the benefit of dietary fibre consumption on body weight. This benefit is partly attributed to the interaction of dietary fibre with the gut microbiota. Dietary fibre possesses a complex food structure which resists digestion in the upper gut and therefore reaches the distal gut where it becomes available for bacterial fermentation. This process yields SCFA which stimulate the release of appetite-suppressing hormones glucagon-like peptide-1 and peptide YY. Food structures can further enhance the delivery of fermentable substrates to the distal gut by protecting the intracellular nutrients during upper gastrointestinal digestion. Domestic and industrial processing can disturb these food structures that act like barriers towards digestive enzymes. This leads to more digestible products that are better absorbed in the upper gut. As a result, less resistant material (fibre) and intracellular nutrients may reach the distal gut, thus reducing substrates for bacterial fermentation and its subsequent benefits on the host metabolism including appetite suppression. Understanding this link is essential for the design of diets and food products that can promote appetite suppression and act as a successful strategy towards obesity management. This article reviews the current evidence in the interplay between food structure, bacterial fermentation and appetite control.

Bifidobacterium longum subsp. longum Remodeled Roseburia and Phosphatidylserine Levels and Ameliorated Intestinal Disorders and liver Metabolic Abnormalities Induced by High-Fat Diet

Bifidobacterium longum is considered as a potential supplement in antiobesity treatment; however, the underlying molecular mechanism has rarely been studied. To understand the contributions of B. longum subsp. longum (BL21) in the prevention of obesity, we investigated alterations in the liver metabonomic phenotype and gut microbiota by ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and 16S ribosomal RNA gene sequencing in C57BL/6J male mice orally administered with BL21 for 8 weeks [high-fat diet (HFD)]. BL21 at 1 × 109 CFU·day-1 per mouse reduced the weight of mice by 16.9% relative to that of the mice fed with HFD and significantly lowered the serum levels of total cholesterol, triglycerides, and low-density lipoprotein cholesterol. BL21 also ameliorated fat vacuolization in liver cells and epididymal fat accumulation. BL21 also lowered the Firmicutes/Bacteroidetes ratio, regulated liver remodeling in glycerophospholipids, and alleviated the levels of d-tryptophan. A positive correlation between the butyrate-producing strain Roseburia and the cell membrane component phosphatidylserine was found for the first time. Thus, BL21 can potentially prevent mice from being obese by rebalancing the gut microbiota and glycerophospholipid metabolism. BL21 can be a promising dietary supplement for weight control.

Lactobacillus rhamnosusLRa05 improves lipid accumulation in mice fed with a high fat dietviaregulating the intestinal microbiota, reducing glucose content and promoting liver carbohydrate metabolism

LRa05 resists obesityviaamelioratingStreptococcuslevel and glucose metabolism, moreover, the positive correlation betweenIntestinimonasand palmitoyl ethanolamide and the negative correlation betweenEnterorhabdusand vitamin B2 are first found.

Microspheres as carriers for lipase inhibitory substances to reduce dietary triglyceride absorption in mice

The present study intends to use microspheres as a delivery system of chlorogenic acid (CGA) to investigate the influences of CGA microspheres on dietary fat absorption and fecal triglyceride excretion in a mice model. Microspheres have an average particle size of about 53.3 μm. Results indicated that the microspheres were capable of gradually releasing the preloaded CGA into the surrounding medium. Their bioadhesive property might help prolong the gastrointestinal transit time in mice, and render a better mixing and contact between CGA and triglyceride. Consumption of CGA microspheres resulted in a significantly higher level of fecal triglyceride (119-144%) as compared with the corresponding control groups. A microsphere would be a desirable vehicle for CGA to improve its efficacy along the intestine.

Effects of a Macro-Nutrient Preload on Type 2 Diabetic Patients

AIMS

Macro-nutrient preloads given 30 min before regular meals may improve metabolism. The aim was to investigate how type 2 diabetic patients react to a preload consisting of a blend of macro-nutrients with a low-glycemic index (Inzone Preload(®)).

METHODS

In a before-after study design, 30 subjects with type 2 diabetes mellitus (T2DM) were enrolled in a 12-week program. All subjects were given Inzone Preload (43% proteins, 29% carbohydrates, 10% lipids, and 9% fibers, 71 kcal), 30 min before each meal during 12 weeks. Fasting glucose and postprandial 2 h glucose were monitored every second week. Body weight (BW) and waist circumference were measured each month. Fasting plasma glucose, glycosylated hemoglobin, serum lipids, fasting insulin, C-reactive protein, and homeostasis model assessment were evaluated before and after the intervention. Subjective appetite was monitored using visual analogue scales after the Inzone Preload.

RESULTS

The dietary intervention significantly influenced several metabolic parameters compared to base line. Inzone Preload treatment reduced mean postprandial plasma glucose levels (12.2 ± 1.2 vs. 10.5 ± 2.0 mmol/L), HbA1c (7.4 ± 0.3 vs. 7.1 ± 0.2%), mean total cholesterol (4.8 ± 0.9 vs. 4.3 ± 0.8 mmol/L), low-density lipoprotein cholesterol (2.8 ± 0.6 vs. 2.5 ± 0.4 mmol/L), and CRP (1.5 ± 1.4 vs. 0.7 ± 0.7 mg/L). BW loss of more than 3% was seen in 13 participants (43%). Feelings of satiety were significantly higher after Inzone Preload than after habitual breakfast (p < 0.05). No significant changes in fasting blood glucose, high-density lipoprotein and total triacylglycerol, HOMA-IR, and HOMA-β were observed.

CONCLUSION

A macro-nutrient preload treatment reduces postprandial glucose, inflammatory markers, and serum lipids in patients with T2DM. Approximately half of the study group also displayed reduced BW.

Protein leverage and energy intake

Increased energy intakes are contributing to overweight and obesity. Growing evidence supports the role of protein appetite in driving excess intake when dietary protein is diluted (the protein leverage hypothesis). Understanding the interactions between dietary macronutrient balance and nutrient-specific appetite systems will be required for designing dietary interventions that work with, rather than against, basic regulatory physiology. Data were collected from 38 published experimental trials measuring ad libitum intake in subjects confined to menus differing in macronutrient composition. Collectively, these trials encompassed considerable variation in percent protein (spanning 8-54% of total energy), carbohydrate (1.6-72%) and fat (11-66%). The data provide an opportunity to describe the individual and interactive effects of dietary protein, carbohydrate and fat on the control of total energy intake. Percent dietary protein was negatively associated with total energy intake (F = 6.9, P < 0.0001) irrespective of whether carbohydrate (F = 0, P = 0.7) or fat (F = 0, P = 0.5) were the diluents of protein. The analysis strongly supports a role for protein leverage in lean, overweight and obese humans. A better appreciation of the targets and regulatory priorities for protein, carbohydrate and fat intake will inform the design of effective and health-promoting weight loss diets, food labelling policies, food production systems and regulatory frameworks.

Pre-treatment circulating leptin/ghrelin ratio as a non-invasive marker to identify patients likely to regain the lost weight after an energy restriction treatment

BACKGROUND

Leptin and ghrelin appear to play a role in weight regain after a successful weight loss. The pre-treatment plasma levels of leptin/ghrelin ratio (L/G) could have power to predict this clinically relevant issue in the obesity treatment.

OBJECTIVE

To evaluate the ability of the L/G as a non-invasive tool for the early discrimination of obese patients who are more likely to regain weight after an energy restriction program (regainers) from those who maintain the lost weight (non-regainers).

SUBJECTS AND METHODS

Fasting leptin and ghrelin levels were evaluated in 88 overweight/obese patients who followed an 8-week hypocaloric diet program and were categorized as regainers (≥10 % weight-lost regain) and non-regainers (<10 % weight-lost regain) 6 months (32 weeks) after finishing the dietary treatment. A receiver operating characteristic (ROC) curve analysis was employed to evaluate the diagnostic value of the L/G ratio and to establish a cut-off point to differentiate regainers from non-regainers.

RESULTS

Regainers showed a statistically higher baseline (week 0) and after treatment (week 8) L/G ratio than non-regainers. The baseline L/G ratio was associated with an increased risk for weight regain (odds ratio 1.051; p = 0.008). Using the area under the ROC curve (AUC), the L/G ratio significantly identified female (AUC = 0.69; p = 0.040) and male regainers (AUC = 0.68; p = 0.030). The maximum combination of sensitivity and specificity was shown at the cut-off point of 26.0 for women and 9.5 for men.

CONCLUSIONS

The pre-intervention fasting leptin/ghrelin ratio could be a useful non-invasive approach to personalize obesity therapy and avoid unsuccessful treatment outcomes.

Ketogenic diets for weight loss: A review of their principles, safety and efficacy

SUMMARY

Low-carbohydrate "ketogenic" diets have increased in popularity over recent years as a means of weight loss. Published studies of these diets have been highly heterogeneous, and it remains unclear to what degree dietary carbohydrate intake must be restricted in order to induce ketosis. Despite concern that they are often relatively high in fat, ketogenic low-carbohydrate diets have been generally shown to compare favourably with low-fat diets in terms of weight loss and improvements in triglyceride and high-density lipoprotein levels. This review includes a brief overview of ketone body metabolism, and summarises the literature regarding the safety and efficacy of ketogenic diets for weight loss.:

Short- and long-term effects of continuous versus intermittent restrictive diet approaches on body composition and the metabolic profile in overweight and obese postmenopausal women: a pilot study

OBJECTIVE

The objective of this study was to compare changes in body composition and the metabolic profile between women taking an intermittent diet (ID) and women taking a continuous diet (CD).

METHODS

Twenty-five obese postmenopausal women were randomized to an ID (n = 13) or a CD (n = 12). In the ID, 5-week energy restriction periods were followed by 5-week weight stabilization periods. In the CD, 15 weeks of energy restriction was followed by 5 weeks of weight stabilization. Outcome measures before, during, and after weight loss, as well as after a 1-year follow-up, were body weight and composition, waist circumference, resting metabolic rate, and fasting lipid and glucose levels.

RESULTS

Body weight, waist circumference, percentage fat mass, and fat mass decreased significantly and similarly in both groups (P < 0.0001). Both groups showed similar overall decreases in plasma total cholesterol and triglycerides (all P < 0.05). Low-density lipoprotein cholesterol improved significantly in the CD group only, whereas fasting glucose decreased significantly in the ID group only. High-density lipoprotein cholesterol and resting metabolic rate remained stable in both groups. Fasting plasma triglyceride and glucose levels were the only metabolic variables to further improve after the fifth week of the protocol. At the 1-year follow-up, both interventions were associated with successful and similar weight loss maintenance and improvements in fasting plasma glucose levels.

CONCLUSIONS

The ID resulted in similar short- and long-term changes in body composition and metabolic profile compared with a CD. Most improvements occurred during the first 5 weeks of treatment in both interventions.

Usefulness of combining intermittent hypoxia and physical exercise in the treatment of obesity

Obesity is an important public health problem worldwide and is a major risk factor for a number of chronic diseases such as type II diabetes, adverse cardiovascular events and metabolic syndrome-related features. Different treatments have been applied to tackle body fat accumulation and its associated clinical manifestations. Often, relevant weight loss is achieved during the first 6 months under different dietary treatments. From this point, a plateau is reached, and a gradual recovery of the lost weight may occur. Therefore, new research approaches are being investigated to assure weight maintenance. Pioneering investigations have reported that oxygen variations in organic systems may produce changes in body composition. Possible applications of intermittent hypoxia to promote health and in various pathophysiological states have been reported. The hypoxic stimulus in addition to diet and exercise can be an interesting approach to lose weight, by inducing higher basal noradrenalin levels and other metabolic changes whose mechanisms are still unclear. Indeed, hypoxic situations increase the diameter of arterioles, produce peripheral vasodilatation and decrease arterial blood pressure. Furthermore, hypoxic training increases the activity of glycolytic enzymes, enhancing the number of mitochondria and glucose transporter GLUT-4 levels as well as improving insulin sensitivity. Moreover, hypoxia increases blood serotonin and decreases leptin levels while appetite is suppressed. These observations allow consideration of the hypothesis that intermittent hypoxia induces fat loss and may ameliorate cardiovascular health, which might be of interest for the treatment of obesity. This new strategy may be useful and practical for clinical applications in obese patients.

Effects of different protein content and glycaemic index of ad libitum diets on diabetes risk factors in overweight adults: the DIOGenes multicentre, randomized, dietary intervention trial

BACKGROUND

Dietary regimens providing different levels of protein and glycemic index (GI) foods when prescribed for weight management may also influence insulin sensitivity.

PROCEDURES AND OUTCOMES

Overweight/obese adults in 8 European countries who lost ≥ 8% of initial body-weight (BW) after following a low calorie diet (LCD) were later randomly assigned with a 2x2 factorial design into 4 ad libitum dietary groups with two different protein content levels and dissimilar glycemic index, which were compared to a healthy reference diet. Specific markers assessing insulin resistance were measured. The LCD was initially applied to 932 adults and 773 were randomised to the 5 ad libitum diets. The 6-months programme was completed by 548 participants. The assignment to the Low Protein /High Glycemic Index diet induced a statistically higher HOMA-IR increase during the 6 months period as compared to the control. Contrariwise, the insulin response was lower in the High Protein/Low Glycemic Index diet after 60 and 90 min of an Oral Glucose Tolerance test subsequently carried out after the 6-months intervention. The Low Glycemic Index diets (either with high or low protein content) also lead to a decrease in fructosamine levels during the trial.

CONCLUSION/INTERPRETATION

After a weight loss period, an increase in the dietary protein proportions and a decrease in the consumption of foods with a high Glycemic Index within an ad libitum dietary intervention aiming to weight maintenance produced favorable effects on glycaemic control and insulin sensitivity in overweight/obese subjects.

Chronologically scheduled snacking with high-protein products within the habitual diet in type-2 diabetes patients leads to a fat mass loss: a longitudinal study

BACKGROUND

Obesity is the most relevant overnutrition disease worldwide and is associated to different metabolic disorders such as insulin resistance and type-2 diabetes. Low glycemic load foods and diets and moderately high protein intake have been shown to reduce body weight and fat mass, exerting also beneficial effects on LDL-cholesterol, triglyceride concentrations, postprandial glucose curve and HDL-cholesterol levels. The present study aimed at studying the potential functionality of a series of low glycemic index products with moderately high protein content, as possible coadjuvants in the control of type-2 diabetes and weight management following a chronologically planned snacking offer (morning and afternoon).

METHODS

The current trial followed a single group, sequential, longitudinal design, with two consecutive periods of 4 weeks each. A total of 17 volunteers participated in the study. The first period was a free living period, with volunteers' habitual ad libitum dietary pattern, while the second period was a free-living period with structured meal replacements at breakfast, morning snack and afternoon snack, which were exchanged by specific products with moderately high protein content and controlled low glycemic index, following a scheduled temporal consumption. Blood extractions were performed at the beginning and at the end of each period (free-living and intervention). Parameters analysed were: fasting glucose, insulin, glycosylated hemoglobin, total-, HDL- and LDL-cholesterol, triglyceride, C - reactive protein and Homocysteine concentrations. Postprandial glucose and insulin were also measured. Anthropometrical parameters were monitored each 2 weeks during the whole study.

RESULTS

A modest but significant (p = 0.002) reduction on body weight (1 kg) was observed during the intervention period, mainly due to the fat mass loss (0.8 kg, p = 0.02). This weight reduction was observed without apparently associated changes in total energy intake. None of the biochemical biomarkers measured was altered throughout the whole study.

CONCLUSIONS

Small changes in the habitual dietary recommendations in type-2 diabetes patients by the inclusion of specific low-glycemic, moderately high-protein products in breakfast, morning and afternoon snacks may promote body weight and fat-mass loss, without apparently altering biochemical parameters and cardiovascular risk-related factors.

TRIAL REGISTRATION

Trial registered at clinicaltrials.gov NCT01264523.

Weight regain after a diet-induced loss is predicted by higher baseline leptin and lower ghrelin plasma levels

CONTEXT

Appetite-related hormones may play an important role in weight regain after obesity therapy.

OBJECTIVE

Our objective was to investigate the potential involvement of ghrelin, leptin, and insulin plasma levels in weight regain after a therapeutic hypocaloric diet.

DESIGN

A group of obese/overweight volunteers (49 women and 55 men; 35 ± 7 yr; 30.7 ± 2.4 kg/m(2)) followed an 8-wk hypocaloric diet (-30% energy expenditure) and were evaluated again 32 wk after treatment. Body weight as well as plasma fasting ghrelin, leptin, and insulin concentrations were measured at three points (wk 0, 8, and 32).

RESULTS

After the 8-wk hypocaloric diet, the average weight loss was -5.0 ± 2.2% (P < 0.001). Plasma leptin and insulin concentrations decreased significantly, whereas ghrelin levels did not markedly change. In the group regaining more than 10% of the weight loss, leptin levels were higher (P < 0.01), whereas ghrelin levels were lower (P < 0.05). No differences were observed in insulin levels. Weight regain at wk 32 was negatively correlated with ghrelin and positively associated with leptin levels at baseline (wk 0) and endpoint (wk 8). These outcomes showed a gender-specific influence, being statistically significant among men for ghrelin and between women for leptin. Moreover, a decrease in ghrelin after an 8-wk hypocaloric diet was related to an increased risk for weight regain (odds ratio = 3.109; P = 0.008) whereas a greater reduction in leptin (odds ratio = 0.141; P = 0.001) was related to weight-loss maintenance.

CONCLUSIONS

Subjects with higher plasma leptin and lower ghrelin levels at baseline could be more prone to regain lost weight, and hormones levels could be proposed as biomarkers for predicting obesity-treatment outcomes.

Weight gain induced by an isocaloric pair-fed high fat diet: a nutriepigenetic study on FASN and NDUFB6 gene promoters

Experimental studies have demonstrated that dietary macronutrient distribution plays an important role in insulin regulation, a risk factor associated to obesity, diabetes and other metabolic disorders. To assess whether the macronutrient composition of the diet could be related to obesity onset by affecting the epigenetic regulation of gene expression, we investigated in rats the metabolic effects of two pair-fed isocaloric diets: control (rich in carbohydrates) and high fat diet (rich in fat; HFD). Compared to controls, HFD induced higher weight gain and adiposity and impaired glucose tolerance, which was accompanied by a slight increase in adiponectin levels and liver steatosis. Epididymal adipose tissue expression of the fatty acid synthase (FASN) gene and NADH dehydrogenase (ubiquinone) 1β-subcomplex 6 (NDUFB6) were significantly reduced in HFD group. These variations in mRNA levels were accompanied by changes in the methylation patterns of several CpG islands located in the promoter region of these genes. However, no correlations were found between gene expression and the methylation status. These results suggest that high fat intake produces overweighted rats independently of total energy intake. These diets could also induce some epigenetic changes in the promoters of key genes that could influence gene expression and may be behind metabolic alterations.

Obesity and the metabolic syndrome: role of different dietary macronutrient distribution patterns and specific nutritional components on weight loss and maintenance

Weight loss and subsequent body weight maintenance are difficult for obese individuals despite the wide variety of dietary regimens and approaches. A substantial body of scientific evidence has shown that by simply varying the macronutrient distribution and composition of dietary factors, weight losses of varying amounts, longer-term body weight maintenance periods, better appetite regulation, and changes in features of the metabolic syndrome can be achieved. At present, renewed efforts are underway to increase the protein content of weight-loss diets, simultaneously restrict fat consumption to no more than 30%, favor polyunsaturated fat, have carbohydrates account for between 40 and 50% of total energy intake, and promote the consumption of low-glycemic foods. The present article reviews the scientific evidence for the effects of several dietary manipulations and sustainable strategies for weight loss and body weight stability as well as for treating specific features of the metabolic syndrome.

Session 4: CVD, diabetes and cancer Diet, insulin resistance and diabetes: the right (pro)portions

Excess energy intake and positive energy balance are associated with the development of obesity and insulin resistance, which is a key feature underlying the pathophysiology of type 2 diabetes. It is possible that dietary macronutrient intake may also be important, in particular increased levels of sugar and fat. High-fat energy-dense diets contribute to energy excess and obesity. Fat type is also a factor, with evidence suggesting that saturated fat intake is linked to insulin resistance. However, controversy exists about the role of carbohydrate in the development of diabetes. Epidemiological studies suggest that the risk of diabetes is unrelated to the total amount of carbohydrate, but that fibre intake and glycaemic load are important. Common dietary advice for the prevention of diabetes often advocates complex carbohydrates and restriction of simple carbohydrates; however, sugars may not be the main contributor to glycaemic load. Evidence continues to emerge in relation to the influence of dietary sugars intake on insulin resistance. In broader dietary terms fruit and vegetable intake may influence insulin resistance, possibly related to increased intake of fibre and micronutrients or displacement of other food types. There is also considerable debate about the most effective diet and appropriate macronutrient composition to facilitate weight loss. Recent evidence suggests comparable effects of diets with varying macronutrient profiles on weight loss, which is predominantly related to energy restriction. However, based on the results of diabetes prevention trials focusing on lifestyle measures, evidence favours low-fat diets as the preferred approach for weight loss and diabetes prevention.

Daily physical activity and macronutrient distribution of low-calorie diets jointly affect body fat reduction in obese women

Inadequate dietary patterns and sedentary lifestyles are believed to be important factors in predisposing people to obesity. This study analyzed the potential interaction between habitual physical activity and the carbohydrate (CHO)-fat distribution in 2 hypocaloric diets and the impact of such interplay on body composition changes. Forty healthy obese women, 20–50 years old, were randomly assigned to a high- or low-CHO energy-restricted diet, which was low or high in fat, respectively, during 10 weeks. Baseline and final measurements were performed to assess dietary habits, resting metabolic rate, and body composition changes. Physical activity was measured with a triaxial accelerometer and with a questionnaire. There were no significant differences in anthropometric and metabolic variables between both dietary groups at baseline. However, there was a positive correlation between total free-living physical activity and arm muscle preservation after 10 weeks (r = 0.371; p = 0.024). Interestingly, an interaction between macronutrient (CHO–fat distribution) intake and physical activity was found, since less-active subjects with a high-CHO–low-fat diet showed a greater fat loss than those more active with a lower-CHO–high-fat diet, whereas more-active subjects with a high-CHO–low-fat diet showed a smaller fat loss than those receiving a low-CHO–high-fat diet. Physical activity and the macronutrient content of energy-restricted diets, when designed to promote body fat mass reduction, should be considered together to better predict the outcome.

Effects of two energy-restricted diets differing in the carbohydrate/protein ratio on weight loss and oxidative changes of obese men

INTRODUCTION

Low-carbohydrate, high-protein diets are a current challenge in the nutritional treatment of obesity.

OBJECTIVE

To compare the effect of a low-carbohydrate high-protein diet with a traditional hypocaloric diet on weight loss and mitochondrial oxidative metabolism.

SUBJECTS AND METHODS

Nineteen obese men (age 36+/-6 years; body mass index 34+/-2 kg/m2) were randomized to follow one of the two diets-control diet (15% protein; 30% lipids; 55% carbohydrates) or high-protein diet (30% protein; 30% lipids; 40% carbohydrates)-over an 8-week period. Anthropometry, biochemical variables, resting energy expenditure and mitochondrial oxidation were measured at the start and at the end of the intervention.

RESULTS

The high-protein diet produced a greater weight loss (-8.3+/-1.2% versus -5.5+/-2.5%, P = 0.012) than the control diet. Interestingly, an activation in the mitochondrial oxidation was found in the high-protein-fed group. This stimulation was positively correlated with the final resting energy expenditure and negatively associated with the final fat mass content.

CONCLUSION

Low-carbohydrate high-protein diets could involve specific changes in mitochondrial oxidation that could be related to a higher 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.

Metabolic effects of low glycaemic index diets

The persistence of an epidemic of obesity and type 2 diabetes suggests that new nutritional strategies are needed if the epidemic is to be overcome. A promising nutritional approach suggested by this thematic review is metabolic effect of low glycaemic-index diet. The currently available scientific literature shows that low glycaemic-index diets acutely induce a number of favorable effects, such as a rapid weight loss, decrease of fasting glucose and insulin levels, reduction of circulating triglyceride levels and improvement of blood pressure. The long-term effect of the combination of these changes is at present not known. Based on associations between these metabolic parameters and risk of cardiovascular disease, further controlled studies on low-GI diet and metabolic disease are needed.

Effect of diet on the low-grade and chronic inflammation associated with obesity and metabolic syndrome

Adipose tissue is an active endocrine and paracrine organ that releases a large number of cytokines and biomarkers, which are involved in the development of chronic diseases. These effects have been attributed to direct or indirect mechanisms acting on insulin resistance, inflammation and endothelial dysfunction. In addition, the expression and secretion of these biomarkers in various tissues can be influenced by dietary patterns, with an effect on inflammatory status. In this context, following an energy-balanced diet, moderate in carbohydrates, high in oleic and omega-3 fatty acids, and low in saturated and trans fatty acids, with high intake of fruits and legumes and moderate alcohol consumption, appears to have beneficial effects on the inflammatory state associated with obesity and the manifestations of metabolic syndrome. However, the long-term impact of habitual intake and the mechanisms involved in distinct physiological and pathological conditions remain unclear.

Enhanced short-term improvement of insulin response to a low-caloric diet in obese carriers the Gly482Ser variant of the PGC-1alpha gene

AIM

The Gly482Ser missense mutation of the transcriptional coactivator, peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha) has been involved in insulin function impairments, with conflicting results. The current study investigated the relationships of carrying this polymorphism with insulin resistance (IR) during a short-term weight-loss and the subsequent weight follow-up.

METHODS

The Gly482Ser was genotyped in 180 Spanish volunteers [body mass index: 31.4+/-3.2kg/m(2); age: 35+/-5 years]. Specific phenotypical measurements were determined at baseline, following an 8-week low-calorie diet (LCD) as well as after 6-month and 1-year of follow-up.

RESULTS

At baseline the Ser482Ser genotype was associated with higher HOMA-IR and insulin concentrations than the other genotypes (p<0.05), which was accompanied by an increased higher risk of IR (OR: 2.97; 95% CI: 1.24-7.15). After following the LCD, such increased risk of insulin insensitivity in Ser482Ser carriers was toned down (p>0.05). This outcome was sustained after 6-month and 1-year of follow-up (p>0.05).

CONCLUSIONS

These data show an increased risk of IR in obese carrying the rs8192673 Ser482Ser genotype. This risk was markedly reduced by an energy-restricted diet, which was sustained 6 months and 1 year after the diet therapy. This observation allows identifying obese subjects who might personally profit most from an energy-restrictive treatment concerning insulin response and lead to more individualized prognostic and therapeutic decisions.

Sirtuin gene expression in human mononuclear cells is modulated by caloric restriction

BACKGROUND

Sirtuins may provide novel targets for treating some diseases associated with oxidative stress, such as obesity and its comorbidities. However, there are a few in vivo studies in humans about the potential role of sirtuins as therapeutic targets among obese patients undergoing caloric restriction. Therefore, the aim of this study was to assess if the gene expression of sirtuins is modulated in peripheral blood mononuclear cells (PBMC) by a hypocaloric diet devised to lose weight in humans.

MATERIALS AND METHODS

Gene expression of two sirtuins (SIRT1 and SIRT2) in the PBMC of obese subjects (32.3 +/- 5.5 kg m(-2)) before and following an 8-week hypocaloric diet was investigated. NADH-coenzyme Q reductase (NDUFS2) and cytochrome c oxidase assembly protein (COX15) gene expression was selected together with plasma antioxidant power and nitric oxide as markers of antioxidant status. A quantitative real-time polymerase chain reaction approach was performed to assess the nutrigenomics outcome. Moreover, 2-keto[1-(13)C]isocaproate breath test (KICA-BT) parameters were evaluated to study mitochondrial oxidation in vivo.

RESULTS

The intervention up-regulated the expression of both sirtuins, being inversely associated with total antioxidant capacity and directly related to nitric oxide, mitochondrial oxidation assessed by the KICA-BT and the expression of the mitochondrial proteins COX15 and NDUFS2.

CONCLUSION

SIRT1 and SIRT2 may serve as key regulators for some obesity comorbidities related to antioxidant status, while PBMC could be a model to study the effect of the sirtuin response in obesity therapy.

A diet rich in long chain omega-3 fatty acids modulates satiety in overweight and obese volunteers during weight loss

Long chain omega-3 fatty acids (LC n-3 FA) are considered nutritional factors with a potential to modulate food intake. Thus, the aim of the current study was to determine whether appetite could be affected by LC n-3 FA when included in a calorie-restricted diet to treat overweight or obesity. Appetite was explored in volunteers (31+/-5 years; BMI: 28.3+/-1.5 kg/m(2)) during the last 2 weeks of an 8-week energy-restricted balanced diet (weight loss=-5.9+/-3.1%) providing either a low (<260 mg/day; n=112) or a high amount (>1300 mg/day; n=121) of LC n-3 FA. Erythrocyte membrane fatty acids were measured to detect diet-related changes in fatty acids and a validated visual analogue scale (VAS) was used to measure hunger sensations directly after and 2h after a test dinner. The LC n-3 FA content in erythrocyte membrane was lower in the low LC n-3 FA group (10.5+/-2.5% vs. 12.5+/-2.6%; p<0.001) after the intervention. The VAS assessment revealed lower hunger sensations in the high LC n-3 FA group immediately after the test dinner (fullness: p=0.045) and after 120 min (fullness: p=0.008; hunger: p=0.039). Correlation analysis showed a positive relation between n-3 FA/n-6 FA ratio in erythrocyte membrane and fullness 2h postprandial (r=0.139; p=0.032). In conclusion, LC n-3 FA intake modulates postprandial satiety in overweight and obese volunteers during weight loss. Further research is needed to investigate whether LC n-3 FA improve compliance to the nutritional treatment of overweight and obesity as well as weight loss maintenance.

Popular weight-loss diets: from evidence to practice

The increasing number of overweight and obese individuals has become one of the leading public health concerns in many countries around the world. Concomitant with this increase in the prevalence of obesity has been the rise in the number of weight-loss diets, many of which alter macronutrient composition, but with the majority focused on carbohydrate restriction. Low-carbohydrate diets are attractive because they promise rapid weight loss without having to count calories and compromise the consumption of many palatable foods. By contrast, traditional dietary recommendations for weight loss endorse a fat-restricted and calorie-restricted diet high in complex carbohydrates. Evidence indicates that low-carbohydrate diets could be better in terms of short-term weight loss relative to traditional low-fat diets, but little is known about their long-term utility and safety. Diets based on the traditional Mediterranean dietary pattern are becoming increasingly popular because of their healthful benefits, particularly regarding cardiovascular outcomes. Mediterranean diets encourage consumption of a variety of palatable foods, optimizing adherence and sustainability. In this Review we discuss the current evidence on the efficacy of low-fat, low-carbohydrate and Mediterranean dietary patterns for weight loss, their potential mechanisms of action and important clinical considerations.