A very-low-calorie ketogenic diet normalises obesity-related enhanced levels of erythropoietin compared with a low-calorie diet or bariatric surgery.

PURPOSE: Nutritional ketosis synergistically with body-weight loss induced by a very-low-calorie ketogenic diet (VLCKD) has proven to be effective in improving obesity-related pathophysiology. Recently, growing attention has been focused on the relation between erythropoietin (EPO) and obesity. Thus, this study aims to investigate whether nutritional ketosis and weight loss induced by a VLCKD modify the circulating levels of EPO in patients with obesity in comparison with the effect of low-calorie diet (LCD) or bariatric surgery (BS). METHODS: EPO levels, iron status and body composition parameters were evaluated in 72 patients with overweight or obesity and 27 normal-weight subjects at baseline and after the three different weight-reduction therapies (VLCKD, LCD and BS) in 69 patients with excess body weight. ß-hydroxybutyrate levels were also measured in the VLCKD group. The follow-up was established at 2-3 months and 4-6 months. RESULTS: It was found that EPO levels were higher in morbid obesity and correlated with higher basal weight, fat mass (FM) and fat-free mass (FFM) in the overall sample. High baseline EPO levels were also correlated with higher impact on the course of weight loss and changes in FM and FFM induced by the three weight-loss interventions. Furthermore, the VLCKD induced a decrease in EPO levels coinciding with maximum ketosis, which was maintained over time, while statistically significant changes were not observed after LCD and BS. CONCLUSION: The obesity-related increased EPO levels are restored after VLCKD intervention at the time of maximum ketosis, suggesting a potential role of the nutritional ketosis induced by the VLCKD. Baseline EPO levels could be a biomarker of response to a weight-loss therapy.

DNA methylation pattern changes following a short-term hypocaloric diet in women with obesity.

BACKGROUND/OBJECTIVES: We aimed to investigate the effects of short-term hypocaloric diet-induced weight loss on DNA methylation profile in leukocytes from women with severe obesity. METHODS: Eleven women with morbid obesity (age: 36.9 ± 10.3 years; BMI: 58.5 ± 10.5 kg/m2) were assessed before and after 6 weeks of a hypocaloric dietary intervention. The participants were compared with women of average weight and the same age (age: 36.9 ± 11.8 years; BMI: 22.5 ± 1.6 kg/m2). Genome-wide DNA methylation analysis was performed in DNA extracted from peripheral blood leukocytes using the Infinium Human Methylation 450 BeadChip assay. Changes (Δß) in the methylation level of each CpGs were calculated. A threshold with a minimum value of 10%, p < 0.001, for the significant CpG sites based on Δß and a false discovery rate of <0.05 was set. RESULTS: Dietary intervention changed the methylation levels at 16,064 CpG sites. These CpGs sites were related to cancer, cell cycle-related, MAPK, Rap1, and Ras signaling pathways. However, regardless of hypocaloric intervention, a group of 878 CpGs (related to 649 genes) remained significantly altered in obese women when compared with normal-weight women. Pathway enrichment analysis identified genes related to the cadherin and Wnt pathway, angiogenesis signaling, and p53 pathways by glucose deprivation. CONCLUSION: A short-term hypocaloric intervention in patients with severe obesity partially restored the obesity-related DNA methylation pattern. Thus, the full change of obesity-related DNA methylation patterns could be proportional to the weight-loss rate in these patients after dietary interventions.

Altered pathways in methylome and transcriptome longitudinal analysis of normal weight and bariatric surgery women.

DNA methylation could provide a link between environmental, genetic factors and weight control and can modify gene expression pattern. This study aimed to identify genes, which are differentially expressed and methylated depending on adiposity state by evaluating normal weight women and obese women before and after bariatric surgery (BS). We enrolled 24 normal weight (BMI: 22.5 ± 1.6 kg/m2) and 24 obese women (BMI: 43.3 ± 5.7 kg/m2) submitted to BS. Genome-wide methylation analysis was conducted using Infinium Human Methylation 450 BeadChip (threshold for significant CpG sites based on delta methylation level with a minimum value of 5%, a false discovery rate correction (FDR) of q < 0.05 was applied). Expression levels were measured using HumanHT-12v4 Expression BeadChip (cutoff of p ≤ 0.05 and fold change ≥2.0 was used to detect differentially expressed probes). The integrative analysis of both array data identified four genes (i.e. TPP2, PSMG6, ARL6IP1 and FAM49B) with higher methylation and lower expression level in pre-surgery women compared to normal weight women: and two genes (i.e. ZFP36L1 and USP32) that were differentially methylated after BS. These methylation changes were in promoter region and gene body. All genes are related to MAPK cascade, NIK/NF-kappaB signaling, cellular response to insulin stimulus, proteolysis and others. Integrating analysis of DNA methylation and gene expression evidenced that there is a set of genes relevant to obesity that changed after BS. A gene ontology analysis showed that these genes were enriched in biological functions related to adipogenesis, orexigenic, oxidative stress and insulin metabolism pathways. Also, our results suggest that although methylation plays a role in gene silencing, the majority of effects were not correlated.

DNA methylation screening after roux-en Y gastric bypass reveals the epigenetic signature stems from genes related to the surgery per se.

BACKGROUND/OBJECTIVES: Obesity has been associated with gene methylation regulation. Recent studies have shown that epigenetic signature plays a role in metabolic homeostasis after Roux-en Y gastric bypass (RYGB). To conduct a genome-wide epigenetic analysis in peripheral blood to investigate whether epigenetic changes following RYGB stem from weight loss or the surgical procedure per se. SUBJECTS/METHODS: By means of the Infinium Human Methylation 450 BeadChip array, global methylation was analyzed in blood of 24 severely obese women before and 6 months after RYGB and in 24 normal-weight women (controls). RESULTS: In blood cells, nine DMCpG sites showed low methylation levels before surgery, methylation levels increased after RYGB and neared the levels measured in the controls. Additionally, 44 CpG sites associated with the Wnt and p53 signaling pathways were always differently methylated in the severely obese patients as compared to the controls and were not influenced by RYGB. Finally, 1638 CpG sites related to inflammation, angiogenesis, and apoptosis presented distinct methylation in the post-surgery patients as compared to the controls. CONCLUSION: Bariatric surgery per se acts on CpGs related to inflammation, angiogenesis, and endothelin-signaling. However, the gene cluster associated with obesity remains unchanged, suggesting that weight loss 6 months after RYGB surgery cannot promote this effect.

Circadian gene methylation profiles are associated with obesity, metabolic disturbances and carbohydrate intake.

The circadian clock regulates the daily rhythms of several physiological and behavioral processes. Disruptions in clock genes have been associated with obesity and related comorbidities. This study aimed to analyze the association of DNA methylation signatures at circadian rhythm pathway genes with body mass index (BMI), metabolic profiles and dietary intakes. DNA methylation profiling was determined by microarray in white blood cells from 474 adults from the Methyl Epigenome Network Association (MENA) project. Kyoto Encyclopedia of Genes and Genomes database was used to identify the genes integrating the circadian rhythm pathway. Network enrichment analyses were performed with the PathDIP platform. Associations between circadian methylation patterns with anthropometric measurements, the metabolic profile, clinical data and dietary intakes were analyzed. DNA methylation patterns of nine CpG sites at six circadian rhythm pathway genes were strongly correlated with BMI (false discovery rates <0.0001). These CpGs encompassed cg09578018 (RORA), cg20406576 (PRKAG2), cg10059324 (PER3), cg01180628 (BHLHE40), cg23871860 (FBXL3), cg16964728 (RORA), cg14129040 (CREB1), cg07012178 (PRKAG2) and cg24061580 (PRKAG2). Interestingly, network enrichment analyses revealed that the six BMI-associated genes statistically contributed to the regulation of the circadian rhythm pathway (p = 1.9E-10). In addition, methylation signatures at cg09578018 (RORA), cg24061580 (PRKAG2), cg01180628 (BHLHE40) and cg10059324 (PER3) also correlated with insulin resistance (p < 0.0001) and mean arterial blood pressure (p < 0.0001). Furthermore, relevant correlations (p < 0.05) between methylation at cg09578018 (RORA) and cg01180628 (BHLHE40) with total energy and carbohydrate intakes were found. This investigation revealed potential associations of DNA methylation profiles at circadian genes with obesity, metabolic disturbances and carbohydrate intake, with potential impact on weight homeostasis.

Plasma FGF21 levels in obese patients undergoing energy-restricted diets or bariatric surgery: a marker of metabolic stress?

BACKGROUND: Fibroblast growth factor 21 (FGF21) has been suggested to be an endocrine signal of nutritional status and an active regulator of metabolism. However, there is no agreement on the effect of weight-loss therapies on circulating levels of FGF21 in humans. OBJECTIVE: To assess FGF21 circulating levels in adiposity excess and after different weight-loss strategies prescribed in five different groups from four independent centers. SUBJECTS AND METHODS: Body composition, ketosis, insulin sensitivity and FGF21 were evaluated in 181 excess body weight and 14 normal-weight subjects. From the excess body weight patients, two independent groups (discovery cohort; n=20 and validation cohort; n=28) undertook a very low-calorie ketogenic (VLCK) diet, a third group followed a low-calorie (LC) diet (n=84) and other two groups underwent bariatric surgery (discovery cohort; n=24 and validation cohort; n=25). The follow-up was 4 to 6 or 12 months, respectively. RESULTS: FGF21 levels were higher in excess body weight patients than in normal-weight subjects. The energy-restriction therapy to lose weight induced a significant decrease, with respect to baseline, in circulating levels of FGF21 (VLCK: -62.5 pg ml-1 or -14.8 pg ml-1 and LC diet: -67.9 pg ml-1). There were no differences in FGF21 levels between both energy-restriction treatments. On the contrary, after bariatric surgery morbidly obese patients showed a significant increase in FGF21, especially 1 month after surgery (148.8 pg ml-1 higher than baseline). The FGF21 differential changes occur concomitantly with a non-induced ketosis situation (0.66±0.56 mm) in bariatric surgery, and an improvement in adiposity and insulin sensitivity induced by the three therapies. CONCLUSIONS: FGF21 levels were reduced after energy-restricted treatments and severely increased after bariatric surgery, independently of the weight reduction magnitude, insulin sensitivity or ketosis. Therefore, FGF21 appears to be a marker of severe nutritional stress.

DNA methylation map in circulating leukocytes mirrors subcutaneous adipose tissue methylation pattern: a genome-wide analysis from non-obese and obese patients.

The characterization of the epigenetic changes within the obesity-related adipose tissue will provide new insights to understand this metabolic disorder, but adipose tissue is not easy to sample in population-based studies. We aimed to evaluate the capacity of circulating leukocytes to reflect the adipose tissue-specific DNA methylation status of obesity susceptibility. DNA samples isolated from subcutaneous adipose tissue and circulating leukocytes were hybridized in the Infinium HumanMethylation 450 BeadChip. Data were compared between samples from obese (n = 45) and non-obese (n = 8-10) patients by Wilcoxon-rank test, unadjusted for cell type distributions. A global hypomethylation of the differentially methylated CpG sites (DMCpGs) was observed in the obese subcutaneous adipose tissue and leukocytes. The overlap analysis yielded a number of genes mapped by the common DMCpGs that were identified to reflect the obesity state in the leukocytes. Specifically, the methylation levels of FGFRL1, NCAPH2, PNKD and SMAD3 exhibited excellent and statistically significant efficiencies in the discrimination of obesity from non-obesity status (AUC > 0.80; p < 0.05) and a great correlation between both tissues. Therefore, the current study provided new and valuable DNA methylation biomarkers of obesity-related adipose tissue pathogenesis through peripheral blood analysis, an easily accessible and minimally invasive biological material instead of adipose tissue.

Short-term safety, tolerability and efficacy of a very low-calorie-ketogenic diet interventional weight loss program versus hypocaloric diet in patients with type 2 diabetes mellitus.

UNLABELLED: Brackground:The safety and tolerability of very low-calorie-ketogenic (VLCK) diets are a current concern in the treatment of obese type 2 diabetes mellitus (T2DM) patients. OBJECTIVE: Evaluating the short-term safety and tolerability of a VLCK diet (<50 g of carbohydrate daily) in an interventional weight loss program including lifestyle and behavioral modification support (Diaprokal Method) in subjects with T2DM. METHODS: Eighty-nine men and women, aged between 30 and 65 years, with T2DM and body mass index between 30 and 35 kg m(-)(2) participated in this prospective, open-label, multi-centric randomized clinical trial with a duration of 4 months. Forty-five subjects were randomly assigned to the interventional weight loss (VLCK diet), and 44 to the standard low-calorie diet. RESULTS: No significant differences in the laboratory safety parameters were found between the two study groups. Changes in the urine albumin-to-creatinine ratio in VLCK diet were not significant and were comparable to control group. Creatinine and blood urea nitrogen did not change significantly relative to baseline nor between groups. Weight loss and reduction in waist circumference in the VLCK diet group were significantly larger than in control subjects (both P<0.001). The decline in HbA1c and glycemic control was larger in the VLCK diet group (P<0.05). No serious adverse events were reported and mild AE in the VLCK diet group declined at last follow-up. CONCLUSIONS: The interventional weight loss program based on a VLCK diet is most effective in reducing body weight and improvement of glycemic control than a standard hypocaloric diet with safety and good tolerance for T2DM patients.

Modulation of Irisin and Physical Activity on Executive Functions in Obesity and Morbid obesity.

Whether the executive profile is different between obesity (OB) and morbid obesity (MO) remains unclear. Recent evidence suggests that physical activity (PA) can act as a cognitive enhancer. Irisin is a recently discovered hormone associated with some of the positive effects of PA. The objective of the study was to investigate the executive profile in OB and MO, and to explore the role of PA and irisin. 114 participants were included (21 OB, 44 MO and 49 healthy controls-HC) in the study and assessed with the Wisconsin Card Sorting Test, Stroop Color and Word Test, and Iowa Gambling Task. All participants were female, aged between 18 and 60 years. Results showed a similar dysfunctional profile on decision making in OB and MO compared with HC. Thus, no specific neuropsychological profiles between OB and MO can be clearly observed in our sample. However, a negative correlation was found between irisin and executive functioning. These results demonstrate a specific executive profile in OB and a relevant and negative modulation of irisin on executive functioning. Although irisin might be a promising target for the treatment of obesity, its effects on cognition might be considered when thinking about its therapeutic use.

Genome-wide DNA methylation pattern in visceral adipose tissue differentiates insulin-resistant from insulin-sensitive obese subjects.

Elucidating the potential mechanisms involved in the detrimental effect of excess body weight on insulin action is an important priority in counteracting obesity-associated diseases. The present study aimed to disentangle the epigenetic basis of insulin resistance by performing a genome-wide epigenetic analysis in visceral adipose tissue (VAT) from morbidly obese patients depending on the insulin sensitivity evaluated by the clamp technique. The global human methylome screening performed in VAT from 7 insulin-resistant (IR) and 5 insulin-sensitive (IS) morbidly obese patients (discovery cohort) analyzed using the Infinium HumanMethylation450 BeadChip array identified 982 CpG sites able to perfectly separate the IR and IS samples. The identified sites represented 538 unique genes, 10% of which were diabetes-associated genes. The current work identified novel IR-related genes epigenetically regulated in VAT, such as COL9A1, COL11A2, CD44, MUC4, ADAM2, IGF2BP1, GATA4, TET1, ZNF714, ADCY9, TBX5, and HDACM. The gene with the largest methylation fold-change and mapped by 5 differentially methylated CpG sites located in island/shore and promoter region was ZNF714. This gene presented lower methylation levels in IR than in IS patients in association with increased transcription levels, as further reflected in a validation cohort (n = 24; 11 IR and 13 IS). This study reveals, for the first time, a potential epigenetic regulation involved in the dysregulation of VAT that could predispose patients to insulin resistance and future type 2 diabetes in morbid obesity, providing a potential therapeutic target and biomarkers for counteracting this process.

A role for novel adipose tissue-secreted factors in obesity-related carcinogenesis.

Obesity, a pandemic disease, is caused by an excessive accumulation of fat that can have detrimental effects on health. Adipose tissue plays a very important endocrine role, secreting different molecules that affect body physiology. In obesity, this function is altered, leading to a dysfunctional production of several factors, known as adipocytokines. This process has been linked to various comorbidities associated with obesity, such as carcinogenesis. In fact, several classical adipocytokines with increased levels in obesity have been demonstrated to exert a pro-carcinogenic role, including leptin, TNF-α, IL-6 and resistin, whereas others like adiponectin, with decreased levels in obesity, might have an anti-carcinogenic function. In this expanding field, new proteomic techniques and approaches have allowed the identification of novel adipocytokines, a number of which exhibit an altered production in obesity and type 2 diabetes and thus are related to adiposity. Many of these novel adipocytokines have also been identified in various tumour types, such as that of the breast, liver or endometrium, thereby increasing the list of potential contributors to carcinogenesis. This review is focused on the regulation of these novel adipocytokines by obesity, including apelin, endotrophin, FABP4, lipocalin 2, omentin-1, visfatin, chemerin, ANGPTL2 or osteopontin, emphasizing its involvement in tumorigenesis.

Interplay of atherogenic factors, protein intake and betatrophin levels in obese-metabolic syndrome patients treated with hypocaloric diets.

CONTEXT: The understanding of the potential role of betatrophin in human metabolic disorders is a current challenge. OBJECTIVE: The present research evaluated circulating betatrophin levels in obese patients with metabolic syndrome (MetSyn) features under energy-restricted weight-loss programs and in normal weight in order to establish the putative interplay between the levels of this hormone, diet and metabolic risk factors linked to obesity and associated comorbidities. SUBJECTS AND METHODS: One hundred forty-three participants were enrolled in the study (95 obese-MetSyn; age 49.5±9.4 years; body mass index (BMI) 35.7±4.5 kg m(-2) and 48 normal weight; age 35.71±8.8 years; BMI 22.9±2.2 kg m(-2)). A nutritional therapy consisting in two hypocaloric strategies (control diet based on the AHA recommendations and the RESMENA (MEtabolic Syndrome REduction in Navarra) diet, a novel dietary program with changes in the macronutrient distribution) was only prescribed to obese-MetSyn participants who were randomly allocated to the dietary strategies. Dietary records, anthropometrical and biochemical variables as well as betatrophin levels were analyzed before (pre-intervention, week 0), at 8 weeks (post-intervention, week 8) and after 4 additional months of self-control period (follow-up, week 24). RESULTS: Betatrophin levels were higher in obese-MetSyn patients than normal-weight subjects (1.24±0.43 vs 0.97±0.69 ng ml(-1), respectively, P=0.012), and levels were positively associated with body composition, metabolic parameters, leptin and irisin in all participants at baseline. Notably, low pre-intervention (week 0) betatrophin levels in obese patients were significantly associated with higher dietary-induced changes in atherogenic risk factors after 8 weeks. Moreover, protein intake, especially proteins from animal sources, was an independent determinant of betatrophin levels after dietary treatment (B=-0.27; P=0.012). CONCLUSIONS: Betatrophin is elevated in obese patients with MetSyn features and is associated with poorer nutritional outcomes of adiposity and dyslipidemia traits after a weight-loss program. Dietary protein intake could be a relevant modulator of betatrophin secretion and activity.

Secreted factors derived from obese visceral adipose tissue regulate the expression of breast malignant transformation genes.

BACKGROUND/OBJECTIVES: Obese adipose tissue, especially the visceral depot, exhibits altered production of several molecules that could have a role on the initiation/promotion of breast cancer development. The aim of this work was to evaluate the effect of excess adipose tissue and its secreted factors on the expression of genes involved in the early steps of tumor promotion on the mammary gland. SUBJECTS AND METHODS: Carcinogenesis-related gene expression was evaluated in mammary gland tissue from female diet-induced obese (DIO) Sprague-Dawley rats and circulating leukocytes isolated from a group of breast cancer diagnosed and non-diagnosed obese women and compared with their normal weight counterparts. In addition, the human non-tumoral mammary epithelial cell line MCF10A was treated in vitro with the visceral (retroperitoneal adipose tissue (RPAT)) or subcutaneous adipose tissue (SAT) secretome and with rising concentrations of the lipid peroxidation by-product 4-hydroxynonenal (4-HNE). RESULTS: DIO rats were classified as susceptible to DIO (DIO-S) or partially resistant to DIO (DIO-R) according to the maximum fat mass gain of the lean group as a cut-off. As compared with lean and DIO-R, the DIO-S group showed a higher fat mass and lower lean mass. The anatomical characteristic of DIO-S was correlated with differential expression of cellular proliferation (ALDH3A1 and MYC) and antioxidant and DNA protection (GSTM2, SIRT1), and tumor suppression (TP53, PTEN, TGFB1) genes. Remarkably, this carcinogenesis-related gene expression pattern was reproduced in MCF10A treated with the RPAT secretome from DIO-S rats and with the lipid peroxidation by-product 4-HNE. Moreover, this pattern was also detected in leukocytes from obese women compared with normal weight women without evidence of breast cancer. CONCLUSIONS: Lipid peroxides secreted by the obese visceral adipose tissue could be among the relevant factors that promote changes involved in the early steps of tumor development in mammary gland. These changes can be detected even before histological alterations and in circulating leukocytes.

Genome-Wide DNA Methylation Analysis Identifies Novel Hypomethylated Non-Pericentromeric Genes with Potential Clinical Implications in ICF Syndrome.

INTRODUCTION AND RESULTS: Immunodeficiency, centromeric instability and facial anomalies syndrome (ICF) is a rare autosomal recessive disease, characterized by severe hypomethylation in pericentromeric regions of chromosomes (1, 16 and 9), marked immunodeficiency and facial anomalies. The majority of ICF patients present mutations in the DNMT3B gene, affecting the DNA methyltransferase activity of the protein. In the present study, we have used the Infinium 450K DNA methylation array to evaluate the methylation level of 450,000 CpGs in lymphoblastoid cell lines and untrasformed fibroblasts derived from ICF patients and healthy donors. Our results demonstrate that ICF-specific DNMT3B variants A603T/STP807ins and V699G/R54X cause global DNA hypomethylation compared to wild-type protein. We identified 181 novel differentially methylated positions (DMPs) including subtelomeric and intrachromosomic regions, outside the classical ICF-related pericentromeric hypomethylated positions. Interestingly, these sites were mainly located in intergenic regions and inside the CpG islands. Among the identified hypomethylated CpG-island associated genes, we confirmed the overexpression of three selected genes, BOLL, SYCP2 and NCRNA00221, in ICF compared to healthy controls, which are supposed to be expressed in germ line and silenced in somatic tissues. CONCLUSIONS: In conclusion, this study contributes in clarifying the direct relationship between DNA methylation defect and gene expression impairment in ICF syndrome, identifying novel direct target genes of DNMT3B. A high percentage of the DMPs are located in the subtelomeric regions, indicating a specific role of DNMT3B in methylating these chromosomal sites. Therefore, we provide further evidence that hypomethylation in specific non-pericentromeric regions of chromosomes might be involved in the molecular pathogenesis of ICF syndrome. The detection of DNA hypomethylation at BOLL, SYCP2 and NCRNA00221 may pave the way for the development of specific clinical biomarkers with the aim to facilitate the identification of ICF patients.

Irisin: 'fat' or artefact.

Soon after the discovery of the muscle-derived factor irisin, a great controversy arose in the literature regarding certain inconsistencies in the regulation of the fibronectin type III domain containing 5 protein (FNDC5/irisin) after exercise, as well as the unpredicted association of circulating irisin levels with parameters of adiposity in humans. Due to these questionable findings, doubts as to the identity of the soluble portion of FNDC5 as well as the real role of irisin and its possible therapeutic applications in the treatment of obesity and diabetes have proliferated. We recently postulated that FNDC5/irisin is an adipokine expressed and secreted by white adipose tissue in rats and humans. Its circulating concentration correlates with adiposity in humans among independent cohorts of patients. Further analysis, focused on obesity-related metabolic disorders, has shown that irisin could play a role in promoting insulin resistance or act as an adaptive response to counteract disturbances in glucose and lipid homoeostasis in obesity. Overall, this leads us to raise the question whether the new factor, increased in circulation of obese patients, is really irisin-reflecting fat mass or it is an artefact. Therefore, the current review is focused on the potential participation of adipose tissue in irisin circulating levels, and the role of irisin in metabolic pathologies associated with obesity in an attempt to clarify the controversy generated by these recently published reports.

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.

Higher baseline irisin concentrations are associated with greater reductions in glycemia and insulinemia after weight loss in obese subjects.

Irisin is assumed to be a relevant link between muscle and weight maintenance as well as to mediate exercise benefits on health. The aim of this study was to assess the possible associations between irisin levels and glucose homeostasis in obese subjects with metabolic syndrome (MetS) following an energy-restricted treatment. Ninety-six adults with excessive body weight and MetS features underwent a hypocaloric dietary pattern for 8 weeks, within the RESMENA randomized controlled trial (www.clinicaltrials.gov; NCT01087086). After the intervention, dietary restriction significantly reduced body weight and evidenced a dietary-induced decrease in circulating levels of irisin in parallel with improvements on glucose homeostasis markers. Interestingly, participants with higher irisin values at baseline (above the median) showed a greater reduction on glucose (P=0.022) and insulin (P=0.021) concentrations as well as on the homeostasis model assessment index (P=0.008) and triglycerides (P=0.006) after the dietary intervention, compared with those presenting low-irisin baseline values (below the median). Interestingly, a positive correlation between irisin and carbohydrate intake was found at the end of the experimental period. In conclusion, irisin appears to be involved in glucose metabolism regulation after a dietary-induced weight loss.

Ghrelin as a GH-releasing factor.

Growth hormone (GH) is secreted by the pituitary gland in a pulsatile manner. It is accepted that this pulsatility is primarily controlled by the hypothalamus, although this secretion can also be modulated by factors from GH-targeted organs, the pituitary and other regions of the central nervous systems, or by factors arriving from peripheral organs. In mammals, hypothalamic control of GH pulsatility is classically regulated by the interplay of two opposing hormones, stimulatory GHRH and inhibitory somatostatin (SS). Recognition of the gastric ghrelin peptide as the natural ligand for GH secretagogue receptor type 1a (GHS-R1a) added a new element to the complex physiological regulation of GH secretion and clarified some of its aspects that were previously not fully understood. In this review, we examine data that suggest that ghrelin may regulate GH secretion, as well as ghrelin's possible use as a therapeutic agent.

Oxidative stress associated to dysfunctional adipose tissue: a potential link between obesity, type 2 diabetes mellitus and breast cancer.

Diabetes mellitus and breast cancer are two important health problems. Type 2 diabetes (T2DM) and obesity are closely linked with both being associated with breast cancer. Despite abundant epidemiological data, there is no definitive evidence regarding the mechanisms responsible for this association. The proposed mechanisms by which diabetes affects breast cancer risk and prognosis are the same as the mechanisms hypothesised for the contribution of obesity to breast cancer risk. The obesity-induced inflammation promoted by adipose tissue dysfunction is a key feature, which is thought to be an important link between obesity and cancer. Inflammation induces an increase in free radicals and subsequently promotes oxidative stress, which may create a microenvironment favourable to the tumor development in obese persons. Oxidative stress is also proposed as the link between obesity and diabetes mellitus. Therefore, obesity-related oxidative stress could be a direct cause of neoplastic transformation associated with obesity and T2DM in breast cancer cells. This review is focused on the role of obesity-related oxidative stress in the context of chronic inflammation, on the time of breast cancer onset and progression, which provide targets for preventive and therapeutic strategies in the fields of diabetes and obesity-related breast cancer.

Association of breast cancer and obesity in a homogeneous population from Spain.

OBJECTIVE: To evaluate for the first time in Spain if the association between obesity and breast cancer prognosis is similar to that reported in other countries with non Mediterranean dietary patterns. METHODS: Weight and height and other variables of interest, tumor characteristics and current clinical status 3 yr after diagnosis were retrieved from medical files of breast cancer women diagnosed during 2006. A total of 159 cases with complete information were studied and categorized according to the World Health Organization criteria in normal-/under-weight, overweight, and obese. RESULTS: Among breast cancer patients, 70.4% were classified as overweight/ obese and 29.6% as normal weight. Prevalence of obesity was high (38.4%) in comparison with information reported for healthy women of the same region (27.11%) and was higher among post-menopausal patients and in women with low level of alcohol and tobacco consumption. Moreover, overweight/ obese cases (79.5%) tended to have more often human epidermal growth factor receptor 2 status negative when compared with those with normal weight (70.2%; p=0.097) and the survival curves tended to be influenced by body mass index although without statistical significance. CONCLUSIONS: Overweight/obesity in a Mediterranean country is highly prevalent among breast cancer patients. Our results support a putative influence of obesity per se and not the alimentary patterns as a prognostic factor in breast cancer patients justifying the need to perform larger prospective studies.