Objective. Weight regain is associated with the promotion of insulin resistance. The newly discovered myokine irisin, which was proposed to be involved in the management of insulin sensitivity, could play a role in this process. This study aimed to investigate the association between irisin and reduced insulin sensitivity induced by weight regain.Materials/Methods. Insulin sensitivity was evaluated according to the homeostasis model assessment of insulin resistance (HOMA-IR) in 136 obese patients who followed an eight-week hypocaloric diet (30% reduced energy expenditure) to lose weight and were reevaluated four or six months after treatment. Irisin plasma levels, as well as the levels of leptin, adiponectin, ghrelin and TNF-α, were quantified in a sub-cohort (n=73) from the initially studied patients at baseline (T0), at the diet endpoint (T1) and after the follow-up period (T2).Results. After a successful dietary intervention to lose weight, 50% of the patients who regained the lost weight during the follow-up period were categorized as insulin resistant (HOMA-IR≥2.5) compared with only 25% of patients who maintained the weight loss (p=0.018). Importantly, in addition to the well-studied hormones leptin and adiponectin, irisin plasma levels were statistically associated with several risk factors for insulin resistance.Indeed, the increased risk of insulin resistance during the follow-up period was related to high irisin levels at baseline (odds ratio=4.2; p=0.039).Conclusions. Circulating irisin predicts the insulin resistance onset in association with weight regain. Therefore, irisin could be secreted as an adaptive response to counteract the deleterious effect of excess adiposity on glucose homeostasis.

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.

BackgroundDietary strategies seem to be the most prescribed therapy in order to counteract obesity regarding not only calorie restriction, but also bioactive ingredients and the composition of the consumed foods. Dietary total antioxidant capacity (TAC) is gaining importance in order to assess the quality of the diet.MethodsNinety-six obese adults presenting metabolic syndrome (MetS) symptoms completed an 8-week intervention trial to evaluate the effects of a novel dietary program with changes in the nutrient distribution and meal frequency and to compare it with a dietary pattern based on the American Heart Association (AHA) guidelines.Anthropometric and biochemical parameters were assessed at baseline and at the endpoint of the study, in addition to 48-hours food dietary records.ResultsBoth diets equally (p > 0.05) improved MetS manifestations. Dietary TAC was the component which showed the major influence on body weight (p = 0.034), body mass index (p = 0.026), waist circumference (p = 0.083) and fat mass (p = 0.015) reductions. Transaminases (ALT and AST) levels (p = 0.062 and p = 0.004, respectively) were associated with lower TAC values.ConclusionRESMENA diet was as effective as AHA pattern for reducing MetS features. Dietary TAC was the most contributing factor involved in body weight and obesity related markers reduction.Trial registrationhttp://www.clinicaltrials.gov; NCT01087086

The long-term effects of dietary strategies designed to combat the metabolic syndrome (MetS) remain unknown. The present study evaluated the effectiveness of a new dietary strategy based on macronutrient distribution, antioxidant capacity and meal frequency (MEtabolic Syndrome REduction in NAvarra (RESMENA) diet) for the treatment of the MetS when compared with the American Heart Association guidelines, used as Control. Subjects with the MetS (fifty-two men and forty-one women, age 49 (SE 1) years, BMI 36·11 (SE 0·5) kg/m 2 ) were randomly assigned to one of two dietary groups. After a 2-month nutritional-learning intervention period, during which a nutritional assessment was made for the participants every 15 d, a 4-month self-control period began. No significant differences were found between the groups concerning anthropometry, but only the RESMENA group exhibited a significant decrease in body weight (2 1·7 %; P¼ 0·018), BMI (21·7 %; P¼ 0·019), waist circumference (21·8 %; P¼ 0·021), waist:hip ratio (2 1·4 %; P¼0·035) and android fat mass (2 6·9 %; P¼ 0·008). The RESMENA group exhibited a significant decrease in alanine aminotransferase and aspartate aminotransferase (AST) concentrations (226·8 %; P¼0·008 and 2 14·0 %; P¼0·018, respectively), while the Control group exhibited a significant increase in glucose (7·9 %; P¼ 0·011), AST (11·3 %; P¼ 0·045) and uric acid (9·0 %; P,0·001) concentrations. LDL-cholesterol (LDL-C) concentrations were increased (Control group: 34·4 %; P, 0·001 and RESMENA group: 33·8 %; P, 0·001), but interestingly so were the LDL-C:apoB ratio (Control group: 28·7 %; P,0·001, RESMENA group: 17·1 %; P¼0·009) and HDL-cholesterol concentrations (Control group: 21·1 %; P, 0·001, RESMENA group: 8·7; P¼ 0·001). Fibre was the dietary component that most contributed to the improvement of anthropometry, while body-weight loss explained changes in some biochemical markers. In conclusion, the RESMENA diet is a good long-term dietary treatment for the MetS.

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Scope: Adherence to the Mediterranean diet has been associated with a reduced risk of metabolic syndrome (MetS). Metabolomics approach may contribute to identify beneficial associations of metabolic changes affected by Mediterranean diet-based interventions with inflammatory and oxidative-stress markers related to the etiology and development of the MetS. Methods and results:Liquid chromatography coupled to quadrupole-time of flight-MS metabolic profiling was applied to plasma from a 6-month randomized intervention with two sequential periods, a 2-month nutritional-learning intervention period, and a 4-month self-control period, with two energy-restricted diets; the RESMENA diet (based on the Mediterranean dietary pattern) and the Control diet (based on the American Heart Association guidelines), in 72 subjects with a high BMI and at least two features of MetS. The major contributing biomarkers of each sequential period were lipids, mainly phospholipids and lysophospholipids. Dependency network analysis showed a different pattern of associations between metabolic changes and clinical variables after 2 and 6 month of intervention, with a highly interconnected network during the nutritional-learning intervention period of the study. Conclusion: The 2-month RESMENA diet produced significant changes in the plasma metabolic profile of subjects with MetS features. However, at the end of the 6-month study, most of the associations between metabolic and clinical variables disappeared; suggesting that adherence to healthy dietary habits had declined during the self-control period.

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