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Men and women respond differently to rapid weight loss: Metabolic outcomes of a multi-centre intervention study after a low-energy diet in 2500 overweight, individuals with pre-diabetes (PREVIEW).
Christensen, P, Meinert Larsen, T, Westerterp-Plantenga, M, Macdonald, I, Martinez, JA, Handjiev, S, Poppitt, S, Hansen, S, Ritz, C, Astrup, A, et al
Diabetes, obesity & metabolism. 2018;20(12):2840-2851
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Overweight and obesity are major risk factors for developing type 2 diabetes mellitus. Men and women respond differently to weight loss programmes, with men typically losing more weight and more abdominal fat, whilst women lose more subcutaneous fat. The aim of this large multinational study was to compare the effects of weight loss induced by an 8‐week low energy diet on metabolic outcomes in overweight men and women with prediabetes. Study participants followed the Cambridge Weight Plan which is based on four formula meals, with a total of approximately 810kcal, per day, for eight weeks. Small amounts of non-starchy vegetables were allowed, as were psyllium husks in case of digestive problems. Men lost significantly more weight than women, 11.8% versus 10.3%. Insulin resistance improved similarly in men and women, but metabolic syndrome score improved more in men than in women. Men lost more fat than women and generally had more beneficial metabolic changes. Women had higher reductions in fat-free mass, bone mineral content and HDL cholesterol than men, raising the question whether rapid weight loss may have negative longer term effects for women.
Abstract
AIMS: The PREVIEW lifestyle intervention study (ClinicalTrials.gov Identifier: NCT01777893) is, to date, the largest, multinational study concerning prevention of type-2 diabetes. We hypothesized that the initial, fixed low-energy diet (LED) would induce different metabolic outcomes in men vs women. MATERIALS AND METHODS All participants followed a LED (3.4 MJ/810 kcal/daily) for 8 weeks (Cambridge Weight Plan). Participants were recruited from 8 sites in Europe, Australia and New Zealand. Those eligible for inclusion were overweight (BMI ≥ 25 kg/m2 ) individuals with pre-diabetes according to ADA-criteria. Outcomes of interest included changes in insulin resistance, fat mass (FM), fat-free mass (FFM) and metabolic syndrome Z-score. RESULTS In total, 2224 individuals (1504 women, 720 men) attended the baseline visit and 2020 (90.8%) completed the follow-up visit. Following the LED, weight loss was 16% greater in men than in women (11.8% vs 10.3%, respectively) but improvements in insulin resistance were similar. HOMA-IR decreased by 1.50 ± 0.15 in men and by 1.35 ± 0.15 in women (ns). After adjusting for differences in weight loss, men had larger reductions in metabolic syndrome Z-score, C-peptide, FM and heart rate, while women had larger reductions in HDL cholesterol, FFM, hip circumference and pulse pressure. Following the LED, 35% of participants of both genders had reverted to normo-glycaemia. CONCLUSIONS An 8-week LED induced different effects in women than in men. These findings are clinically important and suggest gender-specific changes after weight loss. It is important to investigate whether the greater decreases in FFM, hip circumference and HDL cholesterol in women after rapid weight loss compromise weight loss maintenance and future cardiovascular health.
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A whole-grain diet reduces peripheral insulin resistance and improves glucose kinetics in obese adults: A randomized-controlled trial.
Malin, SK, Kullman, EL, Scelsi, AR, Haus, JM, Filion, J, Pagadala, MR, Godin, JP, Kochhar, S, Ross, AB, Kirwan, JP
Metabolism: clinical and experimental. 2018;82:111-117
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Literature shows that dietary whole-grain intake is associated with a lower incidence of type 2 diabetes. The aim of the study was to investigate the association between a whole-grain diet and insulin resistance and glucose use in individuals at risk for type 2 diabetes. The study was a randomized, double-blind, controlled crossover trial involving fourteen middle-aged, obese adults at risk for diabetes. Randomisation was carried out prior to metabolic testing. Results indicate that whole-grain intake as part of a mixed-meal diet significantly improved post-prandial (after a meal) glucose metabolism in middle-aged obese adults. Furthermore, both whole-grain and refined-grain interventions induced about 3–6% weight and fat loss. Authors conclude that whole-grain intake effectively promotes glycaemic control by improving insulin action.
Abstract
BACKGROUND Whole-grain intake is associated with lower risk of type 2 diabetes but the mechanisms are unclear. PURPOSE We tested the hypothesis that a WG diet reduces insulin resistance and improves glucose use in individuals at risk for type 2 diabetes compared with an isocaloric-matched refined-grain diet. METHODS A double-blind, randomized, controlled, crossover trial of 14 moderately obese adults (Age, 38 ± 2 y; BMI, 34.0 ± 1.1 kg/m2). Insulin resistance and glucose metabolism was assessed using an oral glucose tolerance test combined with isotopic tracers of [6,6-2H2]-glucose and [U-13C]-glucose, and indirect calorimetry. Peripheral and hepatic insulin resistance was assessed as 1/(rate of disposal/insulin), and endogenous glucose rates of appearance (Ra) iAUC60-240 × insulin iAUC60-240, respectively. Both diets met ADA nutritional guidelines and contained either whole-grain (50 g per 1000 kcal) or equivalent refined-grain. All food was provided for 8 wk. with an 8-10 wk. washout period between diets. RESULTS Post-prandial glucose tolerance, peripheral insulin sensitivity, and metabolic flexibility (insulin-stimulated - fasting carbohydrate oxidation) improvements were greater after whole-grain compared to the refined-grain diet (P < 0.05). Compared to baseline, body fat (~2 kg) and hepatic Ra insulin resistance was reduced by both diets, while fasting glucose and exogenous glucose-meal were unchanged after both interventions. Changes in peripheral insulin resistance and metabolic flexibility correlated with improved glucose tolerance (P < 0.05). CONCLUSION Whole-grains reduced diabetes risk and the mechanisms appear to work through reduced post-prandial blood glucose and peripheral insulin resistance that were statistically linked to enhanced metabolic flexibility.
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Effect of Vitamin D Supplementation on Obesity-Induced Insulin Resistance: A Double-Blind, Randomized, Placebo-Controlled Trial.
Cefalo, CMA, Conte, C, Sorice, GP, Moffa, S, Sun, VA, Cinti, F, Salomone, E, Muscogiuri, G, Brocchi, AAG, Pontecorvi, A, et al
Obesity (Silver Spring, Md.). 2018;26(4):651-657
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Vitamin D concentration has been inversely associated with impaired glucose regulation, insulin resistance and risk of metabolic dysfunction. The aim of the study was to evaluate whether Vitamin D supplementation could improve insulin sensitivity in patients with a high risk of diabetes. The study is a randomised, double-blind, placebo-controlled trial. The participants with obesity were supplemented with Vitamin D or placebo on top of a hypocaloric diet. Results indicate that Vitamin D supplementation combined with weight loss is linked with a significant improvement in insulin sensitivity in vitamin D deficient participants with obesity.
Abstract
OBJECTIVE The aim was to investigate whether vitamin D supplementation, combined with a hypocaloric diet, could have an independent effect on insulin sensitivity in subjects with both overweight and hypovitaminosis D. Changes from baseline in anthropometric parameters, body composition, glucose tolerance, and insulin secretion were considered as secondary outcomes. METHODS Eighteen volunteers who were nondiabetic and vitamin D deficient and had BMI > 25 kg/m2 were randomized (1:1) in a double-blind manner to a hypocaloric diet + either oral cholecalciferol at 25,000 IU/wk or placebo for 3 months. Hyperinsulinemic-euglycemic clamp to measure insulin sensitivity was performed at baseline and after intervention. RESULTS Body weight in both groups decreased significantly (-7.5% in the vitamin D group and -10% in the placebo group; P < 0.05 for both), with no between-group differences. Serum 25-hydroxyvitamin D levels in the vitamin D group increased considerably (from 36.7 ± 13.2 nmol/L to 74.8 ± 18.7 nmol/L; P < 0.001). Insulin sensitivity in the vitamin D group improved (from 4.6 ± 2.0 to 6.9 ± 3.3 mg·kg-1 ·min-1 ; P < 0.001), whereas no changes were observed in the placebo group (from 4.9 ± 1.1 to 5.1 ± 0.3 mg·kg-1 ·min-1 ; P = 0.84). CONCLUSIONS Cholecalciferol supplementation, combined with a weight loss program, significantly improves insulin sensitivity in healthy subjects with obesity and might represent a personalized approach for insulin-resistant subjects with obesity.