Diet for the Maintenance of Weight Loss and Metabolic Health in Obese Postmenopausal Women

Overview

The aim of the study will be comparing the effectiveness of two diets: moderate in fat with a high proportion of monounsaturated fatty acids (MUFAs) - the Mediterranean diet (MED) and 2) the low in fat and high in dietary fiber contents the dietary approaches to stop hypertension diet (DASH) on weight maintenance and cardiovascular risks following a recent body weight reduction in centrally obese postmenopausal women. The tested diets will be given ad libitum manner. Moreover, adherence to both prescribed weight-loss maintenance diets will be also evaluated by the plasma concentration of alkylresorcinols (AR) as a possible whole grain wheat/rye dietary biomarker and by the analysis of fatty acids profile in erythrocyte membranes as a dietary biomarker of a fatty acids consumption. The participants of this study will be 150 non-smoking, postmenopausal women with central obesity, who wished to lose weight and have at least one other criterion of metabolic syndrome. The intervention will include 3 phases: Phase I (weeks 1-8), weight loss dietary intervention with 700 kcal/d energy deficit, Phase II (week 9-32), weight loss maintenance intervention for those participants losing ≥10% initial body weight the MED or the DASH diet will be offered in a random manner. The control group will receive oral dietary recommendations based on the Harvard model "Healthy Eating Plate". After this 32 weeks period will be finished, the participants will be discharged to the community with no contact by study personnel, until the 52-weeks follow-up period (Phase III).

The treatment of obesity can present a challenge because of the difficulty in maintaining body weight loss beyond one year. The aim of the study will be comparing the effectiveness of two energy-unrestricted diets containing different amount of macronutrients: 1) moderate in fat with high amounts of MUFAs - the MED diet and 2) low in fat with high dietary fiber contents - the DASH diet, on maintenance of weight loss and metabolic outcomes following a recent weight loss in centrally obese postmenopausal women. Since the outcomes of dietary interventions may depend greatly on adherence to the diet, we will measure the plasma AR concentrations and fatty acids profile in red blood cells (RBC). Plasma AR concentrations is a valid marker of intake of whole-grain wheat/rye in the DASH diet and fatty acids concentration in RBC is a valid marker of fatty acids intake (especially MUFAs) in the MED diet. A total of 150 non-smoking, centrally obese, with at least one other criterion of metabolic syndrome postmenopausal women up to 65 old years will be qualified. This study will be divided into 3 phases: * Phase I lasting eight weeks (weeks 1-8). All participants will be introduced to a weight loss intervention with a daily energy deficit of 700 kcal per day. During this phase, changes in body weight and body composition (DEXA) and waist circumference will be measured every four weeks. Moreover, at each control visit, compliance with the prescribed diets will be measured by three-day food records. Moreover, the physical activity level will be done. Before and after weight loss phase changes in lipid and non-lipid parameters as well as eating behavior will be measured. * Participants who will loss ≥10% initial body weight will be randomly assigned to phase II of the study (weight loss maintenance intervention). This phase will be lasting 24 weeks (weeks 9-32). Participants will receive the MED (n = 50) or DASH diet (n = 50). The control group (n = 50) will receive oral dietary recommendations based on the Harvard model "Healthy Eating Plate". During this phase, changes in body weight, body composition, and waist circumference will be measured every four weeks. Moreover, at each control visit, compliance with the prescribed diets will be measured by three-day food records. Moreover, the physical activity level will be done. Before and after weight loss phase changes in lipid and non-lipid parameters as well as valid markers of whole-grain wheat/rye and faty acids intake and eating behavior will be measured. * After this 32 weeks period will be finished, the participants will be discharged to the community with no contact from study personnel for 20 weeks, until follow-up at 52 weeks study (Phase III - weeks 33 - 52). After this time changes in body weight, body composition and waist circumference will be measured. Moreover, the physical activity level will be done again and changes in lipid and non-lipid parameters, as well as valid markers of intake and eating behavior, will be measured.