Effects of Energy and Macronutrient Cycling on Weight Loss, Body Composition, and Markers of Health in Obese Women Participating in a Resistance-Based Exercise Program

Purpose: To determine whether adherence to a repeating 30-d non-linear diet intervention while participating in a supervised exercise program that includes resistance-exercise would promote weight and fat loss without weight loss plateau and whether alterations in carbohydrate and protein intake may influence results. Methods: Fifty sedentary and obese pre-menopausal females (35.2±7.6 years; 88.7±18 kg, 32.6±6 kg/m2, 42.5±4.2% fat) were randomly assigned to an exercise-only (EX) or EX plus diets containing higher proportions of carbohydrate or protein. Diets were hypoenergetic for 30-d (7-d at 1,200 kcals/d, 21-d at 1,500 kcal/d), more isoenergetic for 30-d (2,200 kcals/d), and repeated three times during a 24-wk intervention. Diets were either 45:30:24 (HCD) or 30:45:25 (HPD) carbohydate:protein:fat. All participants performed 30-min resistance exercise (3 d/wk) and a brisk walking program (3 d/wk). Data were analyzed by general linear model (GLM) statistics with repeated measures and presented as mean changes from baseline (mean [UL, LL]). Results: Participants experienced a significant and reduction in body weight (EX -2.24 [-6.5, 2.0], EX+HCD -6.99 [-9.4, -4.5], EX+HPD -4.49 [-7.1, -1.8] %), fat mass (EX -3.45 [-10.9, 4.03], EX+HCD -12.15 [-16.4, -7.9], EX+HPD -8.54 [-13.2, -3.9] %), and percent body fat (EX -1.30 [-5.6, 3.0], EX+HCD -5.91 [-8.3, -3.5], EX+HPD -4.31 [-7.0, -1.6] %) with those in the EX+HCD experiencing a more linear response. Participants in the EX and EX+HCD groups maintained fat-free mass to a better degree (EX -0.89 [-4.0, 2.2], EX+HCD -3.21 [-5.0, -1.2], EX+HPD -1.92 [-3.8, 0.002] %). Participants dieting generally experiencing greater benefit with some evidence that those in the EX+HPD experienced greater changes in blood lipids. Conclusion: A 30-day repeated non-linear diet can promote fat and weight loss without a plateau. Consuming a HPD may help maintain fat-free mass during weight loss and improve some markers of health compared to HCD interventions.