Comparison of Different Weight Loss Diets With Different Protein Content

High-protein diets better preserve lean mass than conventional low-fat diets. However, they are costly and have potential health risks. Preserving lean mass is important for sustaining high resting energy expenditure, leading to greater initial weight loss, better weight maintenance and improving blood sugar levels. Branched-chain amino acids (BCAA) supplements are known to preserve lean mass but their effects during weight loss have not been examined. Investigators want to investigate if a BCAA-supplemented diet is more effective than a standard hypocaloric diet in terms of the aforementioned benefits, and yet has less detrimental effects than a high-protein diet for weight loss. Using a 16-week weight loss and 8-week weight maintenance intervention, overweight and obese men and women will be randomized to either a hypocaloric diet with BCAA or placebo supplements or a high-protein diet with placebo supplements. Participants' compliance to the diet versus supplements will be compared. Body composition, resting and diet-induced energy expenditure, insulin sensitivity will be measured and blood samples taken before and after weight loss. These findings will inform on the benefits of BCAA-supplementation during energy restriction and may offer an alternative cost-effective strategy for weight loss and maintenance, without the adverse health effects of a high-protein load.