Long-Term Supplementation with Leucine Does Not Prevent Development of Obesity in Rats Fed a High-Fat Diet

Excess dietary fat consumption has been implicated in the development of obesity and diabetes. Obesity can be characterized by a disproportionate increase in fat mass compared to lean body mass. However, if muscle mass can be increased or maintained in obesity, this may facilitate weight loss by increasing the body’s overall metabolic capacity. Historically, supplementation with the branched-chain amino acid leucine has been shown to increase muscle protein synthesis via the protein kinase mTORC1. Recent studies suggest that supplementation with leucine also has the potential to reduce weight gain and fat deposition in high-fat fed, obese mice. The objective of this study was to determine if long-term dietary leucine supplementation prevents development of obesity in rats meal-fed a high fat (60%) diet. Male, Sprague-Dawley rats (n=30/dietary treatment) were meal-fed (3 meals/day) either a control diet (C), control+leucine (CL), high-fat (HF), or high-fat+leucine (HFL) for 42 days. HF/HFL-fed rats gained, 28 g more than rats fed C/CL diets (