Effects of a BCAA-supplemented Hypocaloric Diet Versus a Standard Hypocaloric Diet on Weight Loss, Lean Mass Preservation and Improvement of Insulin Sensitivityand Its Benefits Over a High-protein Hypo-caloric Diet.

The prevalence of obesity globally and in Singapore continues to rise despite increased public awareness and efforts to control weight. Its association with chronic metabolic diseases, including diabetes, hypertension, cardiovascular diseases, signify the serious implications of obesity on public health. There remains, however, no scientific consensus on the optimal methods for weight loss and its maintenance over longer periods of time. The Atkins diet was introduced in the late 1990s and has since fuelled the popularity of using high-protein diets for weight loss. Scientific evidence have since shown high-protein diets to be more effective than conventional low-fat, high-carbohydrate diets in producing greater weight loss, at least in the short-term. More importantly, high-protein diets also reduce the amount of lean tissue lost during weight loss and may help to maintain weight loss to a greater extent than conventional diets. However, high-protein diets are also known to raise esterol, albeit improving TG and HDL-cholesterol levels. This could be due to the higher amounts of saturated fats that accompany foods rich in animal protein. In addition, high-protein diets may lower bone mineral density and impact on kidney function. High-protein diets are also more expensive than conventional low-fat, high carbohydrate foods , which is an important consideration for longer term compliance.

Supplements containing branched-chain amino acids (BCAA:leucine, isoleucine and valine) are commonly used among muscle builders and athletic community. BCAAs have been shown to stimulate protein synthesis and preserve lean mass. While a few studies have examined BCAA supplementation with low protein diets for weight loss and found depletion of other essential amino acids, the effects of BCAA supplementation with moderate-protein hypocaloric diets on lean mass preservation during weight loss in energy-restricted obese patients has, to our knowledge, not been investigated. Compared to consuming a high (animal) protein diet, which is also rich in BCAAs, taking BCAA supplements would be a much more convenient and affordable way to obtain similar if not greater quantities of BCAA, without the adverse health effects of a high-protein load on the body.

In this study investigators primarily aim to investigate in overweight/obese subjects, whether a BCAA-supplemented (moderate-protein) hypocaloric diet (BCAA) when compared to a standard (moderate-protein) hypocaloric diet (CT) will result in greater lean mass preservation, resting and diet-induced energy expenditure, and improved insulin sensitivity. Investigators will also examine the effects on lean mass preservation and insulin sensitivity changes between BCAA-supplemented diet and high-protein hypocaloric diet (HP). As a secondary aim, investigators have also powered the study to examine if the BCAA-supplemented diet has added advantage to the high-protein diet by incurring less negative effects on bone mineral density and renal function.

In addition, investigators will determine the participant's compliance to the diet versus supplements as a weight loss and maintenance strategy. The findings of this study will provide us novel insight on BCAA-supplementation in the hypocaloric diet. If this study is successful, BCAA-supplementation on a hypocaloric diet could provide an alternative to a standard (moderate-protein) hypocaloric diet for weight reduction strategy without the attending potential health risks of a high protein load e.g. reduced bone mineral density and detrimental effects on renal function.

There are three main hypotheses which investigators propose to examine.