Lose fat and maintain muscle with a high-protein diet that provides a large dose of amino acids at every meal. It is well known that humans lose muscle along with fat when they go on a diet that creates a negative energy balance. However, it is possible that by eating enough protein at every meal, a loss of muscle mass can be avoided, while still producing significant fat loss.
A new study in Obesity Journal showed that the reason people on energy-restricted diets lose muscle along with fat is due to an increased rate of muscle protein breakdown rather than a slower rate of muscle protein building. Researchers had overweight adults go on a weight loss diet for a year that provided 1.0 g/kg of body weight of protein a day and an energy deficit of 500 calories. Participants lost 7 percent of their body weight (about 3 kg of lean mass and 5 kg of fat) by three months. After a year, they lost 10 percent of their body weight (about 2 kg of fat mass and no more lean mass).
Protein synthesis rates did not slow at any point during the study. Plus, after eating a meal, protein synthesis was actually enhanced over baseline. This was surprising because studies of animals that are put on similar diets have shown that muscle is lost during energy restriction due to depressed rates of protein synthesis. A lack of calories in the long-term means the anabolic response to feeding is blunted. However, in humans, it appears the anabolic response to eating is maintained. Muscle loss must come from increased rates of protein breakdown, probably in between meals.
A solution is to ensure you get regular doses of protein at every meal and snack in order to continually trigger protein synthesis and avoid muscle loss. A recent review of how various protein doses affect body composition found that eating at least 2.38 g/kg/body weight or protein a day may be necessary to avoid lean tissue loss. High-quality solid protein from food rather than liquid protein appears to be the most effective for avoiding muscle loss. For example, a study found that eatingmoderately-sized high-protein meals of 4 ounces of meat during the day is more effective at elevating protein synthesis rates than eating one large high-protein meal (12 ounces of meat once a day).
In addition, if you want to limit the total amount of energy you eat, it is necessary to get the most amino acids out of the food you do eat. High-quality protein from animal sources is your best choice. Still, supplemental protein can help you achieve that large daily dose of protein, especially for snacks. Studies suggest whey protein is the superior source for building muscle.
In addition, one amino acid in particular, leucine, is necessary to achievepeak protein synthesis levels in the body. In the ObesityJournal study, a reduction in leucine in the body appeared to be proportional to the loss of lean mass.
The good news is that meat, especially beef and chicken, contain large quantities of leucine, as does whey protein. Get extra leucine by taking branched-chain amino acids (BCAAs) before and after your workouts for best body composition results. For older trainees over 40, research suggests leucine is more important than for younger folks because there is a critical pathway for muscle building that won’t be activated unless large concentrations of leucine are present.
Bosse, J., Dixon, B. Dietary Protein To Maximize Resistance Training: A Review and Examination of Protein Spread and Change Theories. Journal of the International Society of Sports Nutrition. 2012. Published Ahead of Print.
Villareal, D., Smith, G., et al. Effect of Weight Loss on the Rate of Muscle Protein Synthesis During Fasted and Fed Conditions in Obese Older Adults. Obesity Journal. 2012. 20(9), 1780-1786.