Whey protein enhances fat loss
by Jeff S. Volek, Ph.D., R.D.
Whey protein has been proposed to be an ideal source of protein during weight loss due to its nutrient partitioning effects that would enhance fat loss and preserve lean tissue. A distinguishing feature of whey is that it is a complex protein source with a high prevalence of essential amino acids, which are needed for stimulating skeletal muscle protein synthesis. Whey also contains a higher proportion of branched-chain amino acids (BCAAs), especially leucine, which triggers protein synthesis and helps build lean body mass.
In addition to promoting muscle anabolism and strength, there is evidence that whey protein may also promote weight loss and fat loss. In a preliminary study, overweight men and women assigned to a whey protein group lost significantly more weight and body fat than the carbohydrate supplement group with no other changes in habitual diet and exercise habits. Greater weight and fat loss could be attributed to an increased thermogenesis because higher quality animal proteins induce greater 24-hour thermic effects compared to soy and equal amounts of carbohydrate.
Since whey is nutrient dense but relatively low in energy (approximately 4 kcal per gram), supplementation is an efficient method to promote skeletal muscle anabolism while promoting catabolism in fat cells and therefore is hypothesized to improve both muscle growth and fat loss.
Researchers confirmed these effects in a recent 12-week trial that involved overweight subjects consuming whey protein containing 10 grams of protein 20 minutes before breakfast and another 10 grams 20 minutes before dinner. About 25% of the amino acids in the whey protein were BCAAs, half of which was leucine.
A control group consumed a beverage matched for calories. At the end of the 12 weeks, fat loss was nearly two-fold greater in the whey group (6.2 lbs. vs 3.5 lbs.) and lean body mass was better preserved in the whey group (-1.7 lbs. vs -3.4 lbs).
Thus, daily intake of a small amount of whey (10 grams) before breakfast and dinner was able to enhance fat loss while preserving lean body mass during weight loss.