The source of protein, whether whey or soy, has been largely debated for decades in the world of fitness and health. Advocates of soy protein claim that the source of protein does not matter and that the effects of soy protein is equivalent to that of whey protein, if not better. However, opponents of soy protein have based their arguments upon the decreased bioavailability of soy protein and suggest that whey protein is significantly better for all health goals.
Another argument is based upon the claim that soy protein increases estrogen in men, which is detrimental to both weight loss and building muscle mass. In a recently published study done by the Journal of Nutrition with regards to whey versus soy protein, it has become evident that whey protein is, in fact, superior to soy protein – at least in regards to weight loss.
Retaining Muscle while Losing Weight
When attempting to lose weight, the most important factor to consider is to retain as much muscle mass while decreasing the amount of fat in the body. In order to do so, one should eat less in order to enter a hypocaloric state so that the body turns to other sources of energy, so that the body will burn fat instead of the food consumed. However, in a caloric deficit, myofibrillar protein synthesis decreases and the body ends up utilizing muscle mass as a source of energy along with the fat, which is unfavorable.
The problem of muscular atrophy during weight loss is a problem that many encounter, and in order to preserve as much lean muscle mass, resistance training is suggested as a means to minimize the loss of the lean mass. Along with resistance training, one should also be consuming enough protein in order promote myofibrillar protein synthesis so that muscle loss is kept to a minimum.
The Study: Whey Protein Supplementation Preserves Postprandial Myofibrillar Protein Synthesis during Short Term Energy Restriction
The aim of the study was to determine whether the source of protein (whey vs. soy) affected the rate of myofibrillar protein synthesis (higher rates lead to retaining more muscle mass) and lipolysis (fat loss). Participants of the study were separated into three groups: one group consumed whey protein, another group consumed soy protein, and the last group consumed carbohydrates. All other variables were held constant, such as activity level and total calories consumed. Baseline characteristics were taken at the beginning of the study and at the conclusion of the study.
The Results of the Study
At the end of the study, all three groups achieved similar rates of lipolysis and weight loss; however, the group that consumed whey protein had significantly higher rates of myofibrillar protein synthesis, meaning that whey protein is more efficacious in both building muscle and retaining muscle during weight loss.
In conclusion, results from the study suggest that whey protein is superior to soy protein. Whey protein promotes higher rates of myofibrillar protein synthesis, which helps us to build muscle mass and retain muscle mass during weight loss, so if you decide to embark on a diet, make sure to consume whey protein twice a day to minimize the amount of muscle loss!