Food for Thought
Forty young men underwent a month of hard exercise while cutting the dietary energy they would normally require by about 40%. “It was a grueling affair,” said Stuart Phillips, PhD, a professor in the department of kinesiology at McMaster and senior investigator on the study, which was published in the January 27 edition of the American Journal of Clinical Nutrition (2016. doi:10.3945/ajcn.115.119339). “These guys were in rough shape, but that was part of the plan. We wanted to see how quickly we could get them into shape: lose some fat, but still retain their muscle and improve their strength and fitness.”
The researchers divided their subjects into two groups. Both groups went on a low-calorie diet, one with higher levels of protein than the other. The higher-protein group experienced muscle gains—about 2.5 pounds—despite consuming insufficient energy, whereas the lower-protein group did not add muscle.
The lower-protein group at least had the consolation of not losing muscle, which is a predictable outcome of cutting calories and not working out, according to the investigators.
“Exercise, particularly lifting weights, provides a signal for muscle to be retained even when you’re in a big calorie deficit,” Phillips explained. Researchers were intrigued because the high-protein group also lost more body fat.
“We expected the muscle retention,” said Phillips, “but were a little surprised by the amount of additional fat loss in the higher protein consuming group.”
Results showed that the high-protein group lost about 10.5 pounds and the low-protein group shed only 8 pounds. All of the participants, by virtue of the demanding 6-days-a-week exercise routines, got stronger and fitter and were generally in better shape by the end of the study.
However, researchers cautioned that this regimen is not for everyone: “We designed this program for overweight young men, although I’m sure it would work for young women too, to get fitter, stronger and to lose weight fast. It’s a tough program and not something that’s sustainable or for those looking for a quick and easy fix,” Phillips said. “We controlled their diets, we supervised the exercise, and we really kept these guys under our ‘scientific’ thumb for the 4 weeks [they] were in the study.”
Phillips and his team hope to conduct a follow-up study on women and also explore a different approach that he describes as “a little easier and much more sustainable.”