Need to lose weight for a performance, competition, or vacation? Reducing calories is the obvious choice, but losing muscle in the process is something we all hope to avoid.
A caloric reduction should be accompanied by an increase in protein consumption to avoid catabolism (muscle loss).
Research on hypocaloric (low calorie) diets with elevated protein intake is typically conducted with overweight or obese samples. How does this strategy impact athletes or active individuals?
To evaluate the role of protein when dieting, Mettler et al. (2010) examined the effect of typical-protein and high-protein consumption on lean mass retention among men who followed hypocaloric diets. Participants were 20 men who had engaged in resistance training for at least 6 months. The study lasted 4 weeks. In the first week, energy intake and output were measured. In the second week, participants were provided with maintenance calorie diets.
Participants were matched by physical characteristics then randomly assigned to one of two groups. The control group consumed 15% of daily calories from protein; the high-protein group consumed 35% of daily calories from protein. For the third and fourth weeks of the study, both groups consumed hypocaloric diets with 60% of typical energy intake. Meals were prepared to prevent knowledge of group membership—19 of 20 participants believed they were the in high-protein condition.
After two weeks, changes in weight, body composition, athletic performance, and various health outcomes were assessed. I’ll focus only on weight and body composition here. In the table below, you can see the differences between the groups. The control group lost more weight overall (control group: 3.0 kg or 6.6 lb; high-protein group: 1.5 kg or 3.3 lb). However, the control group also lost more lean mass (control group: 1.6 kg or 3.5 lb; high-protein group: 0.3 kg or .66 lb). There was no difference between the groups in fat loss.
The data are clear. In only two weeks, a caloric reduction without elevating protein intake resulted in a loss of 3.5 pounds of lean mass. Those who increased protein intake while following a hypocaloric diet lost less than a pound of lean mass. Dancers, weight-class athletes, and fitness-conscious individuals can benefit from increases in protein consumption when following a weight reducing diet.
Source: Mettler, S., Mitchell, N., & Tipton, K. D. (2010). Increased protein intake reduces lean body mass loss during weight loss in athletes. Medicine and Science in Sports and Exercise, 42, 326-337.