Anyone who's ever dieted knows that a primary problem associated with calorie reduction is the possible loss of muscle. That's especially true if you follow a diet plan that's low in calories in relation to your activity level. Unless you make sure you're getting enough protein, your weight loss may consist of as much as 50 percent lean mass, or muscle. Not even anabolic steroids will preserve muscle under ultra-low-calorie conditions for extended periods. That's the reason for the frequent recommendation that you shouldn't try to lose more than two pounds a week.
With the reduction in calories required to change body composition'that is, lose fat'energy levels also decline. That leads to a reduction in training intensity, which also contributes to muscle loss. Creatine increases the efficiency of muscle energy stores by acting as a backup for the regeneration of ATP in cells by donating a phosphate molecule. Considering that function of creatine, it makes sense that it may help you maintain muscle phosphagen stores while dieting.
A new study examined the role of creatine in maintaining muscle energy stores during calorie restriction.1 It involved 16 males, ages 18 to 26, who'd been training with weights for at least two years, three to six times a week, and who had no reported history of anabolic steroid use. The men were divided into two groups, with one group taking 20 grams of creatine daily for four days and the other taking a placebo, or inactive substance. Both groups ate the same diet, which consisted of 54.7 percent carbohydrate, 21.3 percent protein and 24 percent fat. The researchers tested creatine's effect on anaerobic exercise performance by having the men do 10 sprints of six seconds each, with a 30-second rest after each sprint.
Both groups averaged a 3.7 percent weight loss on the diet. The muscle levels of creatine didn't change in either group, likely the result of the short-term nature (four days) of the study. The percentage of change for fat-free mass was slightly lower for the placebo group, although measurement of nitrogen loss was similar for the two groups, indicating that both groups lost about the same amount of protein. Although the men took in .96 grams of protein per kilogram of bodyweight, which exceeds the .8 grams often suggested as sufficient, the fact that they still excreted nitrogen shows that it wasn't enough protein.
The group that got the creatine increased muscle creatine stores by 16 percent, or about the same as seen with a typical creatine-load cycle (20 grams daily for five to six days). That indicates you can still benefit from creatine loading even while dieting. The creatine also benefited exercise performance, with the creatine group showing a 4.6 percent increase in performance after the fourth sprint test. In contrast, those in the placebo group showed a 1.1 percent drop in work performance.
The creatine group also lost less fat-free mass than the placebo group. Since the percentage of nitrogen loss was similar for both groups, the difference shown by the creatine group was probably due to water retention. Another study showed that after the subjects took creatine for three days, total body water increased by 2 percent, while intracellular water increased by 3 percent. The intracellular water retention promotes cellular hydration, which in turn acts as an anabolic cellular signal.
The new study concluded that it may be advantageous to take creatine when you're on a calorie-restricted diet because it maintains muscle energy stores and consequent muscle training efficiency.
1 Rockwell, J.A., et al. (2001). Creatine supplementation affects muscle creatine during energy restriction. Medicine and Science in Sports and Exercise. 33:61-68.