Saving Muscle While You Reduce Calories

Several studies have been published from the CALERIE study data with even more interesting revelations, so I’ll review several over the next few Memos. I’ll start with changes in body composition in those who restricted calories (143 subjects) and those who continued to eat normally (75 subjects), often called ad lib or ad libitum. Remember, the purpose of the study was to achieve a 25% reduction in calorie intake and sustain it for two years in subjects who began at normal BMI.

The caloric restriction (CR) group achieved only an 11.9% decrease in CR over two years but still showed significant changes:

• 16.7 pounds decrease in weight compared with a one pound gain in the ad libitum (AL) group
• A decrease in waist circumference of 2.4 inches versus a 0.5 inch increase
• Fat mass decrease of 11.9 pounds compared with a 1.1 pound gain
• A 4.4 lb. decrease in fat-free mass compared with no change at 24 months
• Although the CR subjects lost some fat-free mass, the loss of fat exceeded the expected proportional loss found in the typical weight loss program of 50% fat mass and 50% fat-free mass

That’s the surprising result: the study showed that a moderate reduction in calories did not abnormally impact the proportion of muscle loss to fat loss: fat loss exceeded muscle loss. Rather than protein intake, the calories used in activity contributed to sustaining muscle mass—exercise helped maintain muscle.

We’ll examine another paper from the CALERIE Study on Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: Am J Clin Nutr 2017;105:913–27.