Cut fewer calories
Obviously, if just cutting calories is going to result in so much muscle loss, you want to back away from any low-calorie diet. “In general a female should reduce calories by about 300 to 400 calories and males about 400 to 600 calories,” says Bill Campbell, director of the Performance and Physique Enhancement Laboratory at the University of South Florida. “A better way to approach this is to determine what one’s maintenance calories are, and then reduce this amount by approximately 25 percent.”
Maintenance calories are the number of calories you need to eat per day to maintain your weight at any given time, factoring in things like exercise, which we’ll get to later. While the most accurate way to determine how many calories you burn per day is to spend 24 hours in a laboratory’s metabolic chamber—a room that measures the ratio of carbon dioxide in the room— the Mayo Clinic has an online tool for roughly estimating your maintenance calories. (Choose “I Want to Maintain My Current Weight.”) Multiply that number by 0.75, and that’s a pretty good target for losing weight slowly, he says.
That’s right: A small caloric deficit will help you lose weight slowly, which will help reduce the amount of fat-free mass that you lose, Campbell says. For example, in one study, athletes either lost 1.4 percent of their body weight per week (for a 200-pound person, that would equal 2.8 pounds per week) or 0.7 percent of their body weight per week (for the same 200-pound person, that would equal 1.4 pounds per week). Both groups lost the same amount of total weight, but while the fast weight-loss group lost 7 pounds of fat and 0.66 pounds of lean mass, the slow weight-loss group lost 11 pounds of fat and gained 2 pounds of lean mass.