Cut Calories Moderately
The surest way to lose lean body mass along with fat is to cut your daily calorie intake drastically. In a study performed at Rockefeller University, one group of subjects cut their energy intake by 700 calories a day, while a second group cut their energy intake by 300 calories a day. The first group lost more total weight, but it was only 48 percent fat—the rest was lean body mass. Meanwhile, the weight lost by the second group was 91 percent fat.
When trying to lose excess body fat, limit your daily energy deficit to roughly 300 calories per day. This is especially important during periods of intensive training, when you need plenty of energy to fuel workouts and recovery.