If you look at studies of alternate daily fasting, for example, they've done studies where they've compared calorie restriction with alternate daily fasting over a period of 32 weeks. They measured lean mass at the end of it. In fact, the calorie restriction people, their lean mass percentage went up by 0.5% because they had lost some weight, but the alternate daily fasting group went up by 2.2% So, in other words, the fasting group was four times better at preserving lean mass.
