In a sense, yes - to build up your muscles they must first be broken down, a cycle which is going to create some amount of stressful churn. If you think about a

In a sense, yes - to build up your muscles they must first be broken down, a cycle which is going to create some amount of stressful churn. If you think about any machine, a higher operating energy/intensity generally correlates to faster breakdown. At the same time, humans in good shape are definitely healthier, and too much calorie restriction can lead to malnourishment. There's a sweet spot somewhere, proponents of calorie restriction are basically saying to err on the side of eating less.