[pizza234]

This phenomenon (specifically, body breaking down muscles), is a very practical, and doesn't really need studies.

When doing bodybuilding (or sports in general), one can very easily measure their own bodyfat, and losing more muscle than fat is the enemy #1 during diet cycles (whose objective in fact is to minimize muscle loss and maximize fat loss).

Of course, "plenty of adipose stores" is relative. I guess that if one is 30% BF and never does any activity, as soon as they start to lift some weights, they'll put muscles and lose fat quickly for some time, independently of the calories deficit.

The other exception is when one takes anabolic steroids.