My interpretation is nothing more than a logical summation of various facts, each of which has relevant support studies that I'm too lazy to quote right now: Body tends to use more of the ingested food when being fed rather than stored supplies (liver glycogen, fat, lean tissue) When food supply is (intentionally or not) low body notices the low concentration of blood glucose and tends to switch to using more of the stored supplies to keep the blood glucose at a stable level In doing so, more growth hormone is secreted to promote fat burning & lean tissue retention Resistance exercise also has its anabolic & anti-catabolic effects due to the enhanced muscle protein synthesis. These processes don't really have to take many days, weeks or months. It's a matter of hours. OK, you can call this pure conjecture, but what isn't? Rules of physiology aren't engraved on an ancient stone, and even if they were, some ancient dude like us wrote them there.