No science to back this up but I would suggest that we do burn fat and muscle fast to lose this much weight in such short a time. My explanation is based on my body temperature being so high, and being awake. When I'm flaring, and sometimes even when I'm not, my body temperature is toasty, and I'll be sweating for no good reason - I believe this is the inflammation, or my body working hard to fight it. Since I usually can't sleep, even if I'm in bed I am tossing and turning. Sometimes my sheets will be soaked. And whatever fat I had before the flare quickly becomes noticeably absent, bones protruding and sunken cheeks etc, muscles depleted. It's the only explanation for losing so much weight so quickly, based on my observations. Which also makes it difficult to gain it back again! Just my 2 cents...