My brother is a shitlord in residency at medical school, and he told me starvation mode does in fact exist, however you have to be expelling a shitload more calories than you take in. E.g., you're running 10 miles a day for 2 weeks and eating 600 calories a day for those two weeks. If you eat large amounts of food after that, it rapidly gets stored as fat instead of carb stores.  Fatties "learned" about starvation mode and now think if they don't eat 7000 calories a day they're gonna go into starvation mode and gain even more weight.  I exercise a lot and eat about 1800 calories a day and I've had no problems with "starvation mode", because it really doesn't exist except in extreme situations.