Couldn't be either, because:

(1) If you're lifting weights (on a progressive resistance plan) and eating enough protein (1g per day per pound of lean mass - that's a lot) and enough carbs and eating a calorie surplus and have the testosterone of a 20 to 30 year old man, you'll build up to 1/2 pound of muscle per week.

(2) That doesn't happen. All throughout history, when prisoners of war aren't given enough to eat, they always lose weight as a result. Starvation mode is a popular diet myth, but it's a myth. It's true that as you lose weight, you need fewer calories to maintain fewer pounds. But that's a different thing than saying your body just prefers having extra weight and will maintain it without resources.