[tsol]

Your body can speed up or slow down processes to conserve energy. For example, it's much easier to lose weight when you are heavier versus if you are skinny because your body is quicker to slow metabolism. And that is just one factor. Gut microbiome is another.

[adamdusty]

Sure your body could put itself into a coma and conserve all possible energy, and it would still be physically impossible for it to store energy you did not consume.

Your body will never go under such heavy energy conservation that you cannot lose weight, and it doesn't have enough control to do that anyway. At best your body can attempt to slow down your physical activity and slow down digestion for efficiency. Yes as you diet your metabolic rate will decrease, and even if it were to decrease an impossible amount like 50+% you would still be able lose weight by comsuming less energy.