This has more to do with hunger requiring a tremendous amount of willpower to ignore rather than fat people having less willpower than people of average weight.
I also know that if I overeat, I have a strong urge to keep feeding (more chips, more pizza, more chipsahoy). Whereas when I eat a proper meal, I'm fine when the eating of that meal ends.
Kids often still need to learn that punching yourself in the face hurts.
While at a certain level of abstraction you can reduce both to A -> !B -> C, that generalization seems to obfuscate specific important differences that impact pathways to treatment. Craving is not the same as lacking energy. Craving, while subversive, energizes, depression does not.
The only thing that helped my depression, apathy and executive dysfunction was realizing I was going to rot anyways, I was never going to be happy, so I may as well start the startup, go on runs, and succeed.
Let go of the expectation you will want to/be in the mood or feel good from it
Life is not chocolate malts and gummy bears