Humans developed as animals first, then became more intelligent, developed technology, specialization, and all the great things we are today. With specialization comes ignoring earlier knowledge to make room for learning current knowledge. Was weight control one of those areas that was forgotten?
We are not our minds, and our minds are not us. Our intelligence does not control us, only influences our choices. Ego is a construct of the thinking mind, often for our protection. Ego exists both positively and negatively, it makes us better than our fellows and less than, but either way it is a function of the thinking mind, and can be modified to closer to what it should be rather than allowed to run free. We can do this by watching the arising of emotions, thoughts, cravings, and the like, before we react to the situation.
The forgoing is the reason that meditation works, but it does slow down the thought process. Notice that most mediators think and speak slower. It takes time to watch, filter, evaluate before we do something. Note that in the Buddhist tradition, speech must be true and beneficial before it is spoken. That sure cuts out a great deal of garbage.