Some things are within our power, and some are not. Within our power is opinions, beliefs, values, the power of assent or rejection, some aversions and attachments, delusions and illusions. Most other things are only under our influence, nothing like control, and much is totally beyond the influence of anyone. So we can only have free will over those things that we have control over. Note that our body, at best we have some influence over but nothing like control. Our mind cannot influence our genetics, or our epigenetics much. Over extended time we can turn on or off some characteristics when we are young, before we have anything like mature reasoning ability. Those early decisions can screw us for life.
Epigenetics control our desires for food at a cellular level. When the demand is turned on through overeating, we are harnessed with that desire for life; it is no longer anything like free will. That is why sustained weight loss through diet is only successful long term in 5% of the population. We need to fight our very nature for the remainder of our lives or accept obesity. We do not have free will in this matter. We have a natural desire at a cellular level to eat. Anyone who says lifestyle knows less about this issue than I. Yes, I have confidence in this fact. The research is elsewhere.
AA, NA, OA, etc work by the creation, in the mind, of a divinity that is more powerful than the problem, submission to this divinity, and following the directions of this divinity and other "suggestions." It is not rational. When/if we are unable/unwilling to create this delusion in our mind, those programs are unable to provide any help other than "just do it because it works." So what is the rational approach to overcoming our nature? Well that is where things get really scarce. There are "tool systems" and education, and knowledge, but mostly it is unknown. We are exploring for the devil, as if there was one.
So what is stronger than our nature? One thing is obsessive compulsive behaviors. So is it possible to train in limited obsessive compulsive behavior in the self?