Motivation is required to lose weight. We need to "buy in" at the emotional level, know the why at an emotional level, or deeper. Some say that we need to "believe the why" to maintain motivation, and that why must be very dear to us. In a way that makes scene, as to lose weight required more motivation that our body's desires to eat. Enough motivation to overcome primordial urges. OK.
Those who do not acknowledge this basic fact have never worked through a substantial weight loss. Weight loss changes our interests, ever personality. Ask Jimmy, Micheal, or any of those other 100 pound plus losses if they are the same person as before. Perhaps, the change must come first, I do not know.
Spiritual level is even deeper than the emotional level, hence this may be the solution. That is to say that it is required to have a belief that we can and should be about normal weight. Carnegie refereed to these an noble motives. At the same time, we need to note that emotions are part of our ego, so beware of ego building.
When we consider Maslow's proiority, food is a basic, but survival trumps that.
How do our spiritual beliefs tie into all this? I an not sure, but that is one more in the list of contributing factors in diet, or one of the multiple causes of obesity.