Knowing what one should and should not eat is one part. The much more difficult part is doing, eating well, but not overeating. That is the essential issue for most overweight people, yet there is little beyond generic motivation that deals with the problem.
Everyone I ever met who was overweight wanted to be lighter, some even became lighter for a time. It is giving up the drive to eat that is so difficult. It is that philosophical / individual thinking area that I need to study a bit more. There are two areas, external outward looking, (humanism) and internal inward looking (stoic world view) to rationalize. Much of this is to take one concept at a time and decide how I actually believe about that subject, the reasons for such a belief, and examine my consistence of thought and behavior. Doing what seem natural has not worked in respect to food, and I expect that this is due to epigenetic encoding.
As I look around at the people, I realize that much of our population is likely dealing with this encoding problem, but is unaware of the exact cause. Developing OCD with respect to food intake is one method of recovery, but that is a bitch to live with as well. Redirection is the other, and that requires light work that we enjoy as well, which is also effort.