Assuming you are a fan of evolution -- and not all are -- why would humans have such a complex and multi-faceted relationship with feeding ourselves if not for survival of one's genes through famine? If finding food was as simple as reaching up and having it, grazing through a field of adequate nourishment, our hunger drives would be pretty simple. Yet we have terribly complex and multifaceted systems to help us seek, choose, refuse, and feel sated by food. Only one system has to go down to make the others go awry as well.
Intermittent famine is the threat that humans have faced and survived most often, and we are well-adapted to it. We're not all that adapted to turning down food, and I have no doubt any more that the turning down of food opportunities is doing serious harm:
- It sets up moral and anxiety-based relationships with foodstuffs: we have good foods and bad foods to choose from, and our morality and intellect are judged by those choices.
- It creates "dieting," an artificial and unhealthy intermittent famine. This self-imposed famine condition sets us up for internal forces built to fight a lack of food: compulsive food-seeking, a melting of social connections, a messianic value to restriction.
- For some it breaks the development of normal social eating and intuitive feeding behaviors.
- Others suffer by setting off a genetic cascade of thoughts and behaviors that make normal eating nearly impossible.... something we now call an eating disorder.
For those interested in this idea, look into Shan Guisinger's Adapted to Flee Famine hypothesis. Worth a read.