Hunger and Fullness

Hunger and fullness are the internal cues we use to regulate eating. They are also what our current culture of abundance of food and obsession with thinness looks to exploit. Last, they are what goes awry in an eating disorder. Relearning these cues is a cornerstone of eating disorder treatment.

At the most basic level, hunger is critical to our survival. It is clear that identifying hunger and acting on it is necessary to avoid starvation and death, both as an individual and as a species. Most of us feel mild hunger on most days, but hunger need not be a regular part of daily life for a majority of the population anymore. Experiencing hunger seems more like a social statement--or even a medical condition--than an evolutionary necessity. But forced hunger and starvation are very different. Prolonged hunger leads to a primal, visceral response which includes obsessive thoughts about food, a voracious ability to eat endlessly, cravings for odd food combinations, mindlessly performing strange food behaviors and a complete loss of rational thought around the social norms and propriety of eating. In other words, anyone who is chronically starved exhibits the symptoms of anorexia nervosa. This point highlights another curious aspect of eating disorders. Anorexia looks more like an adaptive mental state in starvation than a psychiatric illness.

It is less clear what role fullness, or satiety, plays in our lives. Historically, eating until one was full, very full, was looked upon as socially correct behavior. If there was an erratic food supply, eating a lot was a way to store energy for the future. Eating large amounts and gaining weight was a sign of prosperity and wealth. The expression of love and caring in many cultures is through providing food and eating together, usually to excess. Similar to anorexia, overeating or binging looks like an adaptive response to an environment with excess resources: eat and eat and eat. It is a physiological response to help avoid hunger in the future.  Calling it a binge is a new classification of an old, adaptive behavior. Any compensatory action to repair the "damage" done by the binge, i.e. purging, are panicked responses to the social judgment and perceived consequences of the binge. Fullness has no clear relevance to survival. There has been little reason to hone our instincts to identify fullness, at least until now. Bombarded with a neverending supply of food crafted to appeal to all of our senses, fullness is now necessary to avoid overeating and obesity. In that vein, fullness is not adaptive at all. It is a social construct created because of our ideal of thinness and a culture serving up endless quantities of food. Our society acts as if fullness is a natural instinct, and by extension a failure for those who cannot recognize it, not an ingenious way to place responsibilty for the obesity epidemic upon the individual.

Like all adaptive, evolutionary traits, hunger and overeating are exhibited along a spectrum. Some people will experience the starvation response more quickly and profoundly while others can tolerate hunger and function. Some will gorge around excess while others will not be capable of overeating. From an evolutionary standpoint, this variability within a population ensures the survival of a species. Certain people will survive in famine and others will prosper in times of excess. In modern times, these traits transform from evolutionary traits into eating disorder risk factors. Suddenly, people who can withstand hunger try a diet and find that their tolerance for hunger is rewarded by society and by the internal, visceral high of starvation. Others who have the adapted trait to overeat when food is abundant find that the food industry products trigger a primal craving, such as sugar cravings or carbohydrate cravings. In our current culture, it is a short leap from evolutionary leanings to a full-fledged eating disorder.

If risk factors for an eating disorder are adaptive traits, where does that leave those most susceptible? If we live in a world with food aplenty and processed food designed to appeal to our most basic desires, how can those susceptible not get an eating disorder? How effective can intuitive eating--a treatment designed to help us get back in touch with our internal sense of hunger and fullness--successfully compete with evolutionary adaptations? These are sobering thoughts. They leave eating disorder treatment in a bind between our most basic instincts and the missteps our society has made about how we handle food.

Although I am tempted to address the larger picture first, I want to stick with the original point of writing this blog: the treatment plan. So the next post will look at the transition from adaptive response to eating disorder. As I described in the last post, it is called the prodrome.

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