I doubt you’ve ever stood in front of the refrigerator at night thinking, “Let’s see…which micronutrients do I need right about now?” But of course, as with all living things, we need nutrition to keep our organs functioning and, well, stayin’ alive. So the first and most obvious reason to eat is for the basic fuel to keep going, even though we’re not actively thinking about it. What we do experience and are frequently conscious of is the other biological reason to eat which is hunger.
Hunger can be seen as a sort of bridge between biological needs and psychological needs. It is at once a physiological response to the stomach being empty, as well as a motivational state to get you to eat; and these two aspects of hunger work together adaptively. It may seem self-evident but the reason we experience the hunger response when we do is not so obvious. Think about it: Why do we have a signal of discomfort after only about four hours of not eating even though our health is not substantially affected by it for at least seventy-two hours? Even then the effects are reversible. Hunger strikers have survived up to two months or more without food. There is a very long way to go from hunger to malnutrition and then to starvation and death. So why is having an urgent early warning system a useful advantage for species survival?
It is probably not news to you that our bodies were not adapted for grocery shopping. We have the same bodies that were well-adapted for an environment where food was usually scarce and hard-won. In order to do the work necessary to score a meal in a pre-modern hunter-gatherer society, one had to be fairly strong and highly motivated. Someone who was well-nourished and satisfied may not have felt especially driven to risk his life on a hunt or have had the foresight to put forth the physical effort to plan for the week’s food supply. If, however, he experienced a hunger signal that was sufficiently intense and uncomfortable, the motivation to obtain nutrition will motivate him while he’s still strong, even long before the need for food becomes critical to survival, making success and survival more likely.
This is also consistent with the fact that, paradoxically, as food deprivation continues, the hunger signal eventually shuts off completely. Once the body recognizes that the calorie deficit it’s experiencing isn’t due to a lack of motivation to hunt but rather the absence of food to eat, the painful hunger signal is unnecessary.
The second good reason to eat is social convention. Throughout human history and continuing to this day, food has been the center of cultural and religious ceremonies, festivals, and family gatherings. Historically, people would make a feast as a way of giving thanks, and even today we have many social rituals that involve particular foods, like eating cake at a birthday party, popcorn at a movie, or a hot dog at a July Fourth picnic or baseball game.
These traditions and religious rituals often determine when, what, and even how much to eat. Of course, it serves the purpose of satisfying hunger, but even when hunger is not a primary motivation, it is often considered socially unacceptable not to eat. Just think about turning down a serving of turkey, mashed potatoes or candied yams at Grandma’s Thanksgiving dinner to get a sense of what I mean. It’s all part of belonging to a social group, and it usually doesn’t take much to fulfill your obligation.
The third healthy reason to eat is simply the desire to experience the satisfaction of enjoying a favorite food. Eating something you desire for no other reason than the pure pleasure of the experience is a perfectly valid motivation to eat. It is the only reason to end a meal with dessert, which almost by definition is not intended to satisfy hunger or nutritional needs.
Not only is desire an acceptable reason to eat, but fighting against the natural impulse to eat for pleasure sets up a psychological process that could lead to a counter-reaction of eating to satisfy the sense of deprivation rather than genuine desire for the food. This rebound effect is a theme that I will return to as a central point in my approach to treating emotional eating. The key is to be aware of the point at which the original desire is satisfied and eating beyond that is simply a mindless force of habit.
The pleasure we get from eating is just as much of an adaptive mechanism as hunger, since it provides a positive motivation to seek out food (as opposed to the negative motive of avoiding hunger). The problem occurs when, in the context of food abundance, this once adaptive response is seen instead as an indulgence and a weakness that must be controlled by sheer self-discipline, which makes no more sense than using willpower to ignore the hunger signal itself.