Eating behavior is fundamentally driven by two types of impulses. One is hunger, which allows us to recognize when the body has used up or is about to use up its resources and prompts us to make a new “recharge.” Hunger expresses a need. By eating, the need is satisfied and hunger subsides. The other drive is appetite, which is a desire, and it can be felt even when there is no actual need for food.
It may seem strange, but what allows some species to survive is appetite. Some animals, for example, find food only occasionally, so they survive only if they eat everything they find, allowing them to go for long periods without eating by using already-digested reserves. They do not need to eat all that food, but they do so because they have an appetite. If they had only hunger, they would eat a little and only when they were completely “out of” energy.
In humans too, appetite is a very powerful drive. When fasting, hunger enhances appetite, but even when hunger subsides, we continue to consume food. Eating is fundamentally a pleasure, and especially in our society, where food shortages are unlikely, the relationship with food becomes largely a relationship of pleasure. Appetite, unlike hunger, does not subside when it encounters food; rather, it initially increases. As the Italian saying goes, “appetite comes with eating,” whereas hunger subsides as one eats…
Here too, in our society food is available for as long as we want it, so appetite can easily be stimulated.
As with all instincts, it is possible to lose control over appetite, meaning that one may eat beyond one’s intentions and without actually needing to (that is, not because of hunger). If being overweight were viewed positively, and were a source of praise and appreciation, the resulting distress would be reduced. It would not disappear, however, because lack of control is itself at the core of the pathology and generates distress.
In any case, in our society being overweight is a condition that attracts negative comments, or, at best, well-meaning humor. Conversely, being thin, even underweight, tends to attract positive comments: even underweight that does not aesthetically inspire admiration may still generate praise because people assume that someone who is thin is capable of controlling themselves, which is regarded as a sign of “willpower.”
In the past, when hunger was a real threat, being slightly overweight was synonymous with health, beauty, and attractiveness, whereas being underweight was a sign of illness, poverty, and lack of attractiveness. As the social emphasis shifts toward appetite rather than hunger, the cultural model changes as well. Today, control over appetite has become a measure of judgment: those who are fat are seen as unable to control themselves and are therefore criticized; those who are thin are seen as controlling themselves and are therefore praised.
The eating disorders that arise from the relationship between appetite and the environment (food and the cultural ideal of thinness) include:
- Those involving excessive food intake: bulimia nervosa, binge-eating disorder, and compulsive overeating.
- Those involving insufficient food intake: anorexia nervosa.
Bulimia
Bulimia consists of recurrent episodes of excessive food intake, in which large quantities of food are consumed—“everything” that is available—greedily and all at once, often mixing foods in an unusual way.
The person begins binge eating because of appetite, sometimes suddenly (for example, waking up during the night), but it may also be planned (such as stocking up at the supermarket beforehand or taking a bag full of food when leaving home).
The person stops binge eating because the stomach begins to feel painfully stretched, because nausea sets in, or because other factors intervene.
To avoid the “disastrous” consequences in terms of calories—often imagined as a monstrous increase in body weight—or because of shame about having binged, sufferers resort to various remedies: vomiting, taking laxatives, or taking diuretics, based on the idea that losing weight and “deflating” are equivalent, and perhaps because reducing bloating provides immediate relief whereas losing weight would be a slow process.
Other methods may include skipping the next meal, taking products intended to interfere with digestion and prevent absorption of the food consumed, or using products that temporarily suppress appetite and allow fasting for a while.
A person with bulimia may have fluctuating weight or may have a normal weight, and therefore their weight alone may not raise suspicion.
These behaviors are dangerous. Although a binge itself is not necessarily fatal, vomiting, causing electrolyte and fluid imbalances through diuretics, damaging the intestine by interfering with its function, and, in practice, being inadequately nourished because of vomiting and fasting can become life-threatening over time.
Electrolyte disturbances and vomiting are associated with a risk of potentially fatal cardiac arrhythmias. Repeated vomiting can cause tears in the esophagus, with internal bleeding and, in some cases, esophageal rupture. Laxative use can cause atrophy of the colonic mucosa, with a risk of intestinal damage that may be irreversible.
Uncontrolled eating
When there are no actual binge episodes, there may instead be a frequent urge to consume food, to the point of filling the day with more or less substantial eating episodes and making regular meals progressively larger.
The behaviors may indicate a genuine food addiction, with secretive eating, spending money and time obtaining and consuming food, and denial or minimization of the problem.
In this case, body weight increases, eventually leading to obesity.
Anorexia
The person is preoccupied with losing weight. It is not enough to maintain their current weight; they want to keep it below normal or reduce it further.
The person does not question this idea, partly because being slim is socially appreciated and being thin is often considered preferable to being fat.
In extreme cases, the person develops a distortion of body perception, believing themselves to be fat, bloated, and heavy despite an abnormally low body weight, and identifying body mass as an unacceptable “excess” or “fat.”
The abnormality of this condition lies in the person’s strong and seemingly unstoppable ability to suppress appetite, while continuing to exercise even as the caloric balance becomes increasingly negative.
The weight of a person with anorexia decreases, with various consequences. In women, a typical sign is the interruption of the menstrual cycle.
A person with anorexia often hides their condition so as not to be prevented from pursuing it, believing that it is nevertheless “worth it” regardless of the risks.
Anorexia is also a term used in everyday language, where it may simply mean “being thin” or “having no appetite and not eating.” Anorexia nervosa, however, is a disease in which the problem is not simply having no appetite and therefore not eating and losing weight, but having an extremely strong motivation to lose weight without limits, resulting in increasing withdrawal from food.
In reality, the same disorder may pass through different phases, involving food restriction and binge eating, often while maintaining a persistent preoccupation with body weight and certain behaviors aimed at preventing weight gain or promoting weight loss (for example, vomiting in bulimia, or restricting food intake or exercising in anorexia).
This gives the impression that, at least in some cases, anorexic phases represent such strong control over food that appetite and hunger are suppressed, whereas bulimia represents an inability to control appetite.
A disorder that begins with anorexia tends, like an elastic band being stretched, to increase appetite, so that at a certain point, either intermittently or for periods of time, appetite prevails and binge episodes occur, followed by compensatory behaviors.
Conversely, a disorder that begins with excessive food intake may later pass through a phase of excessive control, accompanied by significant weight loss.