Feeding Behavior and Body Mass Index

Abstract

Due to the tens of millions of years of evolution with food shortages and famine, the human body has been extremely well conditioned to force physiology and behavior to take in as much energy as possible from the environment, and when energy is unavailable, to spare. These characteristics have allowed mankind to survive in spite of resource shortages and to populate the planet. Mechanisms which waste energy or limit food intake do not work or exist, and in environments with ample food sources and which do not require physical labor (such as in western developed countries), people have difficulties maintaining a healthy weight and tend to gain weight. According to the bioenergetic model, the human body can accumulate great amounts of energy even with nearly imperceptible increases in food intake, strongly compensating the energy imbalance limiting weight loss. Furthermore, there are driving behavioral factors which compel one to eat when food is available for the purpose of accumulating energy for emergency needs. From this perspective, it is apparent that a peculiar eating pattern leading to overweight or obesity does not exist, and that in predisposed individuals obesity can develop without significant changes in eating habits or behavior. Cognitive restraint describes the subject’s efforts to limit food intake in order to lose weight or avoid weight gain, and this attitude is frequently observed at high BMI levels and should be regarded as a consequence of the obese status. The tendency toward disinhibition over food intake is associated with high BMI levels, and may play a role in the weight gain process and/or in the maintenance of overweight or the obese status. The disinhibition, or opportunistic eating, could represent a behavioral mechanism conditioned by natural selection against food shortage and in an environment dense in food stimuli might give rise to emotional distress. Night eating is an eating pattern which is not yet well-defined which may lead to overeating and to weight gain in a manner that is different from disinhibition. Feeding patterns that are commonly associated with obesity simply favor the increase in food intake and/or are simply a consequence of the obese status. In perspective, the fight against obesity as a social disease must be focused more on the environment than on individual behavior.