Deep Dive: What happens when you eat as much as possible?

Obesity is the result of a chronic positive energy balance, in which more energy is absorbed than expended. Part of the problem with the current approach to mitigating obesity, besides the fact that it is a multifactorial disease, is determining why some people, but not all, overeat. Although it is pretty well agreed upon^[1] that over consumption of food is the result of many factors, studies have shown^[2] that people normally tend to compensate for overfeeding periods and lose the weight gained afterward in an unconscious manner. Understanding the differences between people who can and people who can’t compensate requires a careful examination of the physiology of overfeeding.

There have been many studies over the years testing different types of diets for weight loss, both under very controlled conditions and under free-living scenarios. However, the physiological response to maximal overfeeding (i.e. eating as much as possible) has received comparably less attention. Moreover, most of the previous long-term overfeeding studies^[3] have analyzed the effects of prescribed overfeeding, in which participants are given a specific energy intake goal that is above their energy requirements. So, it is not known precisely how the body deals with maximal eating and the physiological responses to it.

The authors of this study wanted to compare and characterize the acute participant response to two types of feedings: participants eating until they were comfortably full and participants eating as much as they possibly could.

Obesity results from the chronic overconsumption of calories, which is caused by several environmental factors. However, normal weight participants appear to compensate for overfeeding, so it is not completely understood why some people do not compensate for an increase in energy intake over time. Moreover, the physiological response to eating as much as possible has not been yet determined.