The set-point theory describes the regulation of body weight. According to this theory, every human being has a specific body weight that makes him relatively well, and which is kept constant by the metabolism under normal conditions. The height of this individual weight is called set-point. Its exact value is probably innate and can not be significantly influenced in the long term or in the long term without health problems. This means that the body strives to maintain its normal starting weight - the set-point.
Weight settles down
A short-term weight loss under the individual set-point weight is possible, but the weight shuttles in the long term towards the starting point. It comes to a counter-regulation, which counteracts an excessive weight loss. The same principle also applies to the opposite direction: following a high-calorie "mast cure", special changes in the metabolism occur so that the former, normal starting weight (set point) is reached again over a longer period of time.
The findings about the set-point are not new. Already in the 50s and 60s, scientific studies on the effects of weight loss or high calorie diet on the body weight and the condition were carried out. Some of these investigations are still considered classic today.
Studies on set-point theory
Probably the most important study was carried out in 1950 in the USA by the working group around Keys. The aim of the study was to investigate the consequences of starvation on mental and physical well-being. The study was attended by young, mentally healthy men of average weight. The entire study duration was one year.
During the first three months, the men fed normally, according to their previous eating habits. In the following six months, the actual diet phase, the individual calorie amount was halved. Under this calorie reduction, participants lost an average of 25 percent of their body weight. In the last three months of study, the participants were getting more and more to eat again and gradually gained weight again.
Even healthy people change behavior
The results showed in addition to the weight change surprising deviations in the behavior of men: During the diet phase, they were increasingly mentally busy with food and could concentrate less and less on other. This was true not only for topics of conversation, but also for reading material. Some started reading cookbooks and collecting recipes. They spent a lot of time worrying about upcoming meals. In part, participants spent hours eating a meal that they would have needed just a few minutes earlier.
They also experienced large mood swings. Most were irritable and nervous, many were depressed. They lost interest in social contacts and increasingly withdrew. The ability to concentrate and view decreased significantly.
Feeling lost for hunger
The same thing happened with the physical efficiency. Many have experienced sleep disorders or gastrointestinal complaints. The basal metabolic rate and thus the energy consumption of the participants was reduced by about 40 percent. Therefore, the men lost less weight than expected due to the calorie reduction.
During the diet phase, binging occurred for the first time in the men, which people were ashamed of. The normal feeling of hunger, satiety and appetite came to the most completely lost. These problems persisted for a while after the diet was over. In the final phase of the study, the participants regained weight and regained their initial weight.
What causes weight gain?
Another important research question was the extent to which the weight of a person increases by a strong increase in the daily calorie count and the consequences for the mental state. This study was carried out in 1968 by the American research group Sims. 15 men increased their weight by 25 percent within six months. Initially, most participants easily gained a few kilograms.
However, this changed in the further course: only four men increased significantly by the over-nutrition (maximum of 10, 000 kcal per day). The remaining participants had to work hard to gain more weight and eat a lot over large meals in order to gain sufficient weight. Under the condition of a high-calorie diet, the basal metabolic rate of participants had increased significantly.
Starting weight after overeating
That means the metabolism consumed more calories, producing more heat and sweat, for example. For this reason, the observed weight gain was limited and less than expected due to the calorie intake. Three participants had not achieved the goal of a 25 percent weight gain by the end of the study.
After overeating the majority of the participants quickly decreased again and reached their initial weight. Only two men remained overweight; Both had a family history of being overweight and they quickly and easily increased from the beginning of the study.
Conclusion: set-point theory
The results confirm the set-point theory, according to which the individual body weight is for the most part biologically determined. Diets are not a permanently effective weight-regulating method, as specific metabolic mechanisms counteract the diet and "defend" the set-point. That is, the weight is stabilized at the level of the initial weight.
Irregular eating, fasting, vomiting, binging, and the use of laxatives or appetite suppressants, as a combined effect, have a significant disruption to the usual feelings of hunger and satiety. Therefore, even in previously healthy people (with normal eating habits) as part of a highly calorie-reduced diet, all the features of anorexia or Essbrechsucht occur.