What Is Set Point Weight?

Medically Reviewed by Michael Dansinger, MD on May 21, 2023
4 min read

The hardest part of losing weight is keeping it off. Research supports this conclusion. Some scientists believe that the human body has a set point weight that it returns to. If you lose weight, your body may work to put it back on.  

Although there is evidence for the set point theory, other factors in weight loss are important too. And studies show it is possible to lose weight and keep it off. 

Set point theory states that the human body tries to maintain its weight within a preferred range. Many people stay within a more or less small range of body weight throughout their adult life. Some people's systems may keep them lean while young but allow them to gain weight after middle age.

In set point theory, if you suddenly start eating fewer calories, the way your body burns fuel (your metabolism) will slow down. You will burn fewer calories even if your activity level does not change. Your body may also change the way it absorbs nutrients. Your hormones could change and make you hungrier. These factors could make it easy for you to put weight back on. ‌

The idea of a set point weight is just a theory because there is no real proof. Researchers have observed that many humans return to a certain weight range, but scientific studies of weight are difficult. It's hard to control what human subjects eat. Instead, most studies rely on self-reporting, which can be inaccurate.  

If your body helps you regain weight that you have lost, shouldn't it help you lose weight when you gain? If we have a system that regulates body fat, why is it so easy to put on pounds? Scientists have worked to answer these questions.

Biologists say that throughout history, starvation has been one of the greatest threats to humans. Our bodies developed a way to protect us against starvation by holding onto fat. Only in recent years has obesity become a health threat. Possibly our bodies have not yet evolved to address that challenge.

Reducing the calories you eat triggers several changes in the body. Some of these changes make it hard to keep weight off. 

Lower calorie burn. Having a smaller body means that you use fewer calories. You may have to cut your intake again in order to keep your weight from returning. 

Hormonal adjustments. Your levels of leptin may go down. Leptin is the hormone that makes you feel full. You may have to eat more to feel full. You may experience rises in ghrelin, the "hunger hormone." Your appetite may increase.

Focus on food. People who restrict calories often think about food more often. Research suggests that their sense of smell may be enhanced. When food smells and tastes better, we often eat more. 

Set point theory can't explain several patterns of weight gain that scientists have observed. These patterns suggest that what's going on in a person's life may be as important in determining weight as the body's set point. Scientists have seen that:

  • College students often gain weight.
  • Children who watch a lot of television are more likely to be obese.
  • People often gain weight after marriage.
  • In Western countries, less affluent people have higher levels of obesity.
  • People often become heavier after moving from Asia to the West.

We may be able to learn more about set point weight by studying people who have had weight loss surgery. Does the surgery change their set point so that their bodies are "happier" at a lower weight? 

Weight loss often triggers slower metabolism and larger appetites. Some researchers say that weight loss surgery does not seem to have the same impact. Scientific studies in humans are lacking. One animal study supports the theory that weight-loss surgery could change the set point.

Even if set point theory is correct, losing weight and keeping it off is possible. Avoiding fad diets and losing weight slowly may change your set point. It may give your body time to adjust to your new way of eating. You may be more successful if you get help from a therapist or dietitian.

Recent research shows that about 20% of dieters keep the weight off. The National Weight Control Registry tracks people who have lost at least 30 pounds and have kept it off for at least one year. These individuals regularly answer questions about how they keep the weight from coming back.

The data so far shows that people are more successful with long-term weight loss after a "medical trigger" — a warning about their health. Also, 

members of the registry practiced these behaviors, which may be tied to keeping weight off:

  • They weighed themselves regularly, often daily.
  • They attacked small weight gains before they became large gains. 
  • They ate breakfast, often cereal and fruit.
  • They exercised around an hour a day, often by walking.
  • They ate a low-calorie, low-fat diet.
  • They were consistent in sticking to their eating plan, even on weekends and holidays.

People who regain weight often blame a lack of willpower. Researchers have found that willpower plays a role in weight control, but that role is relatively small. Other factors are more important.