Is the Set Point Theory a Fact or a Myth?

Is the Set Point Theory a Fact or a Myth?
Does Your Body Have an Internal Thermostat That Regulates Fat?

By Jennifer R. Scott | 
Reviewed by Richard N. Fogoros, MD
Updated July 11, 2017

Set point theory states that
the body maintains its weight and body fat level 
with internal regulatory controls.

According to the popular theory,
some people have a high setting,
meaning they tend to have a naturally higher weight as a set point,
while others have a low set point and
therefore a naturally lower body weight.

The Set Point Theory Definition

If you've tried to maintain weight loss after slimming down,
you can probably understand the idea behind an internal set point.

The set point definition simply states
that your body will fight to maintain a given weight,
even if the weight is too high.  
So no matter how hard you try,
you can't seem to keep weight off after sticking to a diet and exercise plan.

People who believe in the set point theory believe
that your body has an internal "thermostat"
that regulates body fat.

If your thermostat is set high,
then you are destined to carry more fat
—even if you try to lose it with diet and exercise.

But if your thermostat is set low,
then you are probably going to be lean for life.
The theory may discourage some people
from making exercise or dietary changes
to lose weight.

Evidence Supporting the Set Point Theory

If you believe the set point theory,
you may see some evidence that seems to support it.

• Weight loss lowers metabolic rate. 
  Some studies have shown that 
  your metabolic rate decreases after you lose weight.
  And some researchers believe that
  it slows down to a rate lower than
  that of a similar-sized person who has never been overweight.
  That means that a formerly-obese person has to eat less or
  do more daily exercise to maintain the same body size.
   

• Ghrelin increases after weight loss. 
  The hunger hormone ghrelin increases after you lose weight.
  Ghrelin has many functions in the body
  but one of them is to make you feel hungry.
  People who have lost weight usually have higher levels of ghrelin,
  so their bodies are telling them to eat more often.
   
• Exercise needs increase after weight loss.
   The American College of Sports Medicine recommends that
  people should get 150 minutes of exercise per week
  to maintain good health.
  But people who are trying to lose weight or maintain weight loss
  should get 250 minutes or more
  to slim down and keep the weight off.
   

• Thousands of stories from dieters. 
  The best argument for set point theory is that
  many dieters struggle to keep the pounds off. 
  Any dieter can tell you that
  keeping your body thin after weight loss is nearly impossible.
  And weight regain statistics agree.
  Nearly 80% of dieters regain weight within a year after dieting.

Is the Set Point Theory a Myth?

While there is some disagreement about the validity of set point theory,
researchers find that there is something to it.

Fortunately,
set point is not the same thing as destiny.

According to the Beth Israel Deaconess Medical Center at Harvard:
 "Your heredity and your environment,
starting back at the moment of your conception, determine your set point.
Over the long term,
excess food and insufficient exercise will
override your body's natural tendency
to stay at its set point and lead to a higher,
less healthy set point."

There's no doubt that
trying to keep the weight off for good is very hard.

But there is a combination of factors
that contribute to the difficulty.

These might include your social environment,
food habits, and genetic or hormonal factors.

If you're trying to stay slim,
your best bet is to ignore the set point theory
and instead work with your doctor, your dietitian,
and your support system to stay active, make smart food choices, and keep your body healthy.

Sources:

Beth Israel Deaconess Medical Center. The Science of Set Point. Web. 2017.
Karasu, S. A Point of Reference: Weight and the Concept of S​et Point. Psychology Today. February 2015.
Müller MJ, Bosy-Westphal A, Heymsfield SB. Is There Evidence for a Set Point That Regulates Human Body Weight? F1000 Medicine Reports. 2010;2:59.