On one hand, the science behind weight loss couldn’t be simpler: calories in, calories out — eat less and move more. On the other hand, it’s as complex as the human body itself. Weight gain, and what happens to your body when you lose weight, is affected by a constellation of factors:
- Diet
- Genetics
- Energy expenditure
- Hormones
- Environment
- Stress
- Your body’s natural defenses
One of those defenses is known as the “set point,” a theorized baseline that’s understood to affect weight loss and maintenance. Learn more about set point theory, how much faith to invest in it, and what — if anything — you can do about it.
What Is Set Point Theory?
“Set point theory asserts that there is a weight at which our body is most comfortable, determined in part by genetics, body size, and metabolism,” says Dana Hunnes, Ph.D., MPH, RD, a senior dietitian at the Ronald Reagan UCLA Medical Center. “This set point will differ from person to person, just as genetics differ from person to person.”
While body weight — and who has more, and where, and how much, and why — is still largely a study of unknowns, set point theory argues that it may be heavily affected by the body’s tendency toward the familiar. Furthermore, according to set point theory, your body will “fight” to stay at the weight at which it is most comfortable.
“This means that if you go on vacation, eat a lot more than you normally would, and gain five pounds, once you return to your normal routine, your appetite will decrease to adjust, and you’ll likely return to your previous weight,” says Hunnes. “Similarly, if you diet and eat a lot less for several weeks, eventually your body will fight back, increasing appetite to make you eat more, and you’ll likely return to your prior weight.”
Is Set Point Theory Legit?
Set point theory is certainly nothing new — researchers have been investigating it for decades. And the consensus is that there’s something to it.
A review of studies published in the Journal of Metabolic Syndrome and Related Disorders found that body weight is generally maintained at a stable range, despite variability in energy intake and expenditure, showing that obesity is likely a result of a complex relationship between genetics and environment.
Hunnes says: “It makes a lot of sense. Our bone structure, genes, and metabolism all tend to like homeostasis, or relative stability. Our bodies work best when things are stable. So yes, I believe we all have a set point.”
It’s not as rigid as you think
Set point theory is not, however, a reason to feel powerless or that you’re genetically predestined to stay at a weight you’re not happy with.
“Studies suggest that a set point in humans is ‘loose’ (e.g., involving upper and lower limits) rather than tightly controlled,” says a review of studies published in the journal F1000 Reports.
Set point theory is based on evidence from time-tested, expert weight-loss advice: gradual and stable is best. Make it part of a long-term lifestyle change based on regular diet and exercise.
Don’t try to lose weight with workout binges or starvation and fad diets — people who do that tend to gain the weight back, often adding even more; their body’s set point might be part of the reason why.
Can You Change Your Body’s Set Point?
Yes, but the change should be gradual.
“I think it is possible to ever so slightly change your set point,” says Hunnes. “If you crash diet, you will not change your body’s set point and may run the risk of increasing your weight in the long run. If instead you’re slow and steady over time, you may create a new set point for your body.”
Hunnes uses herself as an example. In high school, her body’s set point hovered around 125 to 128 pounds. “No matter what I did, [my body weight stayed in that range],” she says.
Years later, she has a Ph.D. in public health and pursues a career as a dietitian, and “not necessarily intentionally,” her body homes toward 118 to 120 pounds. Hunnes says that could be because she started eating a plant-based diet as an adult, or because parenthood has made her more active.
“No matter how much or little I eat, or how much or little I exercise, I tend to remain in that range,” she says. “Little changes or adjustments over time may be able to slightly change the set point. But if you are big-boned, you cannot expect to be a small and thin person. It just won’t work that way.”
Set Point Theory for Weight Loss
“The best way to lose weight effectively will be with very small, incremental changes that perhaps fool the body into thinking it’s still in maintenance mode,” says Hunnes. “If you cut out 100 calories from your ‘typical’ food intake for several months — meaning that instead of eating 2,100 calories a day to maintain your weight, you eat 2,000 and perhaps burn a bit more energy every day — your body won’t really ‘notice’ the change, and you should theoretically slowly and gradually lose weight.”
By creating a slightly larger calorie deficit and incorporating regular exercise, you can avoid weight gain and achieve more weight loss. But experts say it should be gradual, aiming for one to two pounds a week, to keep your metabolic rate stable.
“Slow and steady wins the race,” concludes Hunnes. “Slow and steady can keep your homeostasis in place.”