If you haven’t heard the term set point weight (SPW) theory yet, chances are you’ll be hearing a lot about it soon enough. Set point weight is just the latest discovery from recent diet studies suggesting a person’s weight is a poor indicator of one’s overall health and mortality. It’s believed SPW, like somatotype, is highly influenced by genetics and, therefore, behavior changes rarely have a positive impact on it. Worse, the studies seem to indicate dieting increases one’s SPW in the long term.
What is Set Point Weight Theory?
Set point weight is a scientific theory that humans are each uniquely, genetically coded with an ideal body weight and body fat percentage. This coding developed out of necessity for human survival during hunter-gatherer times, when humans would cycle through food abundance and scarcity. During scarce times, the body’s metabolism would slow to preserve energy until such time when food was more readily available. When food became available, the genes would trigger hunger hormones while maintaining a slower metabolism. This met energy needs in the short term and encouraged the body to store excess as body fat to return to before scarcity weight (SPW) to ensure he could survive the next food shortage.
This theory may also explain why SPWs might vary among cultures as food sources and dietary needs differed depending on where they lived on the planet. Consider differences in food sources and daily caloric expenditures between people living in equatorial regions compared to those living within the Arctic Circle. I suspect this phenomenon might explain how somatotypes originated and why different somatotypes have varying hormonal responses to diet and exercise.
Even though Western societies are hundreds of years beyond the British Agricultural Revolution, it’s believed the genetic adaptations that occurred to protect human survival were thousands of years in the making and remain hard wired in our DNA to this day.
This means any diet that restricts calories to force weight loss triggers the SPW response. The decades of statistics showing a majority of dieters regain weight loss within five years led scientists to develop this theory. Additionally, scientists hypothesized DNA might also be responsible for the weight-loss plateau most dieters experience after an initial rapid weight loss, even if further calorie restrictions and increased exercise measures are employed.
Unfortunately, scientists who have tested this theory have not only discovered a genetic SPW likely exists but that traditional dieting exacerbates the situation. Here’s a hypothetical dieter, Susie, to illustrate the theory:
- Susie’s weight: 150 lbs (height: 5’5″); daily calorie intake to maintain current weight: 1800
- BMI chart places Susie in the Overweight range
- Susie wants to lose 20 lbs to be in the midpoint of the Normal range on the BMI
- Susie embarks on a diet and exercise program with a daily calorie deficit of 500 (1300 total calories daily) until she reaches her goal of 130 lbs.
Assuming Susie maintains the calorie deficit until she reaches her goal, she cannot return to an 1800 calorie diet to stay at 130 lbs. Susie has actually trained her body, by slowing her metabolism, to maintain her weight on less than 1800 calories daily. When she returns to an 1800 calorie diet, even with diligence and regular exercise, her body will burn the minimum for daily life and store the rest to achieve her SPW of 150 lbs (or more). But, odds are against Susie even reaching her weight goal to begin with because, as soon as she begins restricting calories, the SPW genes kick in hormonal responses that affect hunger, satiety and metabolism to maintain the SPW at all costs.
In a study done on former The Biggest Loser contestants, the lower metabolism brought on by the extreme weight loss lasted for years after the initial weight loss, even for those who continued to exercise. This leads scientists to wonder if diets lower metabolism permanently. In other studies, people who dieted to lose weight put themselves at higher risks for heart disease, diabetes and stroke than if they hadn’t dieted at all. What’s more, the phenomenon is magnified if people who are at a normal weight diet to lose weight. It’s estimated that 50% of women in the normal weight range diet each year. Which means these women are actually increasing the likelihood they will become overweight in the future.
While a proven way to lower a person’s SPW has yet to be discovered, events other than dieting can also increase a person’s SPW. Because SPW is closely linked to hormones, any event that dramatically affects hormones can increase one’s SPW. Think about how hard it is for some women to return to pre-pregnancy weight. And, women who may have kept the same weight since their twenties sometimes can’t maintain that weight into menopause.
Is There Any Good News?
Yes! Studies that appear to prove the existence of SPW also support other studies that show a person’s body weight and BMI are terrible indicators of health and mortality. Fitness – healthy eating and being active – is a much better indicator of health and mortality, regardless of a person’s weight. Meaning, if Susie, at 150 lbs, comprised her 1800 calorie diet of mostly healthy foods and exercised regularly to remain 150 lbs instead of dieting, she would have a greater chance of staving off lifestyle diseases that could be detrimental to her quality of life or shorten her lifespan, regardless of whether or not she lost a single pound.
What really needs to change isn’t our weights but our society’s attitudes about body weight. Think about the 50% of American women who are of normal weight who diet to lose weight every year. There’s no explanation for it other than they perceive their bodies don’t meet the standard – whatever that arbitrary standard may be. When we make the standard health and well-being, we need not, and should not, diet ever again.
Click here to link to a NY Times column by a neuroscientist who studies SPW theory and has experienced it personally.