Body Weight Set-Point Prevents Weight Loss
Losing weight is possible over the short term, but weight regain is the rule over the long term. The statistics tell us that people can generally lose about 10% of their weight with a concerted effort. The bad news is that almost everybody will quickly regain all their lost weight and often more.
Why is this? Eating more and exercising less can cause progressive weight gain, so why doesn’t eating less and exercising more cause progressive weight loss? To understand the reasons for this we first need to discuss some biology.
Human Biology Defends Body Weight Set-Point
The first point to understand is that the body is actively involved in weight regulation. The body has a weight “set-point” that it works hard to maintain. Much like a thermostat, if body weight drops below the set-point, changes are triggered that tend to bring body weight back into the desired range (reference).
The body controls weight by manipulating metabolic rate and appetite. There are a large number of hormones, peptides, nutrients, and neurologic mechanisms that are involved in weight regulation. What controls all these things and how they interact is not well understood. The complexity of it all suggests that weight regulation is an important and fundamental biologic body function.
This complicated control system increases appetite and slows metabolism when weight falls below the set-point. A slower metabolism conserves calories to limit weight loss, and an increased appetite causes increased calorie intake. These are powerful biologic mechanisms that do an extremely good job at keeping bodyweight within the desired range over time (reference).
People generally can overcome this and lose weight for a short time with diet and exercise, but ultimately an increased appetite and a slower metabolism make maintenance of weight loss virtually impossible.
The Body Weight Set-Point Can Reset Higher
The body is not nearly as good at preventing weight gain as it is at preventing weight loss. Unfortunately, as weight is gained, the set-point tends to ratchet up along with weight.
Not everybody, of course, is equally susceptible to weight gain. Some people have a very effective regulatory mechanism (increased metabolic rate, decreased appetite) that prevents body weight from rising above the set point, and some people don’t. This susceptibility to weight gain seems to be largely determined by genetics.
The Disease of Obesity
The disease of obesity occurs when the set-point becomes too high. The reason diet and exercise fail over the long term as treatments for obesity is because diet and exercise do not decrease the set-point.
A 2011 study by Sumithran and others published in the New England Journal of Medicine entitled Long-Term Persistence of Hormonal Adaptations to Weight Loss demonstrates how human biology vigorously opposes weight loss by increasing appetite.
The study showed that the levels of numerous hormones involved in the mediation of appetite significantly change after diet-induced weight loss to increase appetite and promote weight regain. Even one year after weight loss (and after weight regain had begun) significant changes in the levels of these hormones persisted. This suggests that the body will continue to fight weight loss long-term until weight regain back to the set-point occurs.
Kevin Hall, PhD., in a keynote speech at the 2017 ASMBS (American Society for Metabolic and Bariatric Surgery) Clinical Congress meeting (watch keynote speech), quantified the appetite increase that occurs with weight loss. He found that for every 1 kg of weight a person loses, appetite increases by 100 Calories/day. As more weight is lost, there is a continued increase in hunger, creating a stronger and stronger “pull” back towards the set-point weight.
A 2016 study by Hall and others published in the journal Obesity entitled Persistent Metabolic Adaptation 6 Years After “The Biggest Loser” Competition demonstrates how human biology vigorously opposes weight loss by decreasing metabolism.
This study evaluated resting metabolic rate in the contestants from Season 8 of the Biggest Loser show after initial weight loss, and again after 6 years. After initial weight loss, which averaged 58kg, resting metabolic rate decreased by an average of 610 Calories/day. At 6 years after the initial weight loss, despite an average weight regain of greater than 2/3 of the initial weight loss, resting metabolic rate remained, on average, 704 Calories/day less than before weight loss. This lowered metabolic rate also creates a “pull” back towards the initial set-point weight.
The fact that resting metabolic rate remained abnormally low after 6 years and despite significant weight regain suggests that the body continues to fight weight loss, even after many years, until weight regain occurs all the way back up to the initial set-point weight.
For an obesity treatment to be successful long-term it must lower the body weight set-point so the body doesn’t continually try to achieve weight regain. Diet and exercise don’t do this, and currently available medications don’t do this.
Weight Loss Surgery Lowers Body Weight Set-Point
Recent research suggests that weight loss surgery does change the body weight set-point. This is believed to be the reason why weight loss surgery works so much better than other weight loss methods for long-term weight loss. Read more about this exciting topic here.
Read more about Dr. Oliak and his Orange County weight loss surgery program at www.OliakCenter.com.