An expert workshop report on why preventing regain is the hardest part of weight loss: after losing weight, both appetite and metabolism adapt to pull you back. Here's what the science says.
View or Download the PDF
Physiology of the Weight-Reduced State - NIDDK Workshop, Obesity 2021 (PDF)
Preventing regain is the single hardest challenge in treating obesity. This report - from a National Institutes of Health workshop of leading researchers - lays out why: after losing weight, the body enters a "weight-reduced state" where both hunger and metabolism shift to defend against staying smaller.
Dr. Hammer's 5 Second Takeaways
Losing weight is easier than keeping it off
Most people can lose a meaningful amount of weight; far fewer keep it off. About half maintain a 5%-or-more loss at one year, and only about a third at two years.
The body defends a "set point"
Researchers describe a homeostatic weight - largely genetic but shaped by environment - that the body works to defend, pushing back when you drop below it.
Two forces work against you: appetite and metabolism
Appetitive adaptation increases hunger, and metabolic adaptation makes your body burn energy more efficiently (fewer calories). Both oppose maintaining a lower weight.
Maintaining weight loss may be its own distinct state
The biology of losing weight and of staying reduced may differ - which means the strategies, and treatments, that work best can differ too.
This points to better long-term tools
Understanding these mechanisms is how researchers are finding new targets to make maintenance more achievable. It isn't about trying harder.
Nerd-Out
The NIDDK workshop (June 2019; chaired by Rudolph Leibel and Kevin Hall) examined the physiologic and metabolic changes of the weight-reduced state: altered regulation of energy intake and expenditure, adaptive thermogenesis, and appetitive adaptation, framed around a genetically influenced "settling point." It surveyed the mechanisms that defend body weight, gaps in current knowledge, and emerging approaches - metabolomics, proteomics, new genetics strategies, and neuroimaging - to identify therapeutic targets for improving weight-loss maintenance. Whether the mechanisms opposing weight loss differ from those opposing weight gain, and whether weight loss and reduced-weight maintenance are distinct physiologic states, were central open questions.
Go to the Source:
This summary is drawn from "Physiology of the Weight-Reduced State: A Report from a National Institute of Diabetes and Digestive and Kidney Diseases Workshop" by Laughlin and colleagues (Obesity, 2021; 29:S5-S8). The full report is in the linked PDF above.