It's one of nature's many cruel jokes. Even when an obese person loses a serious amount of weight through exercise and dietary changes, their overall hunger levels go up. And stay up.
According to a study out of Norway, published in the Jan. 23, 2018 issue of the American Journal of Physiology-Endocrinology and Metabolism, participants in a two-year weight-loss program were far hungrier at the end when they were thinner. Worse, their appetites showed no signs of returning to normal. The increased hunger might explain why only two out of 10 participants were able to keep their weight down after the study ended.
More than a third (36.5 percent) of all adults in the U.S. are obese, defined as having a body mass index of 30 or more. Obesity is a problem in all developed nations, even places like Norway, which has an adult obesity rate of 25 percent. Obesity has been linked to higher risks of heart disease, stroke, Type 2 diabetes and some cancers.
In the Norway study, 35 men and women with an average weight of 275 pounds (125 kilograms) participated in a rigorous weight-loss program that included three-week stints at a special facility every six months for two years. By the end, they had lost an average of 24 pounds (11 kilograms) each.
But at each step along the way, researchers quizzed them about their hunger levels. Not only did their subjective hunger levels increase and stay high throughout the two-year trial, but their blood showed higher levels of ghrelin, the so-called "hunger hormone."
"Everyone has this hormone, but if you've been overweight and then lose weight, the hormone level increases," says Catia Martins, an associate professor in the Norwegian University of Science and Technology's Department of Clinical and Molecular Medicine, in a statement.
Your stomach releases ghrelin to let your brain know that it's time to eat. Obesity experts believe that the level remains high because your body gets used to being overweight and panics a little when that weight goes down. So, it is trying to get the weight back, just to be "safe," evolutionarily speaking.
Because of this, Martins thinks obesity should be treated like any other chronic condition, such as diabetes.
"Obesity is a daily struggle for the rest of one's life. We have to stop treating it as a short-term illness by giving patients some support and help, and then just letting them fend for themselves," she says.