Keeping weight off is notoriously difficult, and a small new study sheds light on why it's so hard: To truly keep the pounds away, people may have to deal with feelings of increased hunger for the rest of their lives.
The study, from researchers in Norway, involved 34 patients with "severe" obesity who weighed 275 lbs. (125 kilograms), on average, at the study start. The individuals participated in a rigorous, two-year weight-loss program involving diet and exercise, during which they lost about 24 lbs. (11 kg) on average.
Participants were able to keep their weight off for this two-year period, but their levels of the hunger hormone ghrelin increased, and those increases lasted for the entire study. What's more, participants also experienced increases in their feelings of hunger, and these feelings never went away.
For example, at the start of the study, participants rated their hunger level before a meal at about 53 on a scale of 0 to 100 (where 100 is maximum hunger), on average. At the end of the two-year study, participants rated their hunger levels before a meal at 73 out of 100, on average.
The findings suggest that, "after lifestyle-induced [weight loss], patients with severe obesity will … have to deal with increased hunger in the long term," the researchers wrote in their study, which was published Jan. 23 in the American Journal of Physiology-Endocrinology and Metabolism.
On top of the increase in hunger, people's bodies become more efficient in using energy after weight loss, previous research has shown. That means that these individuals need to consume fewer calories than before to maintain the same weight.
For example, compare a person who has weighed 176 lbs. (80 kilograms) their whole adult life to a person who got to 176 lbs. after losing weight. The first individual can eat about 400 calories more a day than the second person and still maintain the same weight, said study co-author Catia Martins, an associate professor at the Norwegian University of Science and Technology.
The researchers said their findings show why obesity should be considered a chronic disease.
"Obesity is a daily struggle for the rest of one's life," Martins said in a statement. "We have to stop treating it as a short-term illness, [which we do now] by giving patients some support and help and then just letting them fend for themselves," Martins said.
Like other chronic diseases, obesity requires a lot of help and close follow-up from doctors over years to treat, Martins said.