It is often said that losing a lot of weight is nowhere near as difficult as keeping weight off over time, and now we know why. A recent Norwegian study found that obese people who lose weight feel significantly hungrier than they did before and no diet plan on Earth may be able to make the hunger subside.

Step One: Shedding Weight From Obesity

Researchers led by Catia Martins, an associate professor at the Norwegian University of Science and Technology, enlisted 34 participants who weighed an average of 275 pounds and were categorized as suffering from “severe” obesity.

Over the course of two years, participants underwent a weight loss program that involved a rigorous diet and exercise routine that Martins called “the gold standard in obesity treatment.” Each participant lost an average of 24 pounds throughout the program and was able to keep their weight off. But as their health improved, the participants reported feeling increasingly hungrier.

Why They Got Hungrier

Feelings of hunger were reported on a scale of 0 to 100, with 100 being the hungriest the participants had ever felt. When the study began, the average participant reported a hunger level of 53 before a meal. After two years had passed, that number had increased to 73.

This wasn’t a surprise considering the researchers’ discovery that during the study, participants had higher levels of ghrelin, a hormone associated with hunger. So, when someone loses weight, the body produces more ghrelin, making that person feel hungrier as he or she loses more weight.

“Everyone has this hormone, but if you’ve been overweight and then lose weight, the hormone level increases,” Martins said.

You might think that ghrelin levels would have balanced out by the end of the study but this was not the case, which suggests that the participants’ feelings of hunger will remain high or increase even higher for the rest of their lives.

Tricked Into Eating By Your Own Body

This sheds light on why it’s so difficult for obese people to keep weight off: The more weight they lose, the hungrier they get.

Making the increased hunger even more perplexing is the fact that people who lose weight require less energy and therefore need to eat less than they used to. But the study shows that even though someone doesn’t need extra energy from food, the body induces feelings of hunger as if it was indeed craving energy.

One possible explanation for this is that the body is trying to conserve energy following the weight loss under the assumption that it will need the energy to support the body once it returns to its previous form (obesity).

“This means that patients with severe obesity who have lost significant amounts of weight with lifestyle interventions, combining diet and exercise, will have to deal with increased hunger in the long-term,” the researchers wrote.

Is Obesity A Lifelong Disease?

The team also believes that their results have proven that obesity should hereby be known as a chronic or lifelong disease.

"Obesity is a daily struggle for the rest of one's life," Martins said. “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.”

It seems that only with the help of regular doctors’ appointments for several years at least can a formerly obese person remain healthy.