Scientists may have found a new tool to help those struggling to lose weight for reasons beyond their control.

Researchers from the University of Copenhagen discovered that a certain group of obese people who struggle to lose and maintain weight loss respond well to liraglutide—a medicine that is a modified form of the appetite-inhibiting hormone GLP-1 that is naturally secreted from the intestine when humans eat.

An estimated 2 to 6 percent of all people with obesity develop the condition in early childhood, where mutations in the appetite genes give individuals a strong genetic predisposition for developing obesity with a condition called monogenic obesity.

This group of people do not often respond as well to existing treatment, and while diet and surgery can help, the long-term effect is often poor and the individual is unable to maintain weight loss.

“These people develop obesity because they are genetically programmed to do so,” associate professor Signe Sørensen Torekov from the Department of Biomedical Sciences and the Novo Nordisk Foundation Center for Basic Metabolic Research and lead author of the study, said in a statement. “That is, they are struggling with what is probably the strongest human drive: the desire to eat and thus to survive.

“However, the appetite-inhibiting drug liraglutide has a positive effect on them,” she added. “They feel less hungry and lose six percent of their body weight within four months.”

The researchers examined 14 people with obesity caused by pathogenic mutations in the MC4R gene and 28 people with obesity without the genetic mutations. They treated both groups with medicine for four months without no additional changes to diet or level of exercise.

After four months, the people with the most common form of monogenic obesity lost about 15 pounds, while the individuals with common obesity lost about  13 pounds

“We are positively surprised to see that the treatment has a good effect on this group of people,” Torekov said. “Many researchers have believed that the function of the medicine was mainly to inhibit the appetite by stimulating this specific appetite receptor in the brain which does not work in this particular group of people with obesity. However, our study shows that the medicine still has an appetite-inhibiting effect and thus must affect the appetite in a different way.”

While medicine that acts as an analogue to the natural GLP-1 hormone already exists, the new study shows that it can treat the most common form of genetically caused obesity.

“People who have suffered from obesity all their lives probably are not aware that it is caused by this mutation,” first-author of the study, PhD student Eva Winning Iepsen at the Department of Biomedical Sciences and the Novo Nordisk Foundation Center for Basic Metabolic Research, said in a statement. “It can therefore be a huge relief for many to learn why they have developed obesity and that there is actually a treatment that works.”

The study was published in Cell Metabolism.