GLP-1 agonists—so-called “wonder drugs” like Ozempic or Wegovy that help individuals lower blood sugar levels and lose weight, among other things—yield significant results for some patients, but not all. People’s motivations to overeat may play a role in this, according to a new study.

To investigate why some people don’t benefit from GLP-1 agonists as much as others, researchers observed 92 participants with type 2 diabetes in Japan during their first year of taking GLP-1 drugs. Their results, published today in Frontiers in Clinical Diabetes and Healthcare, suggest that people who overeat due to external reasons—such as the sight or smell of delicious food—had greater chances of responding well to the drugs in the long term than people who overeat for emotional reasons.

Who will benefit most from GLP-1 drugs?

“Pre-treatment assessment of eating behavior patterns may help predict who will benefit most from GLP-1 receptor agonist therapy,” Daisuke Yabe, senior author of the study and a professor of diabetes, endocrinology, and nutrition at Kyoto University, said in a Frontiers statement. “GLP-1 receptor agonists are effective for individuals who experience weight gain or elevated blood glucose levels due to overeating triggered by external stimuli. However, their effectiveness is less expected in cases where emotional eating is the primary cause.”

The team revealed this by gathering data on the participants’ body weight and composition, diet, and information such as blood glucose, cholesterol levels, and relationship with food at the beginning of the treatment, three months after, and one year after. They focused on emotional eating (eating in response to negative emotions), external eating (eating because the food looks good), and restrained eating (controlling one’s diet to lose weight). While it might seem contradictory, excessive restrained eating can actually result in disordered eating, according to the researchers.

Over the year, the participants experienced a statistically significant loss of body weight and lowered cholesterol levels and body fat percentage without changing skeletal muscle mass. While blood glucose levels ameliorated, the improvement wasn’t statistically significant. There were, however, some variations depending on eating behaviors. Three months after the start of the treatment, participants reported more restrained eating and less external or emotional eating. By the end of the year, though, participants had returned to their original restrained and emotional eating habits.

“One possible explanation is that emotional eating is more strongly influenced by psychological factors which may not be directly addressed by GLP-1 receptor agonist therapy,” said Takehiro Kato, second author of the article and a researcher from Gifu University, “Individuals with prominent emotional eating tendencies may require additional behavioral or psychological support.”

External eating lessened over the year of treatment

Participants reported decreased external eating throughout the entire year, and individuals that claimed high levels of external eating at the beginning of the treatment saw the greatest benefits in blood glucose levels and weight loss. On the other hand, the team didn’t identify any association between emotional or restrained eating scores at the beginning and drug benefits by the 12-month mark.

“While our study suggests a potential association between external eating behavior and treatment response to GLP-1 receptor agonists, these findings remain preliminary,” explained Yabe. What’s more, the team’s study was observational, and participants self-reported information, meaning the researchers revealed a potential association, not a causation.

“Further evidence is necessary before they can be implemented in clinical practice. Should future large-scale or randomized controlled trials validate this relationship, incorporating simple behavioral assessments could become a valuable component in optimizing treatment strategies,” Yabe concluded.