For many people with type 2 diabetes, drugs like Ozempic have been a game-changer. These medications, known as GLP-1 receptor agonists, not only help stabilize blood glucose but often lead to meaningful weight loss, lowering the risk of diabetes complications.

Not everyone benefits equally from the drugs, however, and new research from Japan may explain why.

When a team of scientists tracked 92 people with diabetes during their first year on GLP-1 drugs, they discovered that the reasons people overeat may play a crucial role in whether the drugs deliver long-term success.

Put simply: if you eat because the sight or smell of food is irresistible, you're more likely to see positive results. But if you eat to soothe your emotions, the benefits may be harder to achieve.

People who reported high levels of external eating — being tempted by tasty-looking food — tended to experience the greatest weight loss and blood glucose improvements. Meanwhile, emotional eaters saw fewer benefits overall.

“Pre-treatment assessment of eating behavior patterns may help predict who will benefit most from GLP-1 receptor agonist therapy,” senior author Daisuke Yabe, a professor of Diabetes, Endocrinology and Nutrition at Kyoto University Graduate School of Medicine, explained in a media release.

“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.”

GLP-1 receptor agonists, including Ozempic, work in several ways. They lower blood glucose by boosting insulin secretion and help reduce weight by curbing appetite. Many patients see significant changes in cholesterol, body fat and glucose control. But the Japanese research team wanted to dig deeper into why not everyone experiences these benefits, so they focused on the psychology of eating.

Participants in the study answered detailed questions about their relationship with food. The researchers were especially interested in three eating patterns often leaked to weight gain:

  • Emotional eating: Turning to food in response to stress, sadness or negative emotions
  • External eating: Eating because the food looks or smells appealing, regardless of hunger
  • Restrained eating: Deliberately restricting food intake to lose weight.

It's worth noting that while restrained eating can be helpful in moderation, if taken too far it may trigger disordered patterns.

The researchers followed participants over a full year, collecting data at three different points: 1) the start of the treatment; 2) three months later; 3) and after 12 months. They measured body weight, fat percentage, cholesterol, blood glucose and skeletal muscle mass, while also recording eating behavior.

Overall, patients did lose weight and body fat, with cholesterol dropping as well. Interestingly, muscle mass stayed stable, which is an important benefit for people with diabetes. Blood glucose also improved, though not to a statistically significant degree.

But the most telling differences came from the way participants approached food. By three months, emotional and external eating had declined, while restrained eating increased. Yet, by the 12-month mark, emotional eating and restrained eating had crept back to their original levels. Only rates of external eating stayed lower, suggesting a lasting shift.

This mattered. People who reported high levels of external eating — being tempted by tasty-looking food — at the start tended to experience the greatest weight loss and blood glucose improvements. Meanwhile, emotional eaters saw fewer benefits overall.

If you eat because the sight or smell of food is irresistible, you're more likely to see positive results. But if you eat to soothe your emotions, the benefits may be harder to achieve.

“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,” Takehiro Kato of Gifu University, Japan, the second author of the study, said. “Individuals with prominent emotional eating tendencies may require additional behavioral or psychological support.”

Although impressive, the study has limitations. For one, it relied on self-reported data and people especially motivated to improve their diabetes management may have been overrepresented among the participants. Still, it offers a valuable clue as to why GLP-1 drugs don't work equally well for everyone.

“While our study suggests a potential association between external eating behavior and treatment responses to GLP-1 receptor agonists,” Yabe cautions, “these findings remain preliminary. 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.”

For patients and their doctors, the message may be that medications like Ozempic are powerful, but not a one-size-fits-all solution. Understanding why we eat — not just what we eat — could be the missing piece in making diabetes treatments work their best.

The study is published in Frontiers in Clinical Diabetes and Healthcare.