Mouse study: watching others eat may influence overeating

Watching others eat tasty foods may lead to overeating, even in the absence of hunger, according to a new mouse study being presented Monday at ENDO 2025, the Endocrine Society’s annual meeting in San Francisco, Calif. 

“This animal model opens the door to developing new treatments that target the brain’s reward system to help prevent or reduce overeating,” said Yong Xu, Ph.D., M.D., professor and associate director for Basic Sciences at the Children's Nutrition Research Center (CNRC), Baylor College of Medicine in Houston, Texas. “It also supports public health efforts that aim to limit the influence of visual food cues in media and social settings, which could help people better manage their weight and eating habits.”

The study was conducted by Xu Xu, M.D., pediatric endocrine fellow at Texas Children’s Hospital, and Hesong Liu, Ph.D., previous postdoctoral fellow at CNRC and currently assistant professor of Neuroscience and Physiology at Upstate Medical University in Syracuse, in Yong Xu’s lab. 

In the study, 14 mice were divided into two groups: group A mice were either fed or fasted overnight before testing, while group B mice were always fed before testing. The mice were paired based on genetic and parental information and placed in separate but nearby areas to observe each other without physical contact. The researchers measured the amount of food the mice ate hourly for four hours across different test days, using chow, high-fat, and sucrose diets. 

In a follow-up experiment, group B mice received injections of either 0.1 ml of 9% saline, a D1 dopamine receptor (DRD1) inhibitor (SCH23390, 0.1 mg/kg), or a D2 dopamine receptor (DRD2) inhibitor (Eticlopride, 1 mg/kg) 15 minutes before testing, and food intake was measured.

Interestingly, satiated mice that watched fasted peers eat did not consume more chow or high-fat food. However, they significantly increased their intake of the sucrose diet during the first hour of observation—both in the initial and repeated experiments. This overeating persisted after saline injections but was suppressed by dopamine receptor inhibitors.

“This study shows, in animals, that simply watching another eat—especially palatable food—can cause overeating, even when not hungry,” Xu said. “It also identifies a specific brain system (dopamine signaling) that helps explain why this happens. This type of behavior, driven by environmental and social cues, is very relevant in today’s world, where food is abundant and eating shows or food-related social media are common.”

The researchers suggest that recognizing this pattern may help people become more mindful of overeating, a major factor in obesity, and open the door for new treatments.

About Endocrine Society
Endocrinologists are at the core of solving the most pressing health problems of our time, from diabetes and obesity to infertility, bone health, and hormone-related cancers. The Endocrine Society is the world’s oldest and largest organization of scientists devoted to hormone research and physicians who care for people with hormone-related conditions.

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