Why is the “freshmen 15” phenomenon so common?

Do not schedule eight AM classes. Communicate with your roommate. Wash your bedding regularly. Incoming college students are offered numerous pieces of advice before stepping onto campus. Arguably, one of the most common is to beware of the “freshman 15.” But why is weight gain among first-year students so universal that it has earned such a notorious reputation? 

An interdisciplinary research team led by Y. Alicia Hong, who studies mobile and wearable technologies and professor in the Department of Health Administration and Policy, found that the college environment lends itself to habits that increase food intake and subsequent weight gain. 

“Social and environmental factors are key determinants of eating behavior. College students are affected by the eating environment, especially where they eat and whom they eat with. Our research found that they consume more calories when eating in groups or formal dining settings,” said Alicia Hong. 

Over the course of four weeks, college students self-recorded daily eating behaviors, environment, and mood and stress levels using a mobile app. App-logged responses indicated participants eat more when in groups of two or more and in locations such as dining halls or restaurants. Conversely, food intake was less when alone or at home.  

College students are unaware of their eating habits, findings suggest. Analysis revealed that students’ perceptions of their food consumption did not align with the caloric intake logged. Factors related to gender and emotion also contributed to the complex nature of dietary behavior.  

“College students’ eating behaviors are complex, with individual, interpersonal, and environmental factors interacting to influence dietary intake. This research underscores the importance of context in dietary intervention and incorporating digital tools for dietary assessment,” said Hong. 

The research team included Distinguished University Professor in the Department of Nutrition and Food Studies Larry Cheskin, Associate Professor in the Department of Health Administration and Policy Hong Xue, and MS Health Informatics graduate Jo-Vivian Yu. 

The Dynamics of Eating Behaviors and Eating Environment in College Students: Discrepancies Between App-Tracked Dietary Intake and Self-Perceived Food Consumption was published in mHealth on October 29, 2025.