Having an overweight roommate can make college women gain less weight according to a study released by Michigan University.

The normal weight gain by college students is between 2.5 lbs and 6 lbs and some gain up to 15 lbs, known as the “Freshman fifteen”, however according to researchers the difference was an average half-pound weight gain compared with an average 2.5-pound weight gain.

The study covered 144 female college students who were randomly assigned roommates at the start of freshman year.

"It's not really the weight of your roommate that's important, but the behaviors your roommate engages in," said study co-author Kandice Kapinos of the University of Michigan in a news release."These behaviors are what may really be 'contagious.' "

According to Kapinos, heavier freshman women are more likely to diet, exercise more, take dietary supplements and participate in college rationed meal plans thus creating a healthier environment for friends and roommates.

The main causes of the weight gain are increased alcohol intake and the consumption of fat and carbohydrate-rich cafeteria-style food and fast food in university dormitories. Other causes include stress, malnutrition and decreased levels of exercise.