Is a new diet or exercise program working for a friend? If so, there's a good chance that you will try it, too.

A person who finds success in a wellness program is more influential in getting friends to sign up than a charismatic, but less successful pal, according to a study by University at Buffalo occupational health researcher Lora Cavuoto.

The study, "Modeling the Spread of an Obesity Intervention through a Social Network," was published in the Journal of Healthcare Engineering.

"People want to see that positive influence," says Cavuoto, assistant professor in the Department of Industrial and Systems Engineering, School of Engineering and Applied Sciences. "Understanding how social influence affects people's participation in health programs can lead to better-designed wellness interventions."

Engineering doctoral candidate Mohammadreza Samadi and engineering graduate student Mahboobeh Sangachin worked with Cavuto on the study.

Countless diets and weight-loss programs exist to combat the high rate of obesity among Americans. But they do little good if people don't adopt them.

Cavuoto's research will help diet and exercise programs reach more people by advising marketers on which people to target as endorsers.

The study simulated the behavior of fictional people created using combinations of physical attributes and personality traits, such as the ability to lose weight and a high or low body mass index. The model distributed traits based on national population averages.

Based on the simulations, people in social networks linked to someone who successfully lost weight or had a high body mass index produced the largest total weight loss among peers. The networks surrounding a person with a high number of friends -- those who were more charismatic or popular -- produced lower weight-loss totals.

Cavuoto's results support the new approach many weight-loss programs have taken in attracting new participants: Celebrity endorsers with a large reach have taken a backseat to everyday people who benefit from a new diet or workout.

"Your ties and social contacts may have a bigger effect because you see them every day and you have that close connection," says Cavuoto. "If they can be successful, then that's your best way of getting information out that a program is good."