Friends, family can influence your weight—for good or bad

Efforts to lose weight and lead a healthy lifestyle can be influenced positively—or negatively—by people closest to you, including your friends, family, spouse, and co-workers, according to Walter Willett, Fredrick John Stare Professor of Epidemiology and Nutrition and chair of the Department of Nutrition at Harvard School of Public Health (HSPH).

Individuals can undermine others’ weight-loss plans by encouraging unhealthy eating habits or sedentary behavior, Willett said in an August 6, 2014 interview on WGBH’s Boston Public Radio about his new book Thinfluence. The book examines how friends, family, advertisements, entertainment, and other environmental factors influence body weight.

Research has shown that a person’s chance of becoming obese increases by 57% if a close friend is obese, 40% if a sibling is obese, and 37% if a spouse is obese, according to the Thinfluence authors. “Obesity is ‘contagious’ but physical activity and healthy eating are too, so we want to emphasize the latter,” Willett said. “Invite friends to join you for a walk or for an evening of cooking healthy foods. Bring your friends along in a positive way. That is the ultimate goal.”

Co-authors of the book are cardiologist Malissa Wood, assistant professor of clinical medicine at Harvard Medical School, and Dan Child of ABC News.

Listen to the Boston Public Radio interview

Read more about Thinfluence

Learn more

The Healthy Eating Plate (HSPH Nutrition Source)

The Benefits of Physical Activity (HSPH Nutrition Source)