Tackling a weight problem is often viewed as a personal responsibility that requires making healthier choices. The latest research, however, shows that external factors—from family and friendships to advertising and the workplace environment—make an equal, if not greater, contribution. Just look at the stats: A person's chance of becoming obese increases by 57 percent if a close friend is obese, 40 percent if a sibling is obese, and 37 percent if a spouse is obese.

That's where Thinfluence comes in. Through a research-based examination of various social, environmental, and policy-based issues, renowned Harvard researchers Dr. Walter Willett and Dr. Malissa Wood examine how relationships, workplace, media, and other factors are affecting readers' weights. Thinfluence doesn't tell readers to ditch their friends and family, change jobs, or move to another state. It offers a clear three-step action plan—analyze, act, influence—for readers to identify hidden factors affecting weight, develop a personal toolbox to combat external effects, and become positive influences on others around them.