When it comes to weight loss, food and exercise aren’t the only things you need to be choosy about. Your friends and family can affect your ability to shed those unwanted pounds. Researchers already knew that bad habits traveled in packs. People with friends or family who smoked or drank alcohol—or were obese—tended to share those behaviors. This “halo effect” now seems to also have a positive influence on health. Obesity is a family disease. Children learn many of their exercise and dietary habits from their parents. Families can, however, support each to achieve better health. In one study, researchers looked at the family members of patients undergoing gastric bypass surgery to help them control their food intake. The patients—and often the family members—also attended support meetings to learn healthier food and exercise choices. A year after the surgery, many family members had also shed pounds, up to five percent of their initial body weight. This may not sound like much, but it’s enough to reduce their risk of obesity-related diseases such as diabetes and heart disease. Family members also showed increased activity levels, improved eating habits, and less alcohol consumption. This support mechanism also extends to friends and coworkers. In a separate study, researchers followed a weight loss competition in Rhode Island. Weight loss varied across the teams, but the people who lost the most weight tended to be on the same team. The largest weight loss was in line with the other study, around five percent. Teams were competing to lose the most weight so there was a “significant social influence” keeping them on track. Team captains lost more weight than the other team members, possibly because they were more motivated to win. Next time you run out for a double or triple cheeseburger, think about your friends and family. You could be the motivation they need to lead healthier lives.