In the spring of 2005, after four pregnancies, Julie Marsh weighed 240 pounds. “I wasnt happy with myself,” she told Health magazine in April 2007. Inspired by her sister Cathy Andrew, who had resolved to lose weight in 2005, the sisters joined forces in dieting and exercising and had better success.

Research shows that dieters are more likely to change their ways if they feel they have the support of family, a close friend, or a coworker. It worked for this sister team: Along with eating more vegetables and smaller portions, they lifted weights three times a week and went on four to five mile walks at least four days a week. The workout buddies even tried activities they wouldnt have done alone, like yoga and badminton. A year later, Julie had lost 85 pounds, and her sister had shed 105—a whopping 190 pounds of combined success.

Here are some tips for getting friends and family to support your desire to lose weight:

  • Be up-front. Let friends and family know you're making changes in your eating habits. It may stop loved ones from offering you foods you're trying to avoid and encourage healthy cooking at group events. Asking them for help also adds accountability.
  • Buddy up. The fact is, two-thirds of American adults are overweight and, chances are, you have friends or coworkers who may be interested in changing their eating behavior as well. Research shows that when one person slims down, those around him or her are more likely to lose, according to a 2007 study by researchers at Harvard Medical School and the University of California, San Diego.
  • Start small. If you're worried about food pushers, make small, less noticeable changes instead of obvious ones. It will help you ease into weight loss and avoid unwanted attention. For example, at the next family dinner, use a salad plate when you go through the buffet. Chances are, no one will notice your little switch, and you'll be consuming less food.