About 67 percent of U.S. adults age 20 or older are overweight or obese, according to the National Center for Health Statistics. So many bulging waistlines means quite a market for creators of diet plans. How do you decide which diet plan to try? To help you evaluate the options, we've compiled information about six popular diet plans that have been studied sufficiently to assess their effectiveness, according to an analysis by Consumer Reports, which weighs in on the topic every few years. (The last CR update was issued in 2007, and the magazine plans to revisit diet plans in 2011.) One tip: Don't repeat a diet program that hasn't worked for you in the past. "Any diet that gets repeat customers is probably not effective," says James Hill, director of the Center for Human Nutrition at the University of Colorado–Denver.
Whichever diet plan you choose, be aware that you'll need to make a lifestyle change that continues after the program if maintaining weight loss is the goal. "You're not likely going to keep the weight off just by following any of these diets," Hill says. "You need a different long-term strategy that has to include physical activity."
Description: Based on the book Volumetrics: Feel Full on Fewer Calories by Barbara J. Rolls (HarperCollins, 1999), the Volumetrics diet encourages eating low-density foods—choices that are low in calories but high in volume—to help you feel full and satisfied while losing weight. Participants in this diet are taught which foods work best (or don't work at all) in a low-calorie diet, and the book provides a menu and exercise plan, too. Favored foods under the plan: beans, fruit, low-fat fish, lean meat, low-fat milk and other dairy items, skinless poultry, and whole grains. Foods to avoid: candy, cookies, and high-sugar drinks.
Studies show: Research shows this diet offered the best shot at weight loss of all the diets for which Consumer Reports most recently evaluated scientific evidence. It earned high marks for short-term and one-year weight loss, and the magazine gave Volumetrics its highest rating for "nutrition analysis"—a measure of how well the diet stacks up against the U.S. Dietary Guidelines for Americans.
Experts say: This diet "makes a good deal of sense scientifically," says Lawrence Cheskin, director of the Johns Hopkins Weight Management Center in Baltimore. "What actually stops our eating too much is that we feel that we're filled up." Salads, for example, are desirable, as are any foods that have high fiber and water content levels because they "make you feel fuller with less calories."
Description: This weight-management program, more than 40 years old and known for its weigh-ins and weekly meetings, is based on four "pillars": healthy weight loss (up to 2 pounds a week and possibly more after the first three weeks), a plan that fits into your life (by including the flexibility to eat any foods you like as long as the points assigned to each add up to no more than your daily target), the ability to make informed choices (by explaining why certain choices are important), and finally, a holistic view that incorporates behavior (by teaching you how to deal with hunger and handle temptation), exercise, food, and support.
Studies show: Participating in Weight Watchers produces average weight loss in the short term, according to Consumer Reports, and participants seem to be able to adhere to the plan over the long term. It also earned CR's highest mark for nutrition analysis.
Experts say: Weight Watchers is a "reasonable, sensible diet," Cheskin says. Hill agrees that the diet can result in health-improving weight loss but notes that you may grow weary of taking part in the Weight Watchers activities. "Even successful people get tired of going to groups," he says. (You can also sign on for the do-it-yourself version of the program online.)
[Learn why you shouldn't rely on marketing when considering Weight Watchers or Jenny Craig.]