Before you throw up your hands in exasperation (and toss a bag of chips into your grocery cart), read Prevention's report. We delved into the latest research-including new studies calling into question the long-term effectiveness of popular diets-and interviewed leading weight loss specialists, nutritionists, and, yes, real dieters to zero in on the diet foods that really can help you lose. What follows: the science behind the products, who they're best for, and what not to waste your money on.
Americans spent about $1.4 billion on low calorie frozen dinners (such as Lean Cuisine, Weight Watchers, and Healthy Choice) in 2004. These single-serving diet foods cost $3 to $5 each, pack up to 400 calories, and can be quickly microwaved for lunch or dinner.
The Science A 2004 University of Illinois study found that women who followed a 1, 365-calorie diet in which they ate two packaged frozen entrÃ©es a day shed about 5 pounds more in 8 weeks than those who were instructed to follow a diet (with the same number of calories) based on the food pyramid.
Use Them If you find it hard to guesstimate portions. "Frozen meals give your eyes and stomach a chance to readjust to what servings should be-I often advise patients to eat them for a week or two, and then keep the little trays and use them while making dinner as an easy way to eyeball portions, " says Madelyn Fernstrom, PhD, director of the Weight Management Center at the University of Pittsburgh Medical Center.
Low calorie frozen meals are also a sound option for busy dieters with no time (or desire) to cook and those who would otherwise grab fast food or order in pizza. "I've used them over the years whenever I've needed to lose weight because you can't beat the convenience: You just pop them into a microwave. And there's no way you can overeat, " says Michelle Tennant, 36, a publicist in Asheville, NC. "I try to pick the ones that have whole wheat or are mostly meat and vegetables, as I find they stick with me longer and I don't have a blood sugar crash."
Lose Them If you're a foodie. "If you savor your meals, enjoy cooking, and really notice the different tastes, textures, and smells of food, these products won't offer enough stimulation for you, " says Wahida Karmally, DrPH, RD, director of nutrition at the Irving Center for Clinical Research at Columbia University. The skimpy servings also may not provide enough calories if you're fairly active. "I used to take Lean Cuisine entrÃ©es to work and eat them for lunch because they're so convenient, but the portions were way too small to satisfy my appetite, " says Sylvia Sklar, 60, a professor at McGill University in Montreal.
"I was starving an hour later." One reason: Some of these dinners have less than 20 g of protein per serving-not enough to keep many women, especially active ones, satisfied, says Kathy McManus, RD, director of the department of nutrition at Brigham and Women's Hospital in Boston. If that describes you, look for a product with at least 20 g of protein, such as Kraft's line of South Beach Diet frozen entrÃ©es and Lean Cuisine's new Dinnertime Selects. One final caveat: Avoid this diet foods category if you have high blood pressure. Many entrÃ©es have 800 mg of sodium or more, about one-third of the federal government's recommended upper limit for a day's intake.
Bottom Line They can give dieters a push. "Frozen entrÃ©es may make dieting easier because they remove the guesswork when it comes to figuring out portion sizes, " explains Donald Hensrud, MD, an obesity specialist at the Mayo Clinic in Rochester, MN. Just make sure to supplement your low calorie meal with hefty sides of fruits and veggies to ensure you get enough nutrients and stay full. "The fruit and vegetable portion in most of these meals is tiny. You need 7 to 10 servings of fruits and vegetables a day, " says Karen Collins, RD, nutrition advisor to the American Institute for Cancer Research.