Best Diet Websites

Who doesn't need a helping hand when it comes to losing weight? In fact, a Brown University study found that online weight-loss programs that were based not only on good medical information but also offered feedback from a professional were more successful for dieters than those that were only information-based. To find the best of the leading diet sites that offer solid advice and support, the Good Housekeeping Research Institute examined the 10 most popular, assessing the sites' questionnaires (to be sure they're analyzing your needs properly), experts' credentials, variety and value of diet recommendations including reasonable expectations for weight loss, Internet privacy policies, and ease of site navigation. We've also noted if these sites have a fitness component (if that's more what you're after, see our Top Fitness Sites). Keep in mind: Before starting a new diet, consult your physician.

Overall Best Diet Site

SouthBeachDiet.com ($65/13 weeks)

This science-based diet from cardiologist Dr. Arthur Agatston began when he was looking for a way for his overweight patients to make healthier food choices and lose weight to reduce heart strain and other vascular problems that result from obesity. The site is easy to navigate and has many tools, like a grocery-shopping planner, a guide to staying on the program when dining out, and a recipe archive. The program includes daily snacks and dessert, so you won't feel deprived. However, there are initial diet restrictions. In the first two weeks, the diet prescribes omitting grains, sugar, and fruits, which could be discouraging to some. The site also offers good expert feedback — something you won't get from just buying the book. While one-on-one counseling is available for $3 per week, you can post on the "Ask the Nutritionist" message board for a fast reply. The site also includes the South Beach Diet Fitness Club, consisting of Pilates-based core movements with pictures and step-by-step video instruction.

Best Active Community

Diet.com ($40/month, $140/year)

This site has an extensive introductory questionnaire that helps tailor meal plans and advice to your eating style and personality (heavy snacker, mindless eater, and more). Users also have easy access to the staff doctor, Dr. Robert Kushner, a professor at Northwestern University's medical school and president-elect of the Obesity Society. You can e-mail or post personalized questions to the "Coaching Corner" for same-day responses from Dr. Kushner. The site hosts live weekly chats with diet and fitness experts, message boards, and a buddy system to pair you with a fellow dieter for more motivation. Also offered is advice on coping with emotional concerns that often lead to overeating, although our expert couldn't find any articles on maintenance and avoiding weight regain. Fitness information — including workout planners and video exercises — is included.

Best Free Advice

SparkPeople.com (free)

Very customizable meal plans allow you to enter health concerns like "low-cholesterol" and "low-sodium," something that wasn't offered on other sites. The program is broken into stages one through four, to help move you through the journey of weight loss one step at a time. The online community is very active, and "Spark Teams" of other members will help keep you motivated on bad days. Somewhat unconventional meals (example: black beans and corn over rice, cottage cheese, and a cookie) might not be appealing or satisfying for everyone. Sparkpeople's fitness component is just as extensive as the nutrition section.

Next: Best for non-chefs, plus a flexible plan and a holistic plan