the New York Times / STUART BRADFORD

The newest weight-loss coach is a mouse-click away, with scores of Web sites and online newsgroups offering guidance and support to dieters and exercisers.

Some sites are free, offering calorie-counting, nutritional and activity databases to help users get and keep a grip on just how long they’ll need to exercise to burn off the calories they’re logging every day.

Other sites charge an annual or weekly fee for similar services, along with access to how-to fitness videos and other coaching tools.

Some — such as Apex Fitness’ popular Bodybugg monitors, heavily marketed through the 24-Hour Fitness club chain — track a user’s activities from showering and shopping to a spinning class.

Then there are gaming programs such as Nintendo’s Wii Fit, and My Weight Loss Coach. The Wii Fit is a particularly kid-friendly set of hardware — a pressure-sensitive pad that communicates wirelessly with the Wii console — and software activities based on aerobics, strength training and yoga.

Do the high-tech programs work better than old school diet-and-exercise regimens? Medical studies suggest that they can — if the participants stick to the program and make behavioral changes in their lives.

A 2006 study of Internet weight-loss programs, published in the scientific journal Nature, compared participants in eDiets, a commercial online weight-loss program, with participants in VTrim, a weight-loss program delivered online and led by a therapist.

Both groups lost weight, but the VTrim subjects lost significantly more weight and kept the weight off. The VTrim group’s advantage? Following a structured curriculum — online lessons and activities to modify eating behavior and exercise habits.

“Still, widespread online weight loss is promising from a public-health standpoint,” the authors wrote, praising the 24-hour support offered by online weight-loss programs. Chat rooms, discussion boards and e-mail support can help motivate faltering dieters and bring them back on track.

How to sift through thousands of online weight-loss sites to find the program that will work for you?

Look for these basics:

•Questions that determine your height, weight, age and weight loss or fitness goals (and, ideally, your body-fat ratio).

•A food journal to monitor daily calorie intake.

•An activity log with a drop-down menu of tasks and exercises.

•An educational element (behavior-modification articles, e-mail access to a therapist or personal trainer).

•Community support via e-mail, chat rooms or discussion boards.

Then stick with the program. Merely keeping an honest daily food journal can double weight loss, according to a Kaiser Permanente study published last year in the American Journal of Preventive Medicine.

Pedometers and monitors serve as motivators and nags. Bodybugg users know that their monitors interface with their computers and can distinguish whether a wearer spends 15 minutes on the treadmill or on the couch in front of the TV.

The bottom line, as fauljosh, a user at My Weight Loss Coach, noted in a discussion group, requires commitment.

“I bought this a few weeks ago hoping to use it to supplement my Wii Fit workout,” fauljosh wrote.

“The software is decent but I ended up not really using it much. Only because you have to really stick to it. You’re expected to use it every day.”Look for specific, concrete help

Be alert when you search online for high-tech workouts: Look for specific, concrete help. To be useful, a site should require information about your height, weight, age and activity level to tailor an accurate activity log and daily calorie requirements.

For example, caloriecounter.com, a marketing-oriented site that offers hyperlinks to commercial weight-loss sites, is very different from the similar-sounding caloriecount.about.com.

The former aims to sell products and services. The latter is a free-registration site affiliated with about.com. It offers virtual community support, logs to record food intake, activity and weight, and impressive food and recipe databases.

Here’s a handful of other weight-loss sites geared to motivate people into making the lifestyle changes required to lose weight and get fit:

•traineo.com Free. Calorie and activity log, plus Motivators — support from invited friends or relatives who keep users accountable, diet tracking and a forum for posting success stories, advice and questions.

•hungry-girl.com Free. Useful and witty, with such links as Chew The Right Thing (seasonal recipes and advice) and Girls Bite Out (product and menu picks and pans).

•hyperstrike.com $90 a year includes an online fitness assessment, more than 600 detailed video exercises and a workout calendar to log progress.

•sparkpeople.com Free. Great for the gregarious, with tons of e-mail and support from other members, merit-point rewards and excellent articles.

•thedailyplate.com and livestrong.com Free. Require registering through livestrong.com, the foundation associated with cyclist Lance Armstrong. Thedailyplate is user-friendly, and basic — data in, data out — with a menu of activities even longer than the popular Bodybugg.

— CLAIRE MARTIN