Forget just feeling the burn. Some people tired of the treadmill and frustrated with food diaries are turning to pricey gadgets that can help them see the burn.

Companies – including Nike, Polar Electro and Timex, which already offer gadgets like pedometers and heart monitors to help people fine-tune their workouts – have started adding calorie counters and special Web sites.

Experts say the calorie-counting gadgets are far from 100 percent accurate but better than the guesswork most people use.

“It seems simple: If you expend enough calories, as many as you consume, you won’t gain weight,” said Janet Rankin of the Institute for Biomedical and Public Health Sciences at Virginia Tech. “But it’s not easy for the average person to know how many calories I’m using in that workout, that aerobic dance class I just did.

“In general people are going to overestimate. … I think these kind of tools can provide a little bit of a reality check and serve as a marker for improvement.”

The arm bands, chest straps and wrist bands try to offer a glimpse of information that typically can be seen only in a lab. The calorie counters are based on two methods researchers use: how much oxygen is being used and how much heat is being produced.

Most of the calorie counters on the market use a chest strap to measure heart rate. While exercising, the harder the heart works, the more oxygen is used and the more calories burned.

Robert Dojonovic, of Monessen, Pa., works out at the Center for Fitness and Health in Rostraver, Pa. Dojonovic wears the calorie-counting Bodybugg by Pittsburgh-based BodyMedia. The device, which costs between 00 and 00, uses sensors that measure skin temperature.

Timex has nine digital heart monitors with calorie monitors, ranging in price from the 5C351 Digital Heart Rate Monitor for $70 to the Ironman Triathlon, for $90. Most of Polar Electro’s heart monitors also calculate calorie burn; Polar’s newest F-series models range from $89.99 to $159.99.

Nike has at least three heart rate monitors that try to count calories, including the $99 Imara HRM and SDM Tailwind and the $109 Triax C-6.

Bodybugg, the latest gadget, uses a different method. It has sensors that measure skin temperature, its electrical conductivity and how much heat someone’s body is producing and losing, because energy used by the human body eventually is turned into heat. The device doesn’t have a heart monitor, but the manufacturer, BodyMedia, is working on a way to measure heart rate through the upper arm.

The Bodybugg is more expensive – $300 to $500 – and only available through gyms with agreements with Camarillo, Calif.-based Apex Fitness Group. Apex recently unveiled the arm band at more than 1,000 gyms nationwide, including Gold’s Gym and World Gym, and plans to sell the Bodybugg outside gyms soon.

People using the Nike, Polar and Timex models can keep tabs on their calorie burn by pushing a button and glancing at their wrists, while the Bodybugg has no display – meaning users have to go online. The gadget’s maker, Pittsburgh-based BodyMedia, says a display may be added in later models.