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Miscounting calories: To see what you've burned, don't necessarily trust your treadmill

IT MAY look all innocent sitting down there in your basement, but your treadmill may be deceiving you. The fact is, you can't always believe the "calories burned" totals that appear on workout equipment.

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IT MAY look all innocent sitting down there in your basement, but your treadmill may be deceiving you. The fact is, you can't always believe the "calories burned" totals that appear on workout equipment.

Each manufacturer uses its own algorithm to calculate duration and intensity, so calorie estimates are just that. Depending on the equipment and the manufacturer, the numbers can be off by 20 to 30 percent, according to some reports.

Besides that, the number of calories you burn during your workout depends on variables like your sex, age, weight, body-fat percentage and metabolic rate. Even the medications you take can affect the figures.

Naturally, a heavier person burns more calories. People with lots of muscle mass burn more, too. And if you white-knuckle the hand rails, you can falsely boost the numbers for calorie expenditure.

Let's not forget that machines are typically calibrated for a man weighing between 160 and 180 pounds. If you weigh less or more than that, your caloric expenditures will be off.

The better way to go, if you're OK at math, is to consult a good, old-fashioned energy-expenditure chart.

What you'll find, for example, is that a person who walks at an easy pace (3 mph) will burn .06 kilocalories per kilogram of body weight per minute.

That's about 3.5 calories per minute for someone who weighs 130 pounds (59 kilograms), 4.08 calories per minute for someone who weighs 150 pounds (68 kilograms) and 5.5 calories per minute for someone who weighs 200 pounds (91 kilograms).

So the 130-pound person walking on a treadmill at that pace would burn approximately 210 calories in an hour, the 150-pound person 245 calories an hour and the 200-pound person 330 calories an hour.

(If math's not your thing, the website whyiexercise.com has calorie expenditures for lots of activities at a range of weights in its "metabolic equivalent" area.)

Using the calories-per-minute numbers above as a guide, you can find out pretty quickly whether your treadmill at home or at the gym is calibrated appropriately for you. Hop on, set the speed to 3 mph, walk for 15 minutes and see if the result is in the right ballpark.

(Remember, though, that walking on the treadmill is easier than walking outdoors where you'd have to deal with wind resistance and hilly terrain, and have nothing giving you a push forward.)

The more briskly you walk, the more calories you'll burn. But as I've said before, if you want to burn fat, you also need to eat sensibly - end of story, period. No amount of exercise can overcome gluttony.

Ultimately your goal is to get into better cardiovascular shape, and to feel and look better.