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Exercise and Weight Loss

How Many Calories Are You Really Burning?


Updated June 18, 2014

Exercise and Weight Loss
Peter Dazeley/Getty Images

When it comes to losing weight, most of us follow a simple formula: burning more calories + eating fewer calories = weight loss. Exercise is one way we try to burn more calories, so we hit the gym or pick up a pair of weights thinking we’ll eventually see the number on the scale inch its way down. Unfortunately, it doesn’t always work that way, something that often frustrates new exercisers. If you’re doing all this exercise, you should be losing weight, right?

The truth is, exercise is a complicated business and there are a number of things that can affect how many calories you burn. Knowing what those are will help you set realistic goals and get the most out of your workouts.

How Many Calories Are You Really Burning with Exercise?

If you’re trying to lose weight with exercise, you may have used an activity calculator to determine how many calories you’re burning. For example, if you’re 165 lbs and you go jogging for 30 minutes, this calculator shows you’ve burned about 371 calories. Not bad for a 30-minute workout, you might think, but are you getting the whole story? Not exactly. There are a few other things to consider when it comes to exercise and weight loss.

1. Net Calories vs. Gross Calories: Most calculators use activity, duration of your workout and your weight to come up with an estimate of calories burned, or what is known as gross calories burned. What we forget to factor in are the calories we would’ve burned if we weren’t exercising, also known as the net calories burned. If you jogged during a time you normally watch TV, you’re still burning more calories than you were, but you need to subtract the calories you would’ve burned while watching TV in order to get a more accurate calculation.

It may seem like a small difference, after all you may burn more than 300 calories jogging and only about 40 calories watching TV. This difference becomes important, however, when you’re trying to predict weight loss. Those 40 calories, if unaccounted for, can add up to fewer pounds lost.

What you can do: If you’re tracking calories burned with exercise, you’ll get a more accurate number by subtracting the calories you would’ve burned if you weren't working out. For example, if you burned 200 calories while walking for 20 minutes and would've burned 50 calories if you sat at the computer during that time, your net calories burned would be 150. You can calculate your calories with this activity calculator.

2. Exercise Intensity: You probably know that taking a leisurely stroll won't burn as many calories as, say, running a mile as fast as you can. How hard you work plays a role in how many calories you’re burning. Some calculators, especially those on cardio machines like treadmills and elliptical trainers, do take into account things like pace, resistance and incline. We also know the relative intensity of a number of activities, but using this information to estimate how much weight you’ll lose is tough.

For example, if you were to burn 2,000 calories a week with a walking program, you might expect to lose about 6 pounds of fat after 10 weeks of exercise. The problem is, this assumes you burned exactly 2,000 calories each week and that 6 pounds of fat would generate exactly 6 pounds of body weight loss, which isn’t always the case.

What you can do: The formulas we use to calculate exercise intensity and calories burned aren't 100% accurate. Rather than rely solely on those numbers, learn how to monitor your intensity using the talk test, perceived exertion and/or target heart rate. You'll find your own limits while keeping track of how hard you’re working. You can get the most out of your workouts by:

  • Varying your intensity: The harder you work, the more calories you burn, but if all your workouts are high intensity, you run the risk of overtraining and injury. By incorporating a variety of intensity levels, you’ll stimulate different energy systems while giving your body a break from too much high-intensity exercise. Interval training is a great option for working harder while still getting some rest time.
  • Using a heart rate monitor: A heart rate monitor is a great tool for getting an accurate view of your heart rate throughout your workout while keeping you on pace. Many monitors also show calories burned during your workout and you can use that number to compare different workouts and different intensity levels.

Next Page: More about exercise and weight loss

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