Many exercise machines, including ellipticals, will give you a reading of how many calories you are burning as you exercise. Some will also distinguish how many of those calories came from fat. While your goal for exercising may be to burn fat, differentiating what type of calories you are burning is not as important as you might think.
Ratio of Fat Calories Burned at Different Intensities
When you exercise, your body burns calories that come from a combination of fat, protein and carbohydrates. At lower intensities, approximately 60 percent of the calories or energy you burn will come from stored fat and the rest comes from carbohydrates and protein in your body that have yet to be converted to fat. At higher intensities, those numbers switch and only 35 percent of the calories you burn come from fat, while the larger amount comes from carbohydrates and protein.
Fat-Burning Zone Myth
While you may be tempted to exercise at a lower intensity, or what many machines refer to as the "fat-burning zone," to burn more fat calories, you’ll actually burn more calories overall if you exercise at a higher intensity. For example, a 160-pound person jogging at a 5-mph rate will burn 606 calories overall, of which 363 calories will come from fat. If that same person jogs an hour at a 8-mph pace, however, she will burn 861 calories. While only 301 of those will be from fat, she’ll still be burning 261 more total calories, and when you are trying to lose weight, it’s the overall calorie burn that matters.
Something else to note when you are considering the type of calories you are burning is that all the calories you consume, including carb calories, will eventually turn to fat. When you eat carbohydrates, they're metabolized in your body into glucose and delivered to your body cells to keep them healthy. Any extra carbohydrates that are not needed by your system are eventually converted into fat. Exercising will burn these extra carb calories and prevent them from metabolizing into fat.
Machine Console Irregularities
It’s important to remember that readouts on exercise machines, including ellipticals, are only estimates and may not truly reflect how many calories you’re actually burning. Machines take into account how many calories an average person of your weight or age may burn at a given speed, but they don’t factor in your metabolism, muscle mass, conditioning or other personal characteristics that play a role in calorie burn. If you’re looking to accurately count how many calories you’re burning, use a heart rate monitor instead, which will give you a personalized reading.
- American Council on Exercise: Will I Lose Body Fat More Efficiently by Performing Aerobic Workouts at a Low, Rather Than a High, Intensity?
- Mayo Clinic: Exercise for Weight Loss: Calories Burned in 1 Hour
- American Council on Exercise: 4 Exercise Myths That Won’t Go Away
- Diabetes Health: Why Eating Too Many Carbs Makes You Fat
- The Seattle Times: Don’t Believe Everything Your Exercise Machine Tells You
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