You fuel your body with calories from carbohydrates, fat and protein, but your body prefers to burn energy from carbohydrates and fat during exercise. The intensity of your workouts affect which fuel your body relies most heavily upon. For example, the higher the intensity of an activity, the more carbohydrates your body burns. However, less intense exercise is more dependent on a different fuel source.
Identification
The primary source of energy during low-to-moderate aerobic exercise is fat, which accounts for approximately 60 percent of the calories burned during activity, according to the American Council on Exercise. Your body will burn circulating fat from food before tapping into stored fat. Carbohydrates convert to glycogen to provide the remainder of the fuel used for moderate exercise. If glycogen is not available, your body may use protein for fuel, but this is more likely during higher intensity exercise.
Effects
Although low-to-moderate exercise gets most of its fuel from fat, moderate activity has the greater fat-burning effect, continuing to burn fat as fuel for a few hours after you stop exercising. Therefore, moderate exercise is more effective for weight management than low-intensity exercise. Moderate physical activity also burns more calories overall than low-intensity activities, and the number of calories you burn is more important for managing weight than the type of fuel used during exercise.
Options
You know you're exercising at moderate intensity when your heart rate goes up noticeably, but not to the extent that you can't carry on a conversation. Walking, for example, makes a flexible exercise option that allows you to easily control your intensity. If you're new to exercise, you can start with slow walking and gradually increase your intensity to a moderate level. Another option is to alternate intervals of slow walking with faster walking, which combines low and moderate-intensity exercise in one workout. You're not limited to walking; choose another activity you enjoy, whether it's swimming, hiking, jogging, sports or a combination of several options, and work out at an intensity that matches your current fitness level.
Considerations
Regular exercise will help you burn fat and carbohydrates, but ultimately what it does is burn calories. A calorie excess leads to weight gain, while a calorie deficit can help you lose weight. You can also use exercise to help you maintain your current weight if you balance the number of calories you consume with the number you burn. Low-to-moderate exercise is generally safe for most people, but get clearance from your doctor before working out, particularly if you have a history of heart problems.
References
- American Council on Exercise: Will I Burn Fat More Efficiently by Performing My Aerobic Workouts at a Low, Rather Than a High, Intensity?
- American Academy of Orthopaedic Surgeons: Sports Nutrition
- Bodybuilding: Understanding the Science Behind Interval Training and its Application to Fat Loss
- Mayo Clinic: Exercise Intensity: Why it Matters, How it's Measured
- Bodybuilding: Which Cardio Methods Melt Fat the Fastest?
- Mayo Clinic: Aerobic Exercise: Top 10 Reasons to Get Physical
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