Table of Contents
Understanding Calorie Burn
Calories burned during exercise are determined by the intensity of the activity, your body weight, and the duration. The Metabolic Equivalent of Task (MET) system provides a standardized way to compare energy expenditure across different activities. One MET represents the energy cost of sitting quietly, approximately 1 kcal per kilogram of body weight per hour (or 3.5 ml of oxygen per kg per minute).
An activity with a MET value of 10 burns 10 times as many calories as sitting at rest. This system allows accurate comparison and calculation across hundreds of physical activities, from gentle stretching (2.0 METs) to sprinting (23.0 METs).
MET-Based Calorie Formula
MET Values by Activity
| Activity | MET | Cal/30min (170 lb) |
|---|---|---|
| Walking (3 mph) | 3.5 | 135 |
| Running (6 mph) | 9.8 | 377 |
| Cycling (moderate) | 8.0 | 308 |
| Swimming (moderate) | 7.0 | 270 |
| Weight Training | 6.0 | 231 |
| Yoga | 4.0 | 154 |
Factors Affecting Burn Rate
- Body weight: Heavier individuals burn more calories for the same activity and duration.
- Fitness level: More fit individuals may burn slightly fewer calories at submaximal intensities.
- Age: Metabolic rate decreases with age, slightly reducing calorie burn.
- EPOC: High-intensity exercise creates an "afterburn" effect that increases calorie expenditure for hours post-workout.
- Temperature: Exercising in extreme heat or cold increases calorie burn slightly.
Frequently Asked Questions
How many calories do I need to burn to lose one pound?
One pound of body fat contains approximately 3,500 calories. To lose one pound per week, you need a daily caloric deficit of about 500 calories, achieved through a combination of reduced food intake and increased physical activity. This is a simplified model; actual fat loss involves complex metabolic factors.
Are calorie burn estimates accurate?
MET-based estimates are generally within 15-20% of actual calorie expenditure for most people. They tend to overestimate for very fit individuals and underestimate for heavier or less fit individuals. Heart rate monitors and power meters provide more personalized estimates.