How many calories you burn during a workout depends on numerous factors, including your size, intensity level, fitness level, activity and body-fat ratio. For example, a 125-pound person walking for 30 minutes at a brisk 4 mph burns 137 calories in 30 minutes, while her 185-pound friend burns 200 calories in that same amount of time.
What constitutes a good calorie burn for you isn’t necessarily what constitutes a good calorie burn for everyone else. If you are at a healthy weight and your friend is overweight, he may burn more calories doing the same workout – but that doesn’t make his session “better” than yours. Beginners may not achieve the fast runs and vigorous intensities required to burn 500 or more calories in an hour, and that’s OK. Over time, you can work up to a higher burn rate, but be patient; going too hard, too soon in an attempt to burn a large number of calories can lead to burnout and injury. Your goal should be to increase physical activity, not to achieve a particular number of calories burned.