Short answer
Exercise calorie estimates are averages and can run 10 to 20 percent high. If your target already includes exercise through an activity level, do not eat the calories back. If it does not, eating back about half is a cautious start.
1. Two ways to set your target
- Method 1: activity level includes exercise. Choose an activity level in the Calorie Calculator that reflects your usual week. Your target already contains the calories from exercise, so eat the same target every day and do not eat workouts back.
- Method 2: sedentary base plus exercise. Choose the sedentary level for a low base, then add back some of the calories each workout burns.
2. Worked example for Method 2
A 35-year-old man, 80 kg and 178 cm, has a BMR of about 1,743 and a sedentary maintenance of about 2,091. For a 500-calorie deficit his base target is 1,591 calories. A 30-minute run at 6 mph (MET 9.3) burns 9.3 × 3.5 × 80 ÷ 200 × 30 = about 391 calories.
| Choice | Calories to eat on a run day |
|---|---|
| Eat back nothing | 1,591 |
| Eat back half (about 195) | 1,786 |
| Eat back all 391 | 1,982 |
If the estimate is 20% too high, the real burn is about 313 calories, so eating all of it back would leave a much smaller deficit than planned.
3. Why caution makes sense
- MET-based estimates and wearables are averages and can be off by 10 to 20 percent.
- People tend to move a little less on other parts of the day after hard workouts.
- Gross calories include what you would have burned resting. Net calories are a fairer measure of the extra energy used.
4. How to check
Pick one method, follow it for two to three weeks and compare your weekly average weight with what you expected. If your weight is not changing as planned, change the amount you eat back, not the method.
5. Frequently asked questions
Should I eat back the calories I burn exercising?expand_more
Only if your target does not already include your exercise. A common cautious start is about half.
Do I eat back calories if I chose a higher activity level?expand_more
No. Exercise is already included in the activity factor, so eating it back counts it twice.
Are fitness tracker calories accurate?expand_more
They are estimates and can differ from the true figure by 10 to 20 percent.
What is the difference between gross and net calories burned?expand_more
Gross includes resting calories during the activity. Net subtracts them and is a fairer measure of the extra energy exercise used.