Answers
Should I eat back the calories I burn exercising?
Written by the GymStreak coaching teamUpdated
Short answer
Not all of them. Calorie burn estimates from watches and apps are often off by 20% or more, and your body partly adapts to extra activity. When trying to lose fat, eat back none or about half, then adjust from your weekly average weight over two to three weeks. When bulking, eating more back makes sense.
01 / Accuracy
Why the numbers are unreliable
A study of seven wrist-worn devices found heart rate was measured fairly well, but none of them estimated energy expenditure within 20% error, and some were off by far more.
Total daily energy use also doesn’t rise one-for-one with activity. A study of over 300 adults found that total energy expenditure levelled off at higher activity levels, as the body adapts. And people can overestimate how much they move: in one study of people with obesity who said they couldn’t lose weight on low-calorie diets, participants overreported their activity by about half.
02 / What to do
A simple approach
| Goal | Exercise calories |
|---|---|
| Losing fat | Eat back none, or about half on big training days. |
| Maintaining | Eat back about half, adjust to keep your weekly average steady. |
| Gaining | Eat back most of them, and more if your weight isn’t rising. |
Easiest of all: set one daily target that already includes your usual training (TDEE calculator), then adjust it every two to three weeks from your average weight.
03 / Adjusting
Let your weight trend decide
Your weekly average weight is the real measure. If it isn’t moving the way you want after two or three weeks, change your daily target by about 100 to 200 kcal, not your exercise-calorie rule. Weigh in most mornings to get a reliable average (how often to weigh yourself).
04 / How Spot helps
How Spot helps
If your weight trend says your target is off, ask Spot to change your calorie goal; its daily briefing shows your weight trend next to yesterday’s food. Workouts and nutrition also sync with Apple Health and Health Connect.
05 / FAQ
Frequently asked questions
Are Apple Watch calorie estimates accurate?
Wrist devices measure heart rate fairly well, but their calorie estimates are much less accurate; in one study none of the seven devices tested was within 20%.
Do I need to eat back calories on a bulk?
Usually yes, or simply set a higher daily target. If your weight isn’t rising slowly, eat more.
Does lifting burn many calories?
Less than people expect during the session. Its bigger value on a diet is keeping muscle; let your weight trend tell you whether your intake is right.
Sources
- Shcherbina A, Mattsson CM, Waggott D, et al. Accuracy in wrist-worn, sensor-based measurements of heart rate and energy expenditure in a diverse cohort. J Pers Med. 2017;7(2):3.
- Pontzer H, Durazo-Arvizu R, Dugas LR, et al. Constrained total energy expenditure and metabolic adaptation to physical activity in adult humans. Curr Biol. 2016;26(3):410-417.
- Lichtman SW, Pisarska K, Berman ER, et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. N Engl J Med. 1992;327(27):1893-1898.
General training and nutrition information, not medical advice. If you have pain, an injury or a health condition, check with a doctor or physiotherapist.
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More answers
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Spot, the AI coach in GymStreak, answers questions like this from your own logged workouts and food, and changes the workouts in your plan for you. The app is free to download; Spot, starting and logging workouts need Premium, an in-app subscription, and the app shows your local price before you pay.