An hour of cardio and 600 kcal (calories) gone? A newer review says it is not that simple.
Short answer: You burn less than the watch says. In a review of 18 aerobic trials (Pontzer and Trexler, Current Biology 2026) the body claws back about 70% of the calories burned in cardio somewhere else. If the watch shows 600 kcal, daily burn often rises by something like 180.
What the 18 trials found
Pontzer and Trexler went through 18 aerobic interventions in Current Biology (2026). The conclusion is harder than people expect.
The body makes up about 70% of the calories "burned in cardio" somewhere else. It lowers resting metabolism, you move less outside the session, it saves energy at night, it adjusts hormones. The watch shows 600 kcal? In reality the day's expenditure often rises by something like 180.
When does this hurt most? In a deep deficit, with long regular activity, and in contest prep. There the compensation can approach 100%.
There is one point the loud gym takes rarely finish. For lifting, this compensation is clearly lower, even though we have less data on it than on cardio. The body is less willing to save on building muscle, on the sleep after training, or on a session that is less predictable. That is why lifting can give you a similar result at a lower total burn. The minimum effective version is in strength training: one hour a week.
Cardio is not bad. It is good for the heart, the head and fitness. It is a weak main tool for fat loss.
The order does not change. Food is on top: a calorie deficit. Nobody has found a shortcut. Then strength training, which keeps muscle and resists compensation better. Take cardio as a bonus, not as the base. Walking, which is easier to keep and harder to "make up" in the same way, is in how many steps a day. Losing fat with little formal exercise is in lose weight without exercise. Whether the cardio is fasted does not rescue the arithmetic: fasted cardio.
If fat loss is built on the treadmill, it may be built on the wrong lever. The question I would rather ask: when did you last log a full day with no exceptions, including the square of chocolate, the two spoons of oil and the taste of sauce?
Frequently asked questions
How does the body claw back calories burned in cardio?
It lowers resting metabolism, you move less outside the session, the body saves energy at night, and it adjusts hormones.
When is the compensation after cardio largest?
In a deep deficit, with long regular activity, and in contest prep. There it can approach 100%.
Does the same thing happen with strength training?
Compensation is clearly lower for lifting, even though there is less data than for cardio. That is why lifting can give a similar result at a lower total burn.
Is cardio useless for fat loss?
Cardio is good for the heart, the head and fitness. As the main fat loss tool it is weak.
What should I focus on instead of cardio?
Food first: a calorie deficit. Then strength training, which keeps muscle and resists compensation better. Take cardio as a bonus on top.
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Apply for coaching Get the free Fat Loss KitSources, so you can check:
1) Pontzer and Trexler (2026), Current Biology. DOI: 10.1016/j.cub.2026.01.025. Review of 18 aerobic interventions: the body compensates about 70% of calories burned in cardio
Martin Barna
Online nutrition and fitness coach. Since 2013 I have helped 600+ people lose fat and keep the result. Science, not crash diets.
Apply for coachingThis article is for information only. It is not medical advice. If you have a health condition, talk to your doctor.