The Study
Multilevel metabolic adaptation to exercise training
This study watched 16 people walk a lot for 12 weeks and noticed their bodies changed — they burned less energy at rest and their organs got a little smaller. But because there was no group that didn’t exercise, we can’t say the walking caused those changes — maybe they would’ve happened anyway. So it shows a pattern, not proof.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Your body fights back when you exercise by slowing down your metabolism and making movement easier, so you burn fewer calories than you think.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 565 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — these changes cancel out a big chunk of the calories burned during exercise, making weight loss much harder than expected.
- 2Resting metabolism dropped by 74–105 kcal/day; liver and kidneys shrank by 5%; walking became 11% more efficient; daily calorie burn didn't go up much beyond what exercise added.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Communications Medicine
Year
2026
Authors
T. Knaan, Eylam Ziv-Av, G. Dubnov-Raz, I. Markus, David Peled, P. Manich, Daniel Barazany, Maayan Ramati, Gal Aziel, Chen Luxenburg, Carmit Levy, Edward L. Melanson, Y. Gepner
Related Content
Claims (10)
When people do aerobic exercise, their bodies reduce other types of energy use, such as resting metabolism and daily movement, so the total amount of energy burned in a day does not increase proportionally to the exercise performed.
When people increase their physical activity, their bodies reduce other forms of energy expenditure, such as resting metabolism and spontaneous movement, which limits the overall increase in daily calorie burn.
When you perform aerobic exercise, less than one-third of the calories you burn during the activity result in a lasting increase in your total daily calorie burn.
People who engage in physical exercise burn about 5% more energy per day than those who do not.
Overweight adults who engage in regular aerobic exercise use less oxygen when walking at a moderate pace, which reduces the amount of energy their body needs for everyday movement.
In overweight adults, doing aerobic exercise does not increase total daily calorie burn beyond what the exercise itself burns. Instead, the body adjusts by lowering the amount of energy used at rest, not by reducing everyday movement.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.