Why exercising doesn't always make you lose weight
Multilevel metabolic adaptation to exercise training
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Liver and kidney volumes decreased by 5% after aerobic exercise.
Most assume only fat or muscle changes with exercise — but vital organs shrink too, reducing metabolic rate. No prior human study showed this link in exercise-induced weight loss.
Practical Takeaways
If your goal is weight loss, prioritize diet over exercise — create a calorie deficit through food, not just movement.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Liver and kidney volumes decreased by 5% after aerobic exercise.
Most assume only fat or muscle changes with exercise — but vital organs shrink too, reducing metabolic rate. No prior human study showed this link in exercise-induced weight loss.
Practical Takeaways
If your goal is weight loss, prioritize diet over exercise — create a calorie deficit through food, not just movement.
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 (6)
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.
In overweight adults, regular aerobic exercise does not lead to eating more food or increasing the calories burned from digestion. Instead, the body's overall energy balance changes mainly because it burns fewer calories during daily activities.
When overweight adults walk for 12 weeks at a targeted energy expenditure level, their bodies burn fewer calories at rest and during sleep, reducing total energy expenditure by about 100 calories per day, which offsets some of the calories burned through exercise.
In overweight adults, regular aerobic exercise is linked to a small decrease in the size of the liver and kidneys, which might lower the body's resting energy use because these organs consume a lot of energy. This connection does not prove that exercise causes the lower metabolic rate.