The Study
Long-term calorie restriction decreases metabolic cost of movement and prevents decrease of physical activity during aging in the rhesus monkeys
This study watched monkeys for over 10 years and noticed that those eating less moved around more and used less energy to move. But it didn’t make the monkeys eat less — it just observed what happened. So we can’t say eating less caused the changes, only that they happened together.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Monkeys that ate less for many years burned less energy while sleeping but moved more and moved more efficiently, so their total energy use stayed the same — and they didn’t slow down as they aged.
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 516 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This suggests that in primates, eating less long-term may help preserve movement and energy efficiency, potentially delaying age-related decline — but it’s not clear if this directly applies to humans.
- 2CR monkeys had 11–19% lower resting metabolism, 15–30% lower energy cost per movement, and 2x more high-intensity activity than controls; their activity didn’t drop with age, unlike controls who lost 30–40%.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Experimental gerontology
Year
2013
Authors
Yosuke Yamada, R. Colman, J. Kemnitz, S. Baum, Rozalyn M. Anderson, R. Weindruch, D. Schoeller
Related Content
Claims (6)
When people eat way fewer calories for a long time, their organs can get smaller, and that makes their body burn fewer calories overall.
Monkeys that eat fewer calories for a long time tend to move around more and stay active longer than monkeys that eat normally, even though they're taking in less energy.
Monkeys that eat less over a long time use less energy when they move around, which means their muscles work more efficiently — like a car that gets better gas mileage.
Even though monkeys on a low-calorie diet burn less energy while sleeping and eat less, their total daily energy use stays the same because they move around more and spend less energy moving, so it all balances out.
Monkeys that ate less for many years burn fewer calories while sleeping, even when you account for how much muscle they have, as if their bodies learned to use less energy just to stay alive.
Monkeys that eat fewer calories over many years stay more active as they age, while monkeys that eat normally become much less active over time.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.