Study analysis · Communications Biology · 2018
They ate 30% less food… and lived 50% longer — but their brains shrank anyway.
Male lemurs that ate 30% fewer calories lived almost 4 extra years and got sick less, even though parts of their brains shrank faster — and they still remembered everything just fine.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study watched a group of tiny primates eat either a normal diet or less food for years and noticed that the ones eating less lived longer and had different brain changes. But it didn't prove that eating less caused those changes—maybe other things like their genes or environment played a role.
What’s the bottom line?
Scientists fed some tiny primates 30% less food than usual and watched what happened as they aged. The少吃 group lived longer and got sick less often, but their brains lost more gray matter in areas linked to memory — even though they still remembered things just as well.
How strong is this study?
The scientists did a pretty good job: they randomly picked which lemurs got which diet and checked on them every year with brain scans. But they didn't hide which diet each lemur got, and they only studied males, so we can't be totally sure the results are perfect or apply to everyone.
35 / 100
- COI disclosureconflicts of interest not disclosed
- Data availability+35/35
- Code availabilitycode not shared
60 / 100
- Randomization+20/20
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=34)+3.1/20
- Follow-up+10/10
100 / 100
54 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 518 / 100
Probability of being correct
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.
This design cannot establish causation — the findings describe an association, not a cause. Although randomization was used, blinding was unknown and the study was conducted in animals, not humans. Without blinding and with potential unmeasured confounders, causation cannot be definitively established. The design is observational in nature despite randomization due to lack of blinding and animal model limitations.
Key takeaways
- 01
Lifespan increased from 6.4 to 9.6 years (50% longer).
- 02
Grey matter shrank faster in the hippocampus and cortex.
- 03
White matter was preserved.
- 04
Memory and motor skills stayed the same.
- 05
Cancer/nephritis deaths dropped from 73% to 33%.
- 06
This suggests that in primates, calorie restriction might extend life and reduce some diseases even if it causes unexpected brain changes — and those changes don’t always hurt memory.
Surprising findings
- Caloric restriction accelerated grey matter loss in memory regions — yet cognition didn’t decline.Prior studies in rodents and even rhesus monkeys suggested CR protects or slows brain atrophy. This is the first primate study showing the opposite — and still no cognitive cost.
- Only 33% of deaths in the CR group were from cancer/nephritis — compared to 73% in controls.This isn’t just a small reduction — it’s a 55% drop in disease-related mortality. That’s more impactful than most drugs ever achieve.
Practical takeaways
Consider reducing daily calorie intake by 20–30% (under medical supervision) to potentially extend healthspan and reduce disease risk.
This study was in male lemurs only — no data on females, humans, or long-term neurological side effects. Extreme restriction can cause muscle loss, hormonal disruption, or nutrient deficiencies.
medium confidenceWhy this study matters
Lifespan jumped 50% with less food
Male grey mouse lemurs on a 30% caloric restriction lived a median of 9.6 years — up from 6.4 years in the control group. That’s a 50% increase in lifespan, with 60% fewer deaths from age-related diseases like cancer and kidney failure.
This isn’t just about mice — it’s a primate. If this translates even partially to humans, it could redefine how we think about diet, aging, and longevity.
Brain tissue shrank — but memory stayed perfect
Despite accelerated grey matter loss in the hippocampus, entorhinal cortex, and retrosplenial cortex — areas critical for memory — the calorie-restricted lemurs showed no decline in spatial or working memory on the Barnes maze or spontaneous alternation tasks.
We assume brain shrinkage = cognitive decline. This study flips that: you can lose brain tissue and still think just as well. It challenges everything we think about brain health.
White matter preserved, grey matter vanished
Caloric restriction preserved white matter in key areas like the corpus callosum (genu and splenium) and fimbria hippocampi — but dramatically sped up grey matter loss across the cerebrum. This split effect was never seen before in primates.
Most people think 'brain health' is one thing. This shows diet can help one part (connectivity) while harming another (processing units) — and the net result is still positive.
No cognitive decline? Maybe they just got better at the tests
The study notes possible 'practice effects' from annual cognitive testing — meaning lemurs improved over time simply by repeating the tasks, masking any real aging-related decline.
This raises a huge question: Did CR truly protect cognition… or did the testing itself create a false impression of resilience?
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists fed some tiny primates 30% less food than usual and watched what happened as they aged. The少吃 group lived longer and got sick less often, but their brains lost more gray matter in areas linked to memory — even though they still remembered things just as well.
Research results
Lifespan increased from 6.4 to 9.6 years (50% longer). Grey matter shrank faster in the hippocampus and cortex. White matter was preserved. Memory and motor skills stayed the same. Cancer/nephritis deaths dropped from 73% to 33%.
What this means - more context
This suggests that in primates, calorie restriction might extend life and reduce some diseases even if it causes unexpected brain changes — and those changes don’t always hurt memory.
Does chronic 30% caloric restriction extend lifespan and improve health in a primate model, and how does it affect brain structure and cognition?
In male grey mouse lemurs, 30% caloric restriction starting in early adulthood extended median lifespan by 50% (6.4 to 9.6 years), reduced age-related mortality by 60%, and lowered incidence of cancer and nephritis. It preserved white matter in key brain regions but accelerated grey matter loss in the hippocampus, entorhinal cortex, and retrosplenial cortex. Despite this grey matter atrophy, spatial and working memory performance remained unchanged.
Methods Used
Longitudinal cohort study of 34 male grey mouse lemurs (n=15 control, n=19 caloric restricted) followed for up to 13 years. Animals received either a standard diet or 30% caloric restriction from age 3.2 years. Outcomes included survival, disease incidence, cognitive testing (Barnes maze, spontaneous alternation), motor performance (rotarod), and annual MRI with voxel-based morphometry to track brain volume changes.
Main Finding
Chronic 30% caloric restriction extended median lifespan by 50% (from 6.4 to 9.6 years) and reduced age-related mortality by 60% in male grey mouse lemurs, while simultaneously accelerating grey matter atrophy in memory-related brain regions without impairing cognitive performance.
Confidence Level
High. This is a well-controlled, longitudinal primate study with randomization, longitudinal MRI, longitudinal cognitive testing, and statistical modeling of time-by-diet interactions. Sample size (n=34) is robust for a primate study, and outcomes were measured until natural death.
Study Flags
Red Flags
- •Study limited to male subjects only
- •No cognitive decline detected despite significant grey matter loss — possible practice effects from annual testing
- •MRI analysis used uncorrected p-values (p<0.005) and required large cluster thresholds, risking false positives
Surprising Findings
Caloric restriction accelerated grey matter loss in memory regions — yet cognition didn’t decline.
Prior studies in rodents and even rhesus monkeys suggested CR protects or slows brain atrophy. This is the first primate study showing the opposite — and still no cognitive cost.
Practical Takeaways
Consider reducing daily calorie intake by 20–30% (under medical supervision) to potentially extend healthspan and reduce disease risk.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 518 / 100
Probability of being correct
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.
Animal Cohort Study
Subject
Lower probability
on the GRADE evidence scale
This study watched a group of tiny primates eat either a normal diet or less food for years and noticed that the ones eating less lived longer and had different brain changes. But it didn't prove that eating less caused those changes—maybe other things like their genes or environment played a role.
Strengths
- Randomized assignment to diet groups
- Longitudinal design with repeated measures over years
- Use of MRI for objective brain volume measurements
Weaknesses
- Blinding status unknown, risking performance and assessment bias
- Small sample size limits power and subgroup analysis
- Only male subjects included, introducing sex bias
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists fed some tiny primates 30% less food than usual and watched what happened as they aged. The少吃 group lived longer and got sick less often, but their brains lost more gray matter in areas linked to memory — even though they still remembered things just as well.
Research results
Lifespan increased from 6.4 to 9.6 years (50% longer). Grey matter shrank faster in the hippocampus and cortex. White matter was preserved. Memory and motor skills stayed the same. Cancer/nephritis deaths dropped from 73% to 33%.
What this means - more context
This suggests that in primates, calorie restriction might extend life and reduce some diseases even if it causes unexpected brain changes — and those changes don’t always hurt memory.
Does chronic 30% caloric restriction extend lifespan and improve health in a primate model, and how does it affect brain structure and cognition?
In male grey mouse lemurs, 30% caloric restriction starting in early adulthood extended median lifespan by 50% (6.4 to 9.6 years), reduced age-related mortality by 60%, and lowered incidence of cancer and nephritis. It preserved white matter in key brain regions but accelerated grey matter loss in the hippocampus, entorhinal cortex, and retrosplenial cortex. Despite this grey matter atrophy, spatial and working memory performance remained unchanged.
Methods Used
Longitudinal cohort study of 34 male grey mouse lemurs (n=15 control, n=19 caloric restricted) followed for up to 13 years. Animals received either a standard diet or 30% caloric restriction from age 3.2 years. Outcomes included survival, disease incidence, cognitive testing (Barnes maze, spontaneous alternation), motor performance (rotarod), and annual MRI with voxel-based morphometry to track brain volume changes.
Main Finding
Chronic 30% caloric restriction extended median lifespan by 50% (from 6.4 to 9.6 years) and reduced age-related mortality by 60% in male grey mouse lemurs, while simultaneously accelerating grey matter atrophy in memory-related brain regions without impairing cognitive performance.
Confidence Level
High. This is a well-controlled, longitudinal primate study with randomization, longitudinal MRI, longitudinal cognitive testing, and statistical modeling of time-by-diet interactions. Sample size (n=34) is robust for a primate study, and outcomes were measured until natural death.
Study Flags
Red Flags
- •Study limited to male subjects only
- •No cognitive decline detected despite significant grey matter loss — possible practice effects from annual testing
- •MRI analysis used uncorrected p-values (p<0.005) and required large cluster thresholds, risking false positives
Surprising Findings
Caloric restriction accelerated grey matter loss in memory regions — yet cognition didn’t decline.
Prior studies in rodents and even rhesus monkeys suggested CR protects or slows brain atrophy. This is the first primate study showing the opposite — and still no cognitive cost.
Practical Takeaways
Consider reducing daily calorie intake by 20–30% (under medical supervision) to potentially extend healthspan and reduce disease risk.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 518 / 100
Probability of being correct
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.
Animal Cohort Study
Subject
Lower probability
on the GRADE evidence scale
This study watched a group of tiny primates eat either a normal diet or less food for years and noticed that the ones eating less lived longer and had different brain changes. But it didn't prove that eating less caused those changes—maybe other things like their genes or environment played a role.
Strengths
- Randomized assignment to diet groups
- Longitudinal design with repeated measures over years
- Use of MRI for objective brain volume measurements
Weaknesses
- Blinding status unknown, risking performance and assessment bias
- Small sample size limits power and subgroup analysis
- Only male subjects included, introducing sex bias
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The scientists did a pretty good job: they randomly picked which lemurs got which diet and checked on them every year with brain scans. But they didn't hide which diet each lemur got, and they only studied males, so we can't be totally sure the results are perfect or apply to everyone.
35 / 100
- COI disclosureconflicts of interest not disclosed
- Data availability+35/35
- Code availabilitycode not shared
60 / 100
- Randomization+20/20
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=34)+3.1/20
- Follow-up+10/10
100 / 100
54 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 518 / 100
Probability of being correct
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.
This design cannot establish causation — the findings describe an association, not a cause. Although randomization was used, blinding was unknown and the study was conducted in animals, not humans. Without blinding and with potential unmeasured confounders, causation cannot be definitively established. The design is observational in nature despite randomization due to lack of blinding and animal model limitations.
Standing
Who’s using this study?
The videos and claims on this site that lean on this study, and the researchers who wrote it.
1 video from Nutrition Made Simple! cite this study, drawing 1 claim from it.
- Indication only
Weak evidence — fewer than 20 studies, so treat this as a starting point, not a fact.
Evidence