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Aging Cell

Fasting schedule extends life and improves swimming in killifish

Median lifespan rose 41.8% versus daily feeding when males and females were analyzed together, while older fish of both sexes swam faster.

Paper by Sonia Sandhi, Hannah M. Somers, Matthew Cox, +12 more authorsRomain Madelaine · Hannover Biomedical Research School Medizinische Hochschule Hannover Hannover Germany
Graphical abstract from Aging Cell
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Graphical abstract. Sandhi et al., CC BY

Our read

Interventions
Studied:
Experiments in male and female African turquoise killifish, lifelong, against daily-fed control fish (Randomized)
What changed:
Fasting increased median lifespan by 53.08% in males and 21.18% in females compared with daily feeding
The catch:
Reduced calorie intake could explain benefits attributed to fasting timing
In the record:
One of 822 papers on intermittent fasting on record: 198 with results in people, 211 in animals. Its result on lifespan agrees with 44 of 52 other findings on record; 2 point the other way and 6 found no change.
Why it’s aging research:
It studies an intervention with evidence of extending healthy life.

Editor of record: Boris Djordjevic · AgingResearch.News

Paper
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Male and female African turquoise killifish of the GRZ strain were randomly assigned at 30 days after hatching to lifelong feeding regimens in an animal experiment. After an adjustment period, one fasting group repeated two days without food followed by one feeding day. Compared with daily-fed controls, this schedule extended lifespan in both sexes and improved swimming performance in older fish. It also reduced growth and reproductive output. Four fasting days followed by three feeding days instead reduced median lifespan by 10.3% versus daily feeding.

Muscle aging differed by sex: males gained muscle fibers, while females kept similar fiber numbers but developed larger fibers. The beneficial schedule partly reduced these changes and maintained a youthful range of fiber sizes in both sexes.

Why it matters

Age-related muscle decline contributes to frailty. These findings highlight the importance of considering sex when studying dietary approaches to preserving muscle function during aging.

Caveats

Swimming tests excluded fish that did not swim. The results came from one killifish strain, not from people.

Where the evidence stands

Intermittent fasting

Worms or flies, mice and humans: replicated by independent labs. Cells: a single group.

C, W, M, H: cells, worms or flies, mice, humans. Dark: independent labs found the same change there. Light: one lab or one study. Outline: nothing yet.

Labs are independent when their papers share no last author and no institution.

Against: findings that point the other way from most findings on the same outcome.

Company ties: findings with an author at a company, or from a paper whose competing-interests statement declares ties to one.

  • 236 independent labs in 49 countries
  • 91 findings against
  • Funders: National Institutes of Health and others
  • 48 of 1,001 findings with company ties

Insulin/IGF-1 signaling

Worms or flies: replicated by independent labs. Cells, mice and humans: a single group.

C, W, M, H: cells, worms or flies, mice, humans. Dark: independent labs found the same change there. Light: one lab or one study. Outline: nothing yet.

Labs are independent when their papers share no last author and no institution.

Against: findings that point the other way from most findings on the same outcome.

Company ties: findings with an author at a company, or from a paper whose competing-interests statement declares ties to one.

Includes the processes named after it and trials of drugs aimed at it.

  • 104 independent labs in 28 countries
  • 5 findings against
  • Funders: National Institutes of Health and others
  • 8 of 154 findings with company ties

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