October 18, 2021

expert reaction to study looking at calorie restriction, fasting, and lifespan in mice

A study published in Nature Metabolism suggests that fasting may mediate the beneficial effects of a calorie-restricted diet in mice.

Prof Sir Stephen O’Rahilly, Director of the MRC Metabolic Diseases Unit, University of Cambridge, said:

“This paper shows that mice who ate all their calories in one short period of the day, and were then kept fasting for the rest of each day, remained healthier and lived longer than mice who were given free access to food and ate when they wanted.

“This is interesting but very hard to extrapolate to humans.  Given the striking differences between mice and humans in the speed at which the body’s processes happen, a comparable human experiment would need to have humans eat all the calories they need for a week in a single day and then starve for the next 6 days.  As mice live about 2 years and we now live to around 80, we might have to do the study for more than 50 years to test whether such a massive change to our eating habits actually benefited human longevity.  It is unlikely that this experiment will ever be undertaken.

“We know that avoiding or reducing obesity is beneficial for human health.  People find different ways of achieving this.  Some people might find that reducing their meal frequency is something that works for them.”

‘Fasting drives the metabolic, molecular and geroprotective effects of a calorie-restricted diet in mice’ by Heidi H. Pak et al. was published in Nature Metabolism at 16:00 UK time on Monday 18 October 2021.

DOI: 10.1038/s42255-021-00466-9

Declared interests

None received.