Intermittent fasting practiced by celebrities such as Elon Musk, Jennifer Aniston and Kourtney Kardashian does not make you younger, according to a new study.
Scientists found no concrete evidence to suggest missing out on food for long periods is effective at preventing ageing.
Two treatments, one of which targets how cells produce energy and another which targets a growth hormone, are also effective at preventing ageing, according to researchers.
Instead, they appear to slow down the process because they are good for you overall rather than because they specifically target the ageing process.
Earlier research has used lifespan as an indirect measure of ageing, but the German research team said this is a flawed approach.
Friends star Jennifer Aniston previously said she “noticed a big difference” by going without solid food for 16 hours.
Guardians of the Galaxy actor Chris Pratt said he would not eat before noon to get on shape for superhero roles.
Reality star Kourtney Kardashian said she would not eat past 7pm at night and then waited until around 10:30am or 11am to eat the next day.
But now scientists are saying this approach does not slow the ageing process.
It is often assumed that if an animal lives longer it will age more slowly, but many creatures die from specific diseases rather than old age in general, scientists said.
For example, around 90 per cent of mice die from tumours that form in their bodies as they grow old.
However, if the whole genome for factors that help mice to live long lives is examined, researchers would likely find many genes that suppress tumour development - and not necessarily ones that play a general role in ageing, the experts said.
For the study, the team carried out a through health check in mice which looked at age-related changes to a wide range of bodily functions.
The check gave the team an “exact description” of the state of the animal at the time they were examined.
At different stages of life, the team compared how parameters changed at different stages of life and whether these changed more slowly when the creatures were given the treatments.
The team say the way the study was designed made it possible to work out whether the natural ageing process can be slowed and the deterioration of important body functions can be slowed.
They said the results were “unambiguous” and showed that even when older mice appeared younger than they were, this had occurred for other reasons.
Dr Dan Enhinger, from the German Centre for Neurodegenerative Diseases and an author of the study, said: “There is no internal clock of aging that you can regulate with a simple switch - at least not in the form of the treatments studied here.
“The fact that a treatment already has its effect in young mice – prior to the appearance of age-dependent change in health measures – proves that these are compensatory, general health-promoting effects, not a targeting of aging mechanisms.”
The team now want to look at the effects of other treatments experts believe can slow ageing.
The findings were published in the journal Nature Communications.
