Best time of day to eat if you want to live longer, according to longevity expert
If you're trying to follow a healthier lifestyle in 2025, there's an awful lot to think about. Getting more sleep and exercise are obvious objectives, while drinking less alcohol and eating a healthier and more balanced diet are also things everyone agrees will benefit your health.
But one thing you don't hear as often is the time at which you eat. You might think that eating an avocado is good for you whether you eat it at 3pm or 10pm right? But many experts say it's actually very important to think about when you eat, and not just what you eat.
This is what experts in improving your health and living a longer life with more healthy years have to say on the subject.
Valter Longo, director of the Longevity Institute at the University of Southern California, told the Zoe podcast that fasting periods mean the body enters "maintenance mode" which means "the body starts to age more slowly" and "might even reduce biological age".
Two simple rules Dr Longo suggests we follow are:
Eat all the food we consume in a day within a 12-hour period
Eat the last of that food three hours before your bedtime.
Dr Longo says there can be a difference of 20 years in a person's chronological age (ie how old they are according to the number of years they've been alive) and their biological age, according to scientific studies. And this can mean that your life expectancy will be longer. For example, a 65-year-old with a biological age of 40 is likely to live "a lot longer" than a 40-year-old with a biological age of 65.
He says that fasting "will revolutionize gene expression" more than anything else you can do to your body, "meaning if you fast a person for, let's say, five days it'd be hard to find something else that causes more changes in the body". He says that after fasting for three or four days, the brain "starts functioning both on glucose and on ketone bodies, and the heart can function using fatty acids and other organs" and that cells begin to rid themselves of the "junk" that has accumulated over time.
However, he said that if people are not able or willing to fast for five days, that "time-restricted eating" is also effective, saying: "The 12-hour time-restricted eating is the one that I never met a doctor or anybody that argue with." Asked outright on the Zoe podcast whether this would "actually affect the aging processes... that could make us stay healthy for more years", Dr Longo said: "The mouse studies will indicate yes. I think we're starting to see some studies indicating reduced biological age, but I don't know if anybody's ever tested the, say, 11, 12 hours of eating."
Zoe founder Prof Tim Spector told the same podcast that a Zoe study which asked people to fast for 14 hours found that "a third of people found it really easy to do this, and they actually carried on well past the three weeks". He said: "Those people got real benefits in mood and energy. They lost weight and waist circumference improved and they actually had less hunger by doing that. So they really liked it. A third of people never found it too much and they didn't actually get started and a third started and sort of gave up.
"There are certain people that it probably really suits and they feel very comfortable, it feels natural to them and they get into it and I think they will get benefits. Some people do find it rather hard to go long periods without eating. So I'm all for this not-too-strict-a-time-restriction eating, but it is not necessarily for everybody. We didn't try the 12 hours, so it could have been for most people, even easier to do the 12 hours."
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Zoe chief scientist Dr Sarah Berry said there is "more and more evidence to show that if you can eat within a smaller eating window it benefits your health" and that these benefits included "levels of inflammation, blood pressure, lowering cholesterol, improving insulin sensitivity, reducing weight, reducing your risk of chronic diseases".
She said an eating window "can significantly benefit your health. It can improve your energy levels, it can improve your mood. Really interestingly, it can improve your hunger, as in you feel less hungry by limiting to a 10 hour eating window. But it can also help you reduce weight".
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And Prof Spector added: "Gut microbes get a real kick out of having a rest overnight. And they need time to recover and repair."
Of course, there are lots of factors that influence how long you will live and your life expectancy, including genetic and environmental ones. But, according to Dr Longo, Prof Spector and Dr Berry, there is growing belief that consuming your food within a shorter "window" of time to allow your insides to rest more is one of them.