Intermittent fasting, a type of weight-loss fad diet prized by some celebrities, does not extend life expectancy, a major study suggests.
Instead, eating less overall helped increase longevity, as experts found in a unique study in mice.
But skinny people looking to trim their love handles, beware: It’s essential not to lose weight while doing so, as this could have the opposite effect, depending on the results.
In an experiment with 1,000 unrelated mice, American researchers set out to explore exactly how diets influence lifespan.
The mice were unrelated, rather than the laboratory standard of closely related animals, to better mimic a human population.
Intermittent fasting, a type of weight loss diet popular among some celebrities, doesn’t actually prolong lifespan, a major study suggests.
The rodents were divided into five groups, one with unlimited food all the time, two where they were given 60 or 80 percent of their regular food, and two where the mice were given an unlimited amount of food but only one or two days a day. day. week.
They were then studied for the rest of their lives.
Publish your results on NatureThe researchers found that mice on a 60 percent restricted diet lived longer on average, about 34 months.
In human terms, this is equivalent, very broadly, to a person being around 80 years old.
Mice on the 80 percent diets lived the next longest, 30 months on average, equivalent to 80 years in people.
In comparison, rodents on intermittent fasting diets only lived an average of 28 months, roughly 70 years in human terms.
The animals that were given the freedom to eat whatever they wanted lived the shortest amount of time, 25 months on average, the equivalent of reaching 70 years for a person.
This result meant that eating fewer calories had a greater impact on lifespan than fasting and this was true regardless of how fat or fit the individual mice were when the results were analyzed on a mouse-by-mouse level.
And in a discovery that surprised researchers, it wasn’t weight loss from eating fewer calories that seemed to have this effect.
In fact, it was the mice that lost the least weight despite their very restricted diet that tended to live the longest in the experiment.
In contrast, those who lost weight on these diets tended to have low energy and weakened immune and reproductive systems, as well as shorter lifespans.
Professor Gary Churchill from the Jackson Laboratory in New Jersey said: “Our study really points out the importance of resilience.”
And he added: “The most robust animals maintain their weight even in the face of stress and caloric restriction, and they are the ones that live the longest.”
“It also suggests that a more moderate level of calorie restriction may be the way to balance long-term health and life expectancy.”
However, the researchers said that another key part of their study, and the reason they used genetically diverse mice for the experiment, is that there was a large variation in lifespan between all the groups of mice.
For example, even among mice on calorie-restricted diets, individual lifespans ranged from a few months to four and a half years.
By further analyzing the mice, the researchers found genes that increased resilience while helping to maintain body weight, body fat percentage, and immune cell health during periods of stress that they lived longer.
Experts said this showed that although diet could be used to influence lifespan, at the end of the day an individual’s longevity could be at the mercy of genes.
Professor Churchill said: “If you want to live a long time, there are things you can control during your life, such as diet, but really what you want is a very old grandmother.”
Jennifer Aniston (left) and Nicole Kidman (right) are two startups previously linked to intermittent fasting.
From the Kardashians to Prime Minister Rishi Sunak, it seems like almost everyone has tried fasting. Its defenders say that the tendency to diet extremes increases energy levels and helps eliminate fat. Some opt for 24-hour fasts, while others cram all of their daily meals into a short six-hour period in a bid to reap a host of supposed health benefits. But some studies have suggested that skipping meals and delaying breakfast could also increase the risk of diabetes and even lead to a heart attack.
This study was conducted in mice and therefore has limited application in people.
But Professor Churchill said the results had important implications for research into increasing lifespan in humans, a field that typically looks at how metabolism works as a measure of biological age.
“While calorie restriction is generally good for life, our data show that losing weight with calorie restriction is actually bad for life,” he said.
“So when we look at human trials of longevity drugs and see that people are losing weight and have better metabolic profiles, it turns out that that might not be a good marker of their future life expectancy at all.”
Several famous faces have used or supposedly used intermittent fasting over the years.
Actors Mark Wahlberg (left) and Chris Pratt (right) have also used intermittent fasting to lose weight for their roles.
Benedict Cumberbatch and former Prime Minister Rishi Sunak have also been linked to the diet in the past.
Kourtney Kardashian is also among the celebrities who have joined the fasting trend since she rose to fame in the early 2010s. She is pictured here earlier this year.
These include the likes of Jennifer Aniston, Benedict Cumberbatch, Kourtney Kardashian and Nicole Kidman.
In October 2019, Aniston said she doesn’t eat breakfast and only starts eating after noon.
Mark Wahlberg is also a fan of intermittent fasting and is famous for not eating his first meal until midnight. Stop eating at 6 pm.
Actor Chris Pratt also credits intermittent fasting with helping him lose 60 pounds (27 kg) for action star roles.
It’s not just the Hollywood elite, former Prime Minister Rishi Sunak also joined the trend, stating in 2022: “I do intermittent fasting, so most days I don’t have breakfast at all.”
However, some studies have found that these types of diets could increase the risk of diabetes and even cause a heart attack.
