From flies and worms to rodents and primates, numerous studies in laboratory animals have shown that calorie restriction extends lifespan. But translating calorie restriction to people over the long-term is all but impossible.
However, scientists say there’s another approach that can provide much of the benefit of calorie restriction without all the severe restriction.
I’m talking about time-restricted eating. Here’s what you need to know…
Many studies in a variety of lifeforms demonstrate that a considerable reduction in calories while – and this is key – maintaining intake of all necessary nutrients, delays aging and extends lifespan.
Until recently it wasn’t clear if time-restricted eating could extend life, but a study published in the journal Nature last year showed it “robustly extended fly lifespan…”
Scientists at the University of Texas Southwestern Medical Center carried out an exhaustive four-year investigation involving hundreds of male mice to see if both methods combined – calorie restriction and time restricted eating– would produce even better results.
They also tested the impact of a third factor – circadian rhythms.
Lifespan Boosted by 35 Percent
New research suggests the body’s daily, or circadian, rhythms may play a big part in longevity, so the scientists tested this theory with laboratory mice.
For the study, mice were housed with automated feeders to control when and how much they could eat.
One group ate as much as they wanted, whenever they wanted, while five other groups had their calorie intake reduced by 30 to 40 percent. Of these, one group ate over 24 hours, a second was restricted to a two-hour window, and a third was restricted to a twelve-hour window.
Next, the researchers divided the time-restricted mice to eat either during the night, when they’re most active, or during the day. The findings, published in the journal Science in May, revealed some interesting results. For example:
- Mice in the unrestricted feeding group lived their normal lifespan of 800 days.
- Mice in the calorie restricted feeding group who were eating around the clock saw an increase in lifespan by ten percent to 875 days.
- Mice in the calorie restricted feeding group who were eating only during the day enjoyed a 20 percent boost in longevity to 959 days.
- Mice in the calorie restricted feeding group who were time-restricted to eat only during the night had their lives extended to 1,068 days, a whopping 35 percent increase over the unrestricted eaters.
When You Eat Matters
Neuroscientist and geneticist Joseph Takahashi, who led the research, said, “We have discovered a new facet to caloric restriction that dramatically extends lifespan in our lab animals. It’s pretty clear that the timing of eating is important to get the most bang for your buck with calorie restriction.
“If these findings hold true in people, we might want to rethink whether we really want that midnight snack.”
His colleague Dr. Victoria Acosta-Rodriguez added, “Our findings serve as a proof-of-principle for investigating circadian clocks as potential targets to delay aging.”
Further work by the team showed that calorie restriction, especially when combined with time restriction during the active period, offsets aging-induced genetic changes that promote inflammation and lower the regulation of metabolism.
Rafael de Cabo, a gerontology researcher at the National Institute on Aging (NIA) said the paper “is a very elegant demonstration that even if you are restricting your calories but you are not [eating at the right times], you do not get the full benefits of caloric restriction.”
Sai Krupa Das, a senior nutrition scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging, described the paper as “a very promising and landmark study.”
Of course, this begs the question, what does successful calorie restriction entail?
An extremely low-calorie diet that focuses solely on nutrient dense foods. In practice, this looks like reducing your calorie intake by, gulp, 30 percent! Again, this isn’t realistic for most of us to apply in our very busy daily lives. However, there’s a silver lining…
Even Modest Calorie Reduction Works Wonders
Few would want to reduce their calorie intake by 30 percent, but that isn’t necessary. Dr. Das took part in a first of its kind, large, randomized controlled trial published in 2019, which showed that even an average calorie reduction of 11.9 percent over two years in healthy participants aged 21 to 50 improved multiple cardiometabolic risk factors such as blood fats, blood pressure, glucose control and inflammation.
Dr. Das confirmed that even a modest reduction in calories “was remarkably beneficial” for reducing signs of aging.
The current study also adds to the growing evidence for time-restricted eating, and shows it isn’t necessary to go to extremes. Eating within a 12-hour time frame during the day – the active period for humans – is good enough to offer profound benefits when it comes to your health and longevity.
Professor Takahashi himself says he’s taking a lesson from his mice and will restrict his own eating to a 12-hour period.