Woman eating food, smiling

(Credit: Andrea Piacquadio from Pexels)

DALLAS — Eating primarily during the day instead of at night could be the key to a longer life, new research reveals. Researchers from the University of Texas Southwestern Medical Center say it’s not just what you consume, but when.

Their study finds that cutting down on fatty and sugary foods and having meals at the right time increased the longevity of mice by 35 percent. Experiments found the body clock’s daily rhythms play a big part in the benefits of a healthy diet. Rodents are nocturnal animals that are most active in the dark. Meanwhile, humans are generally livelier during the day. With that in mind, study authors say people should restrict their dining to the most active hours of the day.

In lab animals tracked over four years, a reduced-calorie diet alone extended survival by 10 percent. However, the improvement increased significantly with an exclusive nighttime feeding schedule. The combination tacked on an extra nine months to their typical two-year average lifespan.

Lead author Professor Joseph Takahashi says a similar plan for people would restrict eating to the daytime hours. Eating less is known to boost health. Studies on a variety of animals have shown it can lead to a longer, healthier life. The latest findings add to the evidence that having a hearty breakfast or lunch instead of dinner is also key — at least for humans.

Does intermittent fasting really work?

Prof. Takahashi, a molecular biologist, adds that their research helps untangle the controversy surrounding diet plans that emphasize eating only at certain times of day — which many people refer to as intermittent fasting. Although these plans may not speed weight loss in humans — according to a recent study in the New England Journal of Medicine — they can lead to other health benefits which increase the average lifespan.

Intermittent fasting diets have become increasingly popular in recent years. They include fasting on alternate days or eating only during a period of six to eight hours per day. Now, Prof. Takahashi and his colleagues have unraveled the effects of calories, fasting, and circadian rhythms on longevity. They housed hundreds of mice with automated feeders to control when and how much each animal ate for its entire lifespan.

Some could gorge as much as they wanted while others had their calories restricted by 30 to 40 percent. The latter group also ate on different schedules. Mice fed the low-calorie diet at night, over either a two-hour or 12-hour period, lived the longest.

The results suggest time-restricted eating has positive effects on the body even if it doesn’t promote weight loss. The study also found no differences in body weight among mice on different eating schedules. “However, we found profound differences in lifespan,” Prof. Takahashi notes in a media release.

Could medication also benefit our body clock?

The team hopes that learning how calorie restriction affects the body’s internal clocks as we age will help scientists find new ways to extend healthy lifespan. That could come through calorie-restricted diets or through drugs that mimic the effects of those diets.

Meanwhile, Prof. Takahashi is taking a lesson from his mice, restricting his own eating to a 12-hour period. “If we find a drug that can boost your clock, we can then test that in the laboratory and see if that extends lifespan.”

Rafael de Cabo, a gerontology researcher at the National Institute on Aging in Baltimore, says the new 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.”

Nutritionist Dr. Sai Krupa Das of Tufts University, who did not take part in the study, adds that the results highlight the crucial role of metabolism in aging. “This is a very promising and landmark study,” Dr. Sai Das says.

Decades of research has found calorie restriction extends the lifespan of animals ranging from worms and flies to mice, rats, and primates. Those experiments report weight loss, improved glucose regulation, lower blood pressure, and reduced inflammation.

However, it’s been difficult to systematically study calorie restriction in people who can’t live in a laboratory and eat measured food portions for their entire lives. Dr. Sai Das helped conduct the first controlled study in humans called CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy).

It found even a modest reduction “was remarkably beneficial” for reducing signs of aging. Scientists are just beginning to understand how calorie restriction slows aging at the cellular and genetic level. As an animal ages, genes linked to inflammation tend to become more active while those that regulate metabolism slow up.

Prof. Takahashi discovered calorie restriction, especially when timed to the mice’s active period at night, helped offset these genetic changes as they got older.

The findings appear in the journal Science.

South West News Service writer Mark Waghorn contributed to this report.

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  1. Greldon says:

    I don’t buy this one bit. Probably the correlation is that some people eat during daylight and at night, consuming way too many calories. Wealthy people, who eat late dinners also consume much healthier food and are much healthier than the public at large.

    1. glfmamn says:

      They may consume more, but healthier? Calorie is a clalorie student?

  2. Randy says:

    Eat right exercise die anyway.

  3. David says:

    So my question is, do you eat a hearty breakfast when you first get up and then stop eating after 12 hours to follow the plan? If so, this is very similar to present advice saying don’t eat four hours before going to bed. The intermittent fasting part is interesting.

  4. Jake Fontaine says:

    Studies like this are a dime a dozen – they’re the fad diets of science. “We did X to mice and they lived longer, so humans should do that, too.” Questions that should be asked: Why did the mice live longer – what physiological process caused that? Is it related to X? How? Does it even apply to humans? If so, is X the best way to achieve it? Strive for causation, not just correlation.

  5. Dave says:

    This article doesn’t summarize possible reasons for the benefits of eating earlier – only that eating earlier extends lifespans. That’s a problem with many of the studies I read.

    “Experiments found the body clock’s daily rhythms play a big part in the benefits of a healthy diet.”


    “With that in mind, study authors say people should restrict their dining to the most active hours of the day.”


    Is it that when we eat earlier, we’re more active, so our metabolisms are higher and we burn more of those calories vs. storing unburned calories as fat?

    If so, then the “finding” from this study is that physical activity burns more calories. Duh.

    1. David smith says:

      It’s worse that that. This study is about as bad as when the entire scientific community told the nation to stop eating animal fats and start eating Omega 6 fats.
      That literally killed God knows how many 1000’s of people.
      Why did they recommend this? Because 1 scientist said “if fat adheres to arteries, it must come from fat we eat, right”. All they other scientists said “sure” then 40 years later and mountains of dead and they said “oops”.

      1. Paul says:

        And “studies show” that wearing a paper mask will protect you from a virus like Covid.

  6. sri gull says:

    Eating during the day slows me down when I want to be active and productive. I eat a good meal at the end of the day and it sets up relaxation and good sleep. Not sure this study is of any real value but who knows?

  7. Graeme Stewart says:

    I developed Diverticulitis by eating fried foods late at night because of my work, (self-employed, at home since 2012). So I try to move my eating time to 6 or 7 pm. Doesn’t work too well but I manage about 40% of the time.

    However, if I eat late, I retain a lot of the energy absorbed in the gut late, and can bypass breakfast and work right through.
    If I don’t eat at night at all, I will awake deplete of energy and have to eat heartily before I can tackle hard physical work. I’m now 65 and weigh 54Kg or so. Used to be 15Kg more, 20+ years ago, that is.

    Or, be as a soldier. They’d be denied food and the anger drove them onward.

    I did that for years, and I’ve never been a soldier. Message being, we don’t all have choices to make the right decision. I’m trying to help. Don’t eat fried eggs late. Enjoy a hearty, healthy (by your own experience & knowledge) meal at least once every 3-days (yes, really), and sleep plenty.

    The experiment continues. And of course I affirm the conclusions of Mr Takahashi’s team. If you’re lucky enough to have someone living with you, who can cook, whilst you work. Well, it may be frowned upon by the political-correctness squad but those people will live longer, for sure, I think.

  8. Carl says:

    I have been on a fasting schedule stop eating by 9pm and don’t eat until 12pm next day. Have lost 50 lbs over the past year. A1C now below 6.0. Fasting works.

    1. Paul says:

      Excellent, Carl. Good for you!

      Was your weight loss due to the fasting regimen exclusively, or did you change what/how much you consumed?

  9. hulululu says:

    my parents are 87 and 89…they don’t do one thing right for their health. no exercise, eat the worst food i have ever seen and let me repeat they are 87 and 89…meanwhile my friend who was super healthy ate right and climbed mountains die at 62 of pancreatic cancer…moral of the story, do whatever is right for you.

  10. DAVID says:

    To eat only during the day would require people to get up early, before daylight, and go to bed slightly after sunset. Or in other words; early to bed and early to rise, makes a man HEALTHY, wealthy and wise.

  11. Blackhawks Fan says:

    This is all fine, but I’m not a mouse.

    1. David smith says:

      But you are an Original 6 team like my Red Wings.

  12. Sharon says:

    My Dad lived to 103 , perfect health and mind. Ate whatever he wanted, when he wanted. Never did fasting, was never overweight.

  13. David smith says:

    The study is BS. 1 year ago I weighed 260 at 5′ 10″. I was obese and my triglycerides were almost 400. My life after a divorce and move was hectic and I found myself only eating in about a 4 hour window before bed. I eat what I want and as much as I want. Most of it is crap.
    I now weigh 195 and my lab work is stellar.
    I began intermittent fasting without knowing what it was and it is epically effective. There is a reason fasting has been a practice for 1000’s or years.

  14. Keto works says:

    This is what works:
    Eat once or twice in a 4 to 6 hour window and don’t worry about calories as long as you follow this:
    Animal fats are good.
    Meat is good.
    Processed foods are bad.
    Startchy veggies are bad.
    Too many fruits are bad.
    Fruit juice is bad.
    Grains are bad.
    Seed oil is bad.
    Franken foods such as protein bars and a fake hamburger meat is bad.
    Excercise is good but doesn’t make you lose weight.
    Cholesterol isn’t as bad as what your doctor tells you.
    Most medications cause more problems than they help. Fix your problem with your diet first. Statins are stupid and don’t work. u’l Your doctor is probably too old school to know anything about what people should be eating. Stop following the modern standard Amerian diet (SAD) and you will live a longer, healthier life.
    These people are comparing mice that mainly consume grains with what humans eat. Humans were not meant to process grains.

  15. Jim says:

    at 6 ft tall, Ive gone from 212 to 182 with no diet, exercise or magic potions. My first meal is around 5am and I eat nor more after 5 PM. This works well with my early morning schedule. Its not considered intermittent fasting but it works for me.

    P.S. My peak weight was 278lbs. I poo poohd the King,Prince, Pauper diet forever before I finally tried it.

  16. Leethal says:

    You didn’t address something crucial in EVERY diet. What WERE THEY EATING??

  17. Barbaree says:

    Dinner, at home or in a restaurant, is the highlight of the day. How long do you have to live anyway? Whenever I see someone close to or over 100, they always attribute their long life to something like a good cigar every day, or a glass of wine daily, etc. etc. I think it’s because they ENJOY their life that they live longer!