Study: Eating at night could shorten your life

By Mark Waghorn via SWNS

Eating during the day instead of at nighttime could add years to your life, according to new research from the University of Texas (UT).

It's not just what you consume.

Cutting down on fatty and sugary foods and having meals at the right time increased longevity in mice by a third.

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. Humans are lively in the day - or diurnal.

Dining should be restricted to daytime hours.

In lab animals tracked over four years, a reduced-calorie diet alone extended survival by ten percent.

But the improvement increased by 35 percent 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, of the University of Texas, said: "For people, an analogous plan would restrict eating to daytime hours."

Eating less is known to boost health. Studies in a variety of animals have shown it can lead to a longer, healthier life.

The latest findings add to evidence having a hearty breakfast or lunch instead of dinner is also key - at least for humans.

Prof Takahishi, a molecular biologist, said: "The research helps disentangle the controversy around diet plans that emphasize eating only at certain times of day.

"Such plans may not speed weight loss in humans, as a recent study in the New England Journal of Medicine reported, but they could prompt health benefits that add up to a longer lifespan."

Recent years have seen the rise of many popular diet plans that focus on what’s known as intermittent fasting.

They include fasting on alternate days or eating only during a period of six to eight hours per day.

Now Prof Takahishi and colleagues have unravelled the effects of calories, fasting and daily, or circadian, rhythms on longevity.

They housed hundreds of mice with automated feeders to control when and how much each individual ate for its entire lifespan.

Some could gorge as much as they wanted while others had calories restricted by 30 to 40 percent. The latter 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 that time-restricted eating has positive effects on the body even if it doesn’t promote weight loss.

The study found no differences in body weight among mice on different eating schedules. Prof Takahishi said: "However, we found profound differences in lifespan."

He hopes 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 those diets’ effects.

Meanwhile, Prof Takahashi is taking a lesson from his mice ­- he restricts his own eating to a 12-hour period.

But he added: "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 described the paper in Science as "a very elegant demonstration."

He said: "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, Boston, who was also not involved in the work, said it highlights the crucial role of metabolism in aging.

She said: "This is a very promising and landmark study."

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.

But it has 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. 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, said Dr. Das.

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.