What Is The Healthiest Time To Eat Dinner?

Getting dinner on the table before 7 p.m. can feel like the work week’s greatest challenge, but there’s a lot of evidence to suggest that making an attempt to dial back your evening mealtime by an hour or two is better for you in the long run—and may lead to a reduced risk of developing metabolic diseases such as obesity and diabetes.

That’s because many experts believe that eating earlier in the evening falls in line with our circadian rhythms.

"Circadian rhythms are daily rhythms," says Phillip Karpowicz, a professor in the department of biomedical sciences at the University of Windsor and head of of the Karpowicz Lab, which studies the influence of circadian rhythms on intestinal health and disease.

These rhythms are most commonly understood as influencing our sleep-wake cycles, but there's more going on in our bodies than that, explains Karpowicz. This natural 24-hour clock affects everything from body temperature to how our body processes the nutrients we eat.

"There's literally a system of genes that are found inside pretty much all the cells of your body that keep track of 24-hour time, just like a clock on the wall keeps track of time," he adds.

How our body processes food during certain periods of day also follows this internal timer, and the time at which you choose to eat dinner can work with the internal rhythms of your organs—or against them, says Karpowicz.

"Those tissues are really responsive to feeding time," he explains. "They're going to respond to the hormones that you release when you eat nutrients, like insulin and glycogen."

When you set mealtimes in sync with those natural processes, then everything "works really well, and you end up being more healthy as a result," says Karpowicz. He explains that a 12-hour window in which you eat breakfast around 6 or 7 a.m., and consume your last meal of the day about 12 hours later, is best.

Eating With Your Body's Clock In Mind

This way of thinking about eating meals to match the body’s internal rhythms is sometimes known as “chrononutrition.”  A recent deep dive on the topic by journalist David Cox for The Telegraph notes that the concept is so popular in Japan that some convenience store foods are even labelled with optimal consumption times. (Cox notes that Japanese researchers encourage people to eat more protein for breakfast and less protein in the evening because muscle synthesis—which uses the nutrient to grow new muscle fibres—is "more active earlier in the day.")

The link between an increased risk of obesity and meal times isn't related to calorie consumption, Karpowicz says. It's mostly just because eating late at night contradicts what your body is programmed to do at night, which is wind down and go to sleep.

But What If You’re A Shift Worker?

Shift workers are most prone to experiencing the dislocating effects of having to eat and sleep out of sync with these natural body rhythms, says Karpowicz. Many have increased risk of metabolic conditions as a result.

If you are a shift worker, however, he thinks you should be aware of how this "scrambled" approach to your internal rhythms does affect the way you feel, and even your body composition, and plan ahead. That means doing the best you can to eat within a 12-hour window, and trying to keep to a regular schedule that doesn't dramatically shift every couple of days, or weekly.

Don't lament if you can do it all the time, he says—even aiming to do it as much as you can is good.

Ultimately, If you try to work with your internal rhythms rather than against them, your body will work better and you'll likely feel better, too. But if you can't do it all the time, it's "not an injury" that results in irrevocable damage. It can be a goal to work toward, says Karpowicz. "It's about a lifestyle."