When making dinner reservations, should you be fashionably late or go for the early-bird special?

We spend a lot of time dissecting what we eat, but it turns out the timing of our meals may also be important. And when we choose to eat the very last meal of the day especially may matter, nutritionists say.

"For years, we said a calorie is a calorie no matter when you consume it," dietitian Joy Dubost, a former spokeswoman for the Academy of Nutrition and Dietetics, told the Washington Post. "I don’t know if we can say that anymore, based on the emerging research. The timing of a meal may potentially have an impact."

Studies typically have shown that when calories get consumed later at night, the body tends to store them as fat rather than burn them as energy.

And some studies done with animals found that food is processed by the body in different ways depending on what time of day it's consumed. This might be because of physical activity, hormone levels, changes in body temperature, biochemical reactions and absorption and digestion of food, Steven Shea, director of the Oregon Institute of Occupational Health Sciences at Oregon Health & Science University, told the Washington Post.

Timing matters

man looking in refrigerator When you eat early, you may look for a late-night snack a few hours later. (Photo: Andrey_Popov/Shutterstock)

There's no "best" time to eat dinner across the board, registered dietitian Angel Planells, a spokesman for the Academy of Nutrition and Dietetics, told MNN. It depends on when you get up and go to bed, as well as if and when you eat your other meals.

"Breakfast sets you up for success," Planells said. "If you don't eat breakfast, by lunchtime you're starving, and by dinner any healthy eating plans are out the window."

Typically our dinner schedules are dictated by our lives. If you have young children, for example, you're much more likely to eat early. If you work long hours at your job, you may not be able to get around to eating dinner until much later in the evening.

If late dinners are the case, it's especially key to make smart food choices. Eating heavy meals close to bedtime can lead to heartburn and trouble sleeping.

"Avoid having something too rich or heavy," Planells said. "Your body is going to be trying to process it and you wont be able to go to sleep."

On the flip side, eating too early and choosing certain foods can mean you're hungry just a few hours later.

"If we eat early and don't get enough protein or fiber, the potential downside is we're more likely to get a late-night snack, and choose more decadent foods like cookies, cake or other snacks," Planells said.

Researchers from Okayama University in Japan added further credence to this idea.

They surveyed more than 1,500 residents in the town for several years and discovered eating two hours before bed doesn't affect blood glucose levels. However, the big caveat is that the Japanese diet is high in vegetables, lean protein and small portion sizes. Therefore, eating healthier in general doesn't appear to affect one's weight regardless of how close to bedtime they eat.

Dinner timing and weight loss

A person stands on a digital scale When you eat could have an impact on how much you weigh. (Photo: Jan H Andersen/Shutterstock)

If you're trying to lose weight, you may want to consider eating dinner very early or making a late lunch your last meal of the day.

In a study published in Cell Metabolism, researchers found that meal timing has an impact on human metabolism. They studied a small group of people carrying extra weight and found that those who ate their last meal by mid-afternoon had reduced daily hunger swings and increased fat burning at night.

“Eating only during a much smaller window of time than people are typically used to may help with weight loss, specifically by increasing our body’s ability to burn fat and protein,” said Courtney Peterson, Ph.D., who led the study at Pennington Biomedical Research Center, in a release. “We found that eating between 8 a.m. and 2 p.m. followed by an 18-hour daily fast burned more fat and kept appetite levels more even throughout the day, in comparison to eating between 8 a.m. and 8 p.m. which is average for Americans.”

Eating early also seems to be the optimal time for blood sugar control, Peterson told MNN.

"Starting around 3 p.m., blood sugar control is substantially worse than it is in the morning, meaning that if you ate the same meal at 3 p.m. as you did for breakfast, your blood sugar levels would rise higher, despite the fact that you act the same amount of food," she said.

Peterson's research found that eating in a shorter daily window — 8 hours versus 12 hours — and an earlier time both affect metabolism.

"We and others have found that eating in a short time interval seems to boost fat burning," she said. "In general, based on evidence so far, it’s better to eat dinner earlier in the day or to have breakfast and/or lunch be the largest meals of the day."

Similarly, a 10-week study of "time-restricted feeding" (a form of intermittent fasting) looked at what happens to body fat when people limited their meals to a shorter window of time. Researchers found that people who ate breakfast 90 minutes later than usual and ate dinner 90 minutes earlier than usual lost more than twice as much body fat on average as those in the control group, who ate their meals as they normally would.

"Although this study is small, it has provided us with invaluable insight into how slight alterations to our meal times can have benefits to our bodies. Reduction in body fat lessens our chances of developing obesity and related diseases, so is vital in improving our overall health," said study co-author Jonathan Johnston from the University of Surrey, Chronobiology and Integrative Physiology, in a statement.

"However, as we have seen with these participants, fasting diets are difficult to follow and may not always be compatible with family and social life. We therefore need to make sure they are flexible and conducive to real life, as the potential benefits of such diets are clear to see."

Dinner timing and heart health

When you eat can also have an impact on your heart health. Specifically, women who eat later in the evening are more likely to be at risk for cardiovascular disease than those who eat earlier, according to research presented at the American Heart Association's Scientific Sessions 2019.

Researchers studied 112 women over a year and found that those who ate more of their calories after 6 p.m. had poorer heart health. They were more likely to have higher blood pressure, higher body mass index (BMI) and poorer long-term control of their blood sugar.

"So far, lifestyle approaches to prevent heart disease have focused on what we eat and how much we eat," said lead study author Nour Makarem, Ph.D., an associate research scientist at Columbia University's Vagelos College of Physicians and Surgeons in New York. "These preliminary results indicate that intentional eating that is mindful of the timing and proportion of calories in evening meals may represent a simple, modifiable behavior that can help lower heart disease risk."

When in Rome

tapas set on table in Spain A typical dinner in Spain might include tapas, or small bite-sized dishes. (Photo: zarzamora/Shutterstock)

In many places in Europe, dinner is well past sundown. According to Frommer's, in Spain, "the chic dining hour, even in one-donkey towns, is 10 or 10:30 p.m. (In well-touristed regions and hardworking Catalonia, you can usually dine at 8 p.m., but you still may find yourself alone in the restaurant.) In most middle-class establishments, people dine around 9:30 p.m."

In Europe and other places where they eat late, being overweight is rarely an issue. That's typically because of what they eat, Planells said.

"The amount of food that they eat in the evening is not heavy and rich. Their traditional big meal is light and more like a snack," he said. "If you decide to eat late at night, you don’t want something rich and heavy. You're looking at protein and fiber and making sure you get that so you feel satisfied."

Editor's note: This story was originally published in May 2017 and has been updated with new information.

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.

When is the best time to eat dinner?
Nutritionists say it's not just what we eat, but when we eat dinner that matters.