How does when you eat affect your health?

Editor’s note: As we enter 2023, we’re running a series of stories in Star Culture on diet and nutrition, navigating eating healthier amid rising food costs and advice on making sustainable choices.

Long before intermittent fasting became a thing, a lot of theories have existed about the best time to eat.

Should we skip breakfast? Or is it the most important meal of the day? Is it safe to eat supper after the sun goes down? Or should we take a page out of the snowbirds’ books and take advantage of the Early Bird Special?

Does an “eating window” make sense? In October, a study published in the journal Cell Metabolism found that research subjects who limited their eating to a 10-hour window every day had lower blood pressure and blood sugars at the end of 12 weeks.

A month later though, research in the Journal of the Academy of Nutrition and Dietetics seemed to complicate the story when it found a correlation between skipping meals or eating them too closely together and all-cause mortality (death from any cause).

We can be forgiven for being a little confused about what’s what.

“I’ve always been a little skeptical about the idea of breakfast being such an important thing,” said Rebecca Christensen, CIHR post-doctoral fellow in the kinesiology department at the University of Toronto, who researches diets in the intermittent fasting family. “Especially when we see that, in a lot of studies for time-restricted eating, people start eating around 10 or 11 in the morning and we see health benefits.”

Christensen notes that many intermittent fasting plans are more restrictive than the time-restricted eating that her research is focused on.

“That said, generally speaking, the weight loss that occurs with time-restricted eating is what we would define as a modest weight loss,” she adds. “Not like the levels that you would see with something like bariatric surgery, but we still see meaningful weight loss, around 10 pounds and sometimes even up to 20 pounds.”

It’s not clear why people lose weight in this way. Some have suggested that the reason it can work is that people simply don’t have time to eat as much and skip meals. One study published in 2021 found that people failed to lose a meaningful amount of weight when they could eat absolutely anything they wanted in an eight-hour window.

And, when it comes to breakfast, what you eat might be more important than when.

“Having a higher protein meal, especially the first meal of the day, breakfast, is a really important strategy to start off with,” explained Sana Motlekar, a registered dietitian in Toronto. “It will help stabilize your blood sugars and prevent you from having cravings even much later in the day.”

Researchers have long connected eating protein, which makes us feel full, to a drop in production of the “hunger hormone” ghrelin, which increases our appetite.

“People always think there’s so much to do when they try to change the way they eat and ask ‘Where should I start?” Motlekar said. “Well, protein at breakfast is a great place to start.”

A massive new study supports that philosophy, since the authors found that people who skimped on protein at breakfast had a higher caloric intake for the rest of the day and ate more highly processed foods on top of it all.

And what about dinner? We’ve all heard the advice that we should cut out the late-night snacking and eat dinner at an earlier hour. Some even suggest strict cut-off times, as in, no food after a certain hour. Seven at night is common, but we’ve heard earlier.

“It really depends on the individual, but we do know that people who eat later in the day tend to eat things that are more calorically rich,” said Christensen. “Especially nighttime snack foods, which don’t tend to be salads.”

“But it also goes back to the circadian rhythm,” she added. “The idea is that the closer to bed you are your body has less time to expel the glucose. When you’re lying down, your body isn’t really working the same way to get rid of the glucose, so that will mean higher levels over the night which will then contribute to your overall levels throughout the following day being higher.”

Christensen said they advise people finish eating at least three hours before bed to allow the body to do its work on the glucose. There’s no specific magic cut-off hour like feeding gremlins after midnight. It all depends on when you go to bed.

So, try to get some protein into your mouth early in the day, whenever that might be for you. And give yourself a few hours between dinner and bed. No snacking.

That seems to be what we know for sure — for now, at least.

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