The idea that we should eat three meals a day is surprisingly modern. How many meals a day is best for our health?
It is highly likely that you eat three meals a day - modern life is organized around this way of eating.
We're told breakfast is the most important meal of the day, we get lunch breaks at work, and then our social and family lives revolve around evening meals.
But is it the healthiest way to eat?
Before considering how often we should eat, scientists urge us to consider when we shouldn't.
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So-called "intermittent fasting," when you limit your food intake to an eight-hour window, is becoming an increasingly frequent subject of research.
Allowing our bodies to go at least 12 hours without food allows our digestive system to rest, says Emily Manugan, a clinical researcher at the Salk Institute for Biological Studies in California, and an author of the study. "When to eat" from 2019.
Rosalyn Anderson, an associate professor at the University of Wisconsin School of Medicine, studies the benefits of calorie restriction, which is associated with a lower level of inflammatory processes in the body.
"When you have fasting periods every day, you can get exactly those benefits," she says.
"It builds on the idea that starvation puts your body in a different state, where it's more ready to repair itself and look for damage, and to clear itself of misfolded proteins."
Misfolded proteins are defective versions of normal proteins, molecules that perform a wide range of important tasks in the body.
Misfolded proteins are are associated with a large number of diseases.
Intermittent fasting is more in line with how our bodies evolved, Anderson claims.
She says this gives the body the rest it needs to store food and send energy to where it's needed, as well as start the mechanism for releasing energy from storage in our body.
Fasting could also improve our glycemic response, when our blood sugar spikes after a meal, says Antonio Paoli, professor of exercise and sports science at the University of Padua in Italy.
When you have less spikes in blood sugar, it allows you to store less fat in your body, he says.
"Our data suggests that eating an early dinner and extending your fasting time frame increases positive effects on the body, such as better glycemic control," says Paoli.
It's better for all cells to have lower levels of sugar in them because of a process called glycation, Paoli adds.
Then glucose binds to proteins and compounds called "advanced glycation end products" are formed, which can cause inflammation in the body and increase the risk of getting diabetes and heart disease.
But if intermittent fasting is a healthy way of eating - how many meals does that leave room for?
Some experts argue that one meal a day is best, including David Levicki, a professor at the College of Human Ecology at Cornell University in New York, who practices it himself.
"There's a lot of data showing that if I show you food or pictures of food, you're more likely to eat, and the more often the food is in front of you, the more you'll eat that day," he says.
That's because, before we had refrigerators and supermarkets, we only ate when food was available.
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Throughout history, we have eaten one meal a day, such as The ancient Romans, who ate one meal around noon, says food historian Seren Charrington-Hollins.
Wouldn't one meal a day leave us hungry?
Not necessarily, claims Levicki, because hunger is often a psychological sensation.
“When the clock strikes noon, we may get the urge to eat or you may be conditioned to eat breakfast every morning, but that is nonsense.
"The data suggests that if you don't eat breakfast, you'll eat fewer calories overall throughout the day."
"Our physiology is built for feasting and fasting," he says.
However, Levicki does not recommend this approach for people with diabetes.
But Manugan doesn't recommend eating one meal a day, as that can raise our blood glucose levels when we're not eating - known as fasting blood glucose.
Elevated fasting blood glucose over a long period of time is a risk factor for type 2 diabetes.
To keep your blood sugar low, you have to eat more regularly than once a day, Manugan says, because that prevents the body from thinking it's starving and starting to release more glucose when you end up eating something in response.
Instead, she says, two to three meals a day are best—with most of the calories consumed earlier in the day.
This is because nutrition late at night is associated with cardio-metabolic diseases, such as diabetes and heart disease.
"If you eat more of your food earlier, your body can use that energy you put into it through food throughout the day, instead of it being stored in your system as fat," says Manugan.
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But eating too early in the morning should also be avoided, she says, because then it won't give you enough time to starve.
Also, eating too soon after waking up works against our circadian rhythm - known as our body clock - which scientists say dictates how our body processes food differently throughout the day.
Our bodies release melatonin during the night to help us sleep - but melatonin also stops the production of insulin, which stores glucose in the body.
Because melatonin is released while we sleep, the body uses it to make sure we don't take in too much glucose while we sleep and eat, says Manugan.
“If you eat calories while your melatonin is high, you get very high glucose levels.
"Ingesting a lot of calories at night is a big challenge for the body, because if insulin is suppressed, your body can't properly store glucose."
And, as we know, high glucose levels over long periods of time can increase the risk of developing type 2 diabetes.
That doesn't mean we should skip breakfast entirely, but some evidence suggests that we should wait an hour or two after waking up before cracking the eggs.
Also, it's worth remembering that breakfast as we know and love it today is a relatively new concept.
"The ancient Greeks were the first to introduce the concept of breakfast, they would eat bread dipped in wine, then have a modest lunch and then a hearty evening meal," says Charrington-Hollins.
At first, breakfast was reserved for the aristocratic class, says Charrington-Hollis.
It was first received in the 17th century, when it became a luxury for those who could afford food and time for a relaxed meal in the morning.
"Today's concept of breakfast as the norm arose during the Industrial Revolution in the 19th century and the introduction of working hours," says Charrington-Hollins.
Such a routine leads to three meals a day.
"The first meal would be something fairly simple for the working class - it could be street food from a stall or bread."
But after the war, when the availability of food decreased, the idea of eating a full breakfast was not possible and many people started skipping it.
"The idea of three meals a day was thrown out," says Charrington-Hollins.
"In the XNUMXs, breakfast became what we know today: cereal and toast.
"Before that we were happy if we ate a piece of bread spread with jam."
So science seems to want to tell us that the healthiest way to eat during the day is to have two or three meals, with a long fasting window during the night, not to eat too early or too late in the day, and to consume more calories earlier in the day.
But is it realistic?
Manugan says it's best not to specify the best times to eat, as this can be difficult for people with duties and responsibilities, such as those who work night shifts.
"Telling people to stop eating after seven in the evening is not helpful because people have different schedules.
"If you try to give your body regular nights of fasting, try not to eat too late or too early, and try not to eat large last meals, this can usually help.
"People can practice at least some of this," she says.
"You will experience dramatic changes only if you delay the first meal a little and if you eat the last one a little earlier. If it becomes a habit and you haven't applied anything else, it can leave a big mark."
But whatever changes you make, scientists agree that consistency is key.
"The body works in patterns," says Anderson.
"We react to the anticipation that we will be fed. One thing intermittent fasting does is to impose a pattern, and our biological systems like patterns."
She says that the body registers cues to participate in our eating habits in order to best cope with the food when we eat it.
When it comes to the number of meals we consider normal, Charrington-Hollins sees changes on the horizon.
"Over the centuries, we were conditioned by three meals a day, but that is now starting to be questioned and people's attitude towards food is changing.
"Our lifestyles have become more sedentary, we no longer do the levels of physical work we did in the 19th century, so we need fewer calories.
"I think in the long run we'll start going back to the light meal, then the main meal, depending on what's going on at work." Our opening hours will be the main driver of this.
"When we got over the post-war hardships, we accepted three meals a day because suddenly there was plenty of food.
"But time moves on - food is everywhere now."
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