You’ve probably heard the mantra that breakfast is the most important meal of the day. It’s been ingrained into society from nutrition experts, the food industry and even our parents. And it might make sense. For most of us, we wake up after not eating for at least 12 hours. So breakfast, essentially, breaks our fast. But is it really the most important meal of the day?

When it comes to eating breakfast, there’s a wide range of eating patterns. While only a third of adults in the US eat breakfast everyday, it’s nearly double that in Canada. And many people who miss breakfast report wishing they ate it daily. This leaves about 10% to 20% who never eat breakfast, making it the most missed meal of the day.

For me, I’m a breakfast person. I usually eat something within two hours of waking in the morning. As a kid, I would get up grab the box of Corn Flakes or Cheerios, pour it in a bowl, add milk along with sugar, and without much fuss, have my breakfast. While it satisfied my hunger at the time, there was probably as much nutrition in the cardboard box the cereal came in than the cereal itself.

With diet patterns such as time-restricted fasting and intermittent fasting becoming popular, the notion of skipping breakfast may be increasing. But which side of the health fence does breakfast come down on?

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Does Breakfast Make You Smarter?

For decades, cereal companies have promoted breakfast as an essential part of the day. There were numerous TV commercials saying kids who start their day off with breakfast did better in school. And research suggests this may be the case as school performance is lower in both children and teens who skip breakfast.

However, it’s unclear whether the lower performance is due to skipping breakfast or not. The children who missed breakfast also tended to be more economically deprived. And unlike adults who skip breakfast, these children didn’t make up the required nutrition later in the day, potentially putting them into a malnourished state. Supporting this, is evidence that a higher-quality breakfast (more diverse food groups) has been associated with better performance. Given the crucial brain development that occurs in children, it’s possible missing breakfast may actually have implications on development.

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Skipping Breakfast Might Make You Hangry

If you’re like me, going more than a few hours after waking without eating makes you hangry. This is most likely due to a lack of blood sugar circulating. And you may not be alone. A study of 66 adults reported those who skipped breakfast reported lower sleep quality and worse mood upon waking. Although this doesn’t mean we’re going to starve. Most of us have plenty of energy stores to get us through the morning without eating.

But it may be more than just one’s morning mood that’s affected. People who delayed or skipped breakfast were more likely to have a mood disorder. A separate study found skipping breakfast was associated with greater chances of having depression. However, neither of these studies were conclusive and it’s just as likely that having a mood disorder can affect one’s eating habits.

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Does skipping breakfast lead to weight loss?

The debate for breakfast is most fierce when it comes to weight loss. Breakfast skippers say they eat less calories, and those eating breakfast maintaining they eat less throughout the day. Much of the early data comes from the National Weight Loss Registry in the US. The registry is a volunteer database of people who have lost weight with the aim to understand the successes of weight loss. In 2002 it reported that nearly 80% of the 3000 members ate breakfast regularly. The news spread like wildfire; breakfast was essential to weight loss.

Over the years, the notion breakfast was essential for weight loss grew. An observational study of over 50 000 people reported those who ate breakfast and had the largest meal of the day in the morning, were better able to maintain their weight. It wasn’t until much later randomized studies emerged. These generally found no difference in short-term weight loss between people eating breakfast compared to skipping breakfast. For breakfast skippers, this may be due to making up the missing morning calories later in the day. However, these studies ranged from one week to four months, so the effect on long-term weight loss isn’t clear.

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Breakfast, Part of Healthy Living

Now weight loss isn’t the end all and be all (nor should it be). There are other potential health consequences to keep tabs on. A cross-sectional study found that breakfast skippers have a 2.5 fold greater risk for atherosclerosis compared to non-skippers. And a comprehensive review of long-term studies noted a 21% increase risk for diabetes with breakfast skipping.

It’s possible eating breakfast could just be a marker for other healthy habits (people who eat breakfast tend to be more health conscious) and breakfast itself could have nothing to do with long-term health. However, a number of well-conducted short-term studies indicate skipping breakfast can adversely affect blood sugar metabolism, which may be at the root of the higher risk for diabetes.

The Effects on Your Internal Clock

The circadian rhythm is basically your body’s internal clock. We commonly know this as the sleep/wake cycle and how our body responds to the light and darkness of the day. Your circadian rhythm is also connected with hunger and eating through a number of hormones.

But it also may be that when you eat influences your internal clock. For example, eating late at night can disrupt this rhythm and result in elevated blood sugar levels throughout the night. In breakfast eaters, after six days of delaying breakfast, the rise in morning body temperature was delayed. And skipping breakfast also altered expression of genes related to the internal clock, as well as disturbed glucose metabolism.

The long-term implications of these changes are unknown. However, there is a growing trend to follow a circadian diet, restricting food intake to daytime hours. This pattern of eating is quite similar time-restricted eating. In contrast, some scientists suggest that people used to skipping breakfast may have altered they circadian rhythm to a point that it works for them. And a change from what the body is used to may result in short-term metabolic disturbances.

While it’s unclear if breakfast is more important than any other meal, having breakfast may be better than not having it. That being said, just as with any meal, it’s the quality of meal that also matters. My early breakfasts of cardboard-like cereal were likely far down on the quality scale. A breakfast that includes a good source of protein (eggs, peanut butter, yoghurt), fat (avocados) and fruit is a much better way to start the day.

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This post was originally published on April 18, 2018 and updated on March 24, 2021.