• Isaac J. Wedig MS, CSCS

Breakfast: How important is it?

Okay, we’ve all heard it before, breakfast is the most important meal of the day.

Breakfast jump starts your metabolism, keeps you from overeating later on in the day, aids in weight management, and is probably the most fundamental part of a healthy diet.

If there’s one thing that mainstream nutrition has consistently preached over the years, it is the importance of waking up and starting your day with a nutritious breakfast. Unlike eggs, which seem to yo-yo back and forth between magical health food and heart attack in a shell, breakfast is consistently and undoubtedly part of a healthy life and should not be skipped. You’ve heard it from your personal trainer, maybe your doctor, definitely your mom, and perhaps even a dietitian or self-proclaimed ‘nutrition specialist’, like myself.

What does the science say?

With such certainty regarding breakfast there must be an extensive body of unquestionable evidence displaying its benefits, right? Surely the science must support such a strong claim. Funny enough, this isn’t the case at all.

Fairly consistently, the literature displays an association between eating breakfast and decreased overall appetite, decreased overall food intake, decreased bodyweight, and improved blood sugar control. However, these associations are not only weak, but most importantly, are only associations. As any intelligent researcher will tell you, correlation does not equal causation. With only correlational data, we can’t definitively say that eating breakfast is the direct cause for these outcomes. In order to highlight the importance of breakfast, we have to demonstrate a direct mechanism by which it is causing the associated effects. There are many other lifestyle and dietary variables that go hand-in-hand with habitual breakfast eating. It could be any number of alternative variables effecting weight management, appetite, food intake, and blood sugar.

To cloudy the water even more, there is some research that suggests that skipping breakfast might actually provide several health benefits, including increased fat breakdown, improved blood sugar control, improved cardiovascular function, and deceased total food intake. These claims are again fairly limited, coming from animal studies and weak correlational data.

As you can see, things aren’t as cut and dry as our conventional wisdom would lead us to believe. In fact, if you take a look at the complete body of available research, we don’t actually have any unequivocal evidence demonstrating that eating breakfast provides any direct benefits when other factors of the diet such as calorie and macronutrient intake are controlled. “Breakfast is the most important meal of the day” appears to be more of a socially reinforced notion than a real science-based concept. With that said, let’s take a deeper look at some of the typical claims made for breakfast. Breakfast is promoted as effecting metabolism and hunger levels, both of which are very likely mechanism by which breakfast could be promoting the positive health outcomes that we see in correlational data. But lets take a look!

Does breakfast increase your metabolism?

This is probably the most common claim made by the breakfast advocates. Seems like a decent theory, eating first thing in the morning gets your metabolism going, right?

Yes, it certainly does, but not in the way that most people think. Anytime that we consume a meal, our metabolism increases to a small degree. Following the ingestion of food, the body is left responsible for dealing with it. Digesting and processing food is energy demanding and therefore effectively increases our rate of energy expenditure above our normal resting rate. However, this increase in energy expenditure is only short-lived, once the food is digested, processes, and stored, energy expenditure returns to normal. This effect of food consumption on metabolism is referred to as the thermic effect of food (TEF).

It makes sense to say that eating breakfast increases your metabolic rate temporarily. But what about for the rest of the day? In order for breakfast to truly effect weight management and overall metabolic rate, we have to ask whether or not it increases 24-hour energy expenditure, or more importantly, whether it impacts net 24-hour energy balance. Weight loss, after all, is dependent upon daily energy balance, not just any one snap shot of energy balance or metabolic rate at one given time of day.

Let’s assume that we equate total calorie and macronutrient intake for two people over a 24-hour period. The only difference is that one person eats breakfast and the other does not. They both consume the same amount of total food during the day and therefore digest, process, and store the same amount. Thus, the two individuals will expend the same amount of energy due to TEF, regardless of whether they ate breakfast or not. This logically demonstrated that eating breakfast doesn’t increase 24-hour daily energy expenditure and therefore won’t alter energy balance or weight loss.

It’s been demonstrated time and time again that meal number, meal distribution, and meal timing, do not affect 24-hour energy expenditure when calories are equated.

Therefore, we can conclude that breakfast does not “jump start” or increase your metabolism like Steve from Planet Fitness said. There’s some modest speculation that breakfast might facilitate greater daily energy expenditures through an increase in non-conscious physical activity, or non-exercise activity thermogenesis (NEAT), however this has not been demonstrated clearly and is most likely too small of an effect to promote any significant differences for weight management. Sorry Steve, but weight loss is a little more complicated than waking up to a bowl of oatmeal and some over easy eggs.

Does skipping breakfast lead to overeating later on in the day?

Okay, so breakfast doesn’t increase daily energy expenditure, it doesn’t boost your metabolism, turn you into a calorie burning super-human, or give you the ability to shoot laser beems out of your eyes.

Let’s not give up on breakfast just yet. The energy balance equation has two sides; energy expenditure and energy intake. In other words, energy balance equals ‘calories in’ versus ‘calories out’. This dictates bodyweight change. Eating breakfast may not affect energy expenditure but does it affect daily calorie intake? If you eat breakfast does it lead to deceased appetite and thus lower 24-hour energy intakes?

If you skip breakfast you will overeat later on in the day, leading to weight gain and the onset of numerous health problems. This is the second biggest claim made by the breakfast advocates. In the name of science, everyone’s favorite cereal company, Kellogg’s, funded a study to test the theory. The study included two groups, one that was fed a 600-calorie breakfast and another that skipped breakfast entirely. For lunch, both groups were taken to an all you can eat buffet where their food intakes were objectively measured by weighing. They found that the individuals who skipped breakfast ate 15% more than those who ate breakfast. The average intake at lunch was about 1,000 calories in the breakfast group compared to about 1,150 calories in the no breakfast group. The study concluded that if you skip breakfast, you are more likely to overeat at lunch. However, if you look at the overall calorie balance in the groups between breakfast and lunch together, the group that ate breakfast actually consumed more total calories on average. The breakfast group consumed around 1,600 calories whereas the no breakfast group consumed 1,150 calories.

This demonstrates that eating breakfast may actually increase energy intake during the day! Strike two for breakfast. The problem with this study is that it did not look at total daily food intake, only breakfast and lunch. It’s possible that the breakfast skipping group may have also compensated by overeating during the other meals of the day beyond lunch, possibly leading to an equal or even greater energy intake than the breakfast group.

Practically speaking, if an individual doesn’t typically eat breakfast and they decide to start doing so because Steve from Planet Fitness said they have to, then they are effectively adding calories to their diet. Increasing your caloric intake seems a bit counter-productive if your goal is weight loss, doesn’t it? At this point, what is the benefit of adding breakfast?


Don’t misinterpret this article. I am not by any means suggesting that you should skip breakfast. The practical take home message is this;

If you don’t like eating breakfast, then don’t eat it.

If you don’t wake up hungry, if you don’t enjoy eating first thing in the morning, or your stomach gets upset when you do, then don’t force food down! As important as society makes breakfast sound, it really doesn’t appear to have much of an effect at all on health and weight management. What does have a profound impact is your 24-hour calorie balance. Focus your efforts on the big picture and don’t get lost in the details that make little to no difference.

Forcing breakfast can actually increase your caloric intake and possibly push you into a calorie surplus. This is not a good thing if you’re trying to manage your weight and stay healthy. Additionally, forcing yourself to eat when you really don’t want to is no fun. The most successful diet is the one that you can most easily integrate into a lifestyle. If your lifestyle doesn’t include breakfast, that’s perfectly okay. Don’t change your life to fit a diet, change your diet to fit your life. Be flexible with your meal timing and adopt a meal distribution that is best for you. At the end of the day, it doesn’t matter! So do what you enjoy and do what you can adhere to!


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