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Breakfast. It’s the most important meal of the day -- or so we’ve been told.

But science has tackled whether or not this is really true, and the results have been...mixed. One claim you’ve probably heard is that eating breakfast every day helps you lose weight, and there’s definitely evidence to support this. At least, to a degree.

In 2017, the American Heart Association reviewed the science on the effects of different eating patterns, searching databases for relevant studies and looking for big patterns in their findings. And they concluded that people who eat breakfast are less likely to be clinically obese. So there you go!

But... a lot of the studies this was based on just asked people to report their breakfast habits along with various other information about themselves. Without experimental data, there could be lots of other factors at play — like, maybe people who skip breakfast also tend to be less active, or to eat poorer diets overall. When researchers actually do experiments, the benefits of breakfast become less clear.

For example, in 2016, researchers randomly assigned 23 people whose body mass indexes were in the obese range to either eat breakfast or not for 6 weeks. They didn’t standardize exactly what the first group had to eat, but it had to be at least 700 calories before 11AM. Regardless, the researchers didn’t find any difference between the two groups in their weight change during that time.

And other studies have been kind of a mixed bag. So it’s hard to tell if breakfast has a guaranteed effect on weight one way or another, despite what lots of diet websites like to say. But hey, don’t give up on breakfast just yet -- weight loss isn’t the only potential benefit.

That same American Heart Association report found that people who ate breakfast were less likely to have high cholesterol or high blood pressure or problems with their blood sugar. Even that 2016 experiment found that the group assigned to eat breakfast had increased insulin sensitivity at the end of the six weeks -- they needed less insulin in order to regulate their blood sugar, which is a good thing. Right now, why eating breakfast would have these effects isn’t totally clear, but it’s possible that people who skip it end up indulging more later in the day, which can affect their health.

Outside of weight loss and general health, one place where breakfast also gets a lot of emphasis is in schools. School breakfast programs are popular because we hope that they’ll help kids do better academically -- but even for this, the evidence is mixed. A 2009 review of studies of school breakfast programs found that they can have a positive effect on academic performance, but that this may be partly just because they encourage kids to actually show up.

And -- no surprise here -- the benefits of school breakfasts are greater for kids whose overall nutrition is poorer. Another group of researchers took a look at the evidence out there in 2013, and they concluded that habitually eating breakfast did help children stay on task in school and improved academic performance. But again, they cautioned that other factors could be getting mixed up in this, like socio-economic status -- kids who eat breakfast may also come from families that are better able to provide for them overall.

Again, the problem is that a lot of these studies aren’t experimental: They’re just comparing kids who already don’t eat breakfast with those that do. This limits how much they can actually tell us. For example, a 2015 study in Great Britain had 292 kids between the ages of 11 and 13 fill out a questionnaire on their breakfast habits.

And they didn’t find any relationship between kids’ breakfast consumption and their scores on a test of their cognitive reasoning ability. Some actual experiments would help clear this up, but it’s also not a great idea to deprive kids of breakfast if they want to eat it, so for now, we’ll have to work with what we have. Also, if you’re wondering what this all means for adults -- whether breakfast improves our performance at work -- well, sadly, this hasn’t been studied very much.

Unlike schools, adults’ workplaces generally aren’t in the business of feeding them and don’t usually hand out easy-to-interpret test scores, so data is probably harder to come by. So what’s the takeaway here? If you’re the kind of person who eats breakfast, chances are you’re also already someone who has the resources to take good care of yourself and eats well overall.

So just starting your day with a hearty breakfast if you don’t already won’t magically fix everything that’s wrong in your life. But it definitely won’t hurt you, either. And it might even improve your health.

Thanks for watching this episode of SciShow! Nutrition research is complicated, and there’s a lot out there to figure out — like the deal with sugar and fat. Lots of people like to say how horrible one or the other is, but how do they actually affect your health?

You can learn more in our episode all about it. [OUTRO ♪].