The Shocking Importance of What You Eat For Breakfast

Just how important is breakfast?

That was the question on researchers minds as they were conducting various studies on self-control. We have been told over and over again just how important breakfast is for our health and energy. But could it benefit our willpower as well?

In order to find the answer, they went to one of the most important real-world laboratories out there – a high school. 

The Experiment

Researchers separated students into 3 groups. The first group was to eat a healthy breakfast of low-glycemic foods (such as eggs, oatmeal and fruit), the second group was given a breakfast of high-glycemic foods (like muffins and donuts) and the third group was to go without breakfast at all. [1]

The teachers of the high school were not aware which students were in each group and were instructed to rate each on their behavior and academic performance during the morning periods from 8:00-10:30am.  

At 10:30am students from all 3 groups would be given the same healthy snack. The teachers would then grade each of the students on the same measures of behavior and academic performance for the hours of 10:30am-1:00pm.

The Results

Across the board, students with the healthy breakfast greatly outperformed the others on the measures of behavior and performance in the 8:00-10:30am time slot.  

The students who ate the high-glycemic breakfast were graded well at the beginning of the morning, but as it got closer to 10:30, they started to act out and lose their focus.

The students who ate no breakfast at all performed the worst on both measures. They were more undisciplined and unmotivated – regardless of their academic history, race or socioeconomic status. [1

This may not come as a shock to you. After all, this proves what we’ve been told for years – breakfast really is important! However, the truly interesting finding comes from the time period after each student ate a healthy snack. After the snack, all of the differences in behavior and performance between the 3 groups vanished. They all averaged out to roughly the exact same scores!

What Happened?

So what can we learn from this study? Clearly breakfast is important, but many of us use the importance of breakfast as an excuse to eat whatever we want. Pop Tarts and Toaster Strudels may be better than nothing, but this study indicates that they won’t last. Then regardless of whether or not you eat breakfast, if you give yourself a healthy snack you will be more focused and energized afterward.

So merely having breakfast is not the important thing, it’s what you eat for breakfast. What you eat has a profound effect on your willpower. To exert willpower, the brain uses a specific energy source produced by the body called glucose. Glucose is produced in the bloodstream from the digestion of foods. 

High-glycemic foods (sugar, muffins, Pop Tarts) will produce a spike of glucose in your body followed by a subsequent crash. This will give you a quick willpower boost, but it won't last. This is why the students with the unhealthy breakfast performed well for about an hour, then performed just as poorly as those without breakfast.

Low-glycemic foods (lean protein, fruit, vegetables) will produce a consistent flow of glucose into the body which will give you long-term, sustainable willpower. This is why the students with the healthy breakfast were able to perform well for the full first period, and why all 3 groups performed well afterward.

This finding may sound obvious, but the implications may be even greater than you think. 

The Shocking Importance of Glucose

Not all people are as good at producing glucose efficiently in their blood stream as others. Diabetics and people with hypoglycemia, for example, have a harder time maintaining a consistent flow of glucose than others. This means if they are not able to treat the lack of glucose in their system through medication, they can run into some serious problems. 

How serious? Researchers who were conducting studies on the importance of glucose tested the seriousness of these afflictions in those who lost a big sense of self-control – criminals.  

Here are some of their findings [2]:  

Below average glucose levels were found in 90% of juvenile delinquents!

Those with hypoglycemia were more likely to be convicted of traffic violations, public profanity, shoplifting, exhibitionism, public masturbation, embezzlement, arson, spouse abuse, child abuse, and destruction of property.

To test the effects even further, researchers measured the glucose levels of prisoners who were released, then tracked whether or not they committed another crime. With this information, they could predict with over 80% accuracy who would commit another crime – regardless of prior convictions, family issues, race or socioeconomic status!

What This Means for Us

Clearly, glucose plays a remarkably important role in our ability to control our behavior. To give yourself a consistent stream of healthy glucose to fuel your willpower, stick to low-glycemic foods.

These include:


Nothing fancy is required – just lean cuts of beef, poultry, pork, fish and free-range eggs.


Specifically those nuts that are high in omega-3 fatty acids like walnuts, pecans and cashews. (Note: this does not include legumes like peanuts).


Fresh fruit is preferred over dried fruit because dried fruits have a high concentration of sugar in them. This will result in the glucose spike for the short term and lead to a subsequent crash. Some good choices are bananas, blueberries, apples and cherries.


All vegetables will help build your long-term willpower, but specific veggies that pack a willpower punch are root-based. These include sweet potatoes, carrots, and onions which will all give you some serious willpower fuel!

The Importance of Breakfast

This article began by examining the importance of breakfast, so that is where we will close. Before you try to set a plan to completely overhaul your diet to some of the foods listed above, stop! 

If you do not currently have one of the 4 food types listed above on a regular basis, do not try to have them for all 3 meals – just have them consistently for breakfast.

There are 3 reasons you should consistently eat a low-glycemic breakfast:


If you’re going to eat one meal where you produce a consistent stream of glucose, it may as well be the first one. This will give you more time throughout the day in which your brain has consistent glucose to work with, as opposed to dinner in which you will only have a few hours before bed.


With the increased level of glucose in your system, you will have more willpower to resist the donuts that were brought into the office and order the healthiest item on the lunch menu. By eating a healthy breakfast, you’re setting yourself up for a healthy snack and lunch as well.


Your willpower is strongest in the morning – provided that you had a good night’s sleep. This means that it will be easier for you to work up the willpower to cook a healthy meal than, say, after a long day at work. So eat healthy when it’s the most important and easiest time of the day. [3]


We have been told throughout our lives how important a healthy breakfast is. What this study showed is just how important what you eat for breakfast is. Although eating a donut or a muffin will be better than eating nothing, it will leave you with a depletion of willpower by the middle of the morning.

To avoid this, focus on eating a healthy breakfast every morning. Doing so will give a consistent stream of willpower fuel to use throughout the day. This extra willpower will give you more energy to focus, be productive, and resist cravings. By eating a healthy breakfast, you are setting yourself up for an extremely successful day! 


  1. Gailliot, M., & Baumeister, R. (2007). The Physiology Of Willpower: Linking Blood Glucose To Self-Control. Personality and Social Psychology Review, 303-327.

  2. Baumeister, R. & Tierneym J.(2011) Willpower: Rediscovering the Greatest Human Strength. New York: Penguin, .

  3. Spiegel, K., Tasali, E., Leproult, R., & Van Cauter, E. (2009). Effects Of Poor And Short Sleep On Glucose Metabolism And Obesity Risk. Nature Reviews Endocrinology, 253-261.