MIT: Department of Athletics, Physical Education, and Recreation
The Influences of Nutrition on Productivity:
How Eating a Healthy Diet Can Impact Your Brain Function, Energy Levels, and Your Mood
The benefits of eating a healthy diet we already know:
 A healthy and balanced diet will help you manage and maintain a healthy weight, reduce the risk of heart
disease and stroke, protect against certain cancers, lower blood pressure, and lower cholesterol.
 A diet rich in healthy, nutrient dense, foods is essential for the development and maintenance of your bones,
muscles, and brain.
o Nutrient dense food: foods that contain high quantities of vitamins and minerals while supplying
lower quantities of calories, e.g., fruits and vegetables. More nutrition bang for your calorie buck!
o The opposite of nutrient dense food is empty calorie food: foods that provide very few micronutrients
but supply high amounts of calories, e.g., potato chips, baked goods, candy, soda, etc.
How does eating a healthy diet affect my energy levels and my mood?
 The foods you choose to eat influence both your energy levels and your mood.
 Eating heavy foods will generally leave you feeling tired and sluggish.
o Heavy foods include fried foods, foods with high percentage of calories from fat, foods with a lot of
added sugar, large quantities of food at once, and empty calorie foods.
 An insufficient intake of calories and nutrients will leave you feeling fatigued and cranky.
 When you eat every four or five hours, your blood sugar levels will be more stable and you will be less likely
to experience dips. When your blood sugar gets low, you can feel fatigued and irritable, and be quick to snap
at others.
 Eating regular, light, balanced meals rich in fruits and vegetables, whole grains, and lean proteins will leave
you feeling energized, upbeat, and ready to concentrate throughout your day.
What role does sugar play?
 Eating a meal that contains carbohydrates raises your blood sugar levels.
o As you break down and digest carbohydrates, glucose is released into the blood stream. In response to
the presence of glucoses, your body releases insulin. Insulin signals the body’s cells to absorb the
glucose and store it as energy for later use.
 This process is quickened when the meal is made up mainly of simple carbohydrates (e.g., sugary drinks,
candy, white bread, white rice, etc.). When a meal is only made up of simple carbohydrates, glucose will
enter the blood stream faster. Insulin will then be released more readily, and as a result your blood glucose
levels will fall faster than they would had you eaten a meal with complex carbohydrates (e.g., oatmeal, lentils,
pasta, barley, etc.), fat, and/or protein.
 The crash after a meal made up of simple carbohydrates can make your body think it is hungry for more sugar
even though you just ate; it makes it difficult to read your body’s signals.
 The digestion of carbohydrates also stimulates the release of serotonin and beta-endorphins* in the brain; both
serotonin and beta-endorphins engender positive feelings, but when they are released as a result of a sugar
spike, they will be short lived.
o When the brain releases serotonin and beta-endorphins after digesting carbohydrates, the body
metabolizes them faster than usual. This means you will feel a spike in “happy” feelings as they are
released, followed by a crash as they are digested. This leaves you feeling fatigued and sluggish with
negative emotions. The neurotransmitter crash is often accompanied by low blood glucose levels,
which also contribute to fatigue.
*
Beta-endorphins relieve pain, reduce stress, enhance the immune system, and promote feelings of well-being. Serotonin
generates soothing and comforting feelings as it is released into the bloodstream. Serotonin is also involved with the
regulation of appetite, sleep, memory, learning, temperature, mood, behavior, and the cardiovascular, muscular and
endocrine systems.
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What role does protein play?
 Eating sources of complete and lean proteins throughout the day will help keep you energized and alert. It
will also help prevent blood sugar spikes that are caused by eating simple carbohydrates.
o Healthy sources of protein include: seafood, soy products, tofu, eggs, poultry, quinoa, low-fat and fatfree dairy, buckwheat, and hempseed.
o Many vegetable sources of protein do not contain all of the essential amino acids found in animal
products, but eating a variety of plant derived protein will supply the body with all essential amino
acids. Examples of vegetable protein sources include: legumes (black beans, pinto beans, chick peas,
lentils, etc.), peanuts, kale, cabbage, green beans, and oats.
 When choosing your sources of protein, consider how it was prepared.
What role does fat play?
 Eating a meal high in fat (more than 35% of calories from fat) will often leave you feeling sluggish, lethargic,
and unhappy, especially when the meal is consumed in the middle of the day.
 Aim for 20-35% of your total calories to come from fat, the majority of which should be from
monounsaturated and polyunsaturated fat which are found in nuts, fish, and vegetables.
o It is important to get enough fat in your diet for hormone regulation, the absorption of certain
vitamins, adequate energy, and healthy cell functioning.
 Eating a balance of Omega 3 Essential Fatty Acids (EFA) and Omega 6 EFA is helpful for improving mood
and achieving mental clarity. Ensure adequate amounts of both for the development of nerve cells.
o The adequate ration of Omega 6’s to Omega 3’s is 2:1.
o Current consumption in the U.S. is around 10-20:1. Try to increase your consumption of omega 3’s!
o Omega 3 fatty acids are found in anchovies, herring, mackerel, sardines, salmon, bluefish, tuna,
halibut, flax, canola oil, olive oil, soybean oil, and walnuts.
o Omega 6 fatty acids are found in flax, safflower oil, sunflower oil, corn oil, soybean oil, animal
products (e.g., egg yolks and organ meats), evening primrose, and black currant.
How can eating a healthy diet impact my brain function and ability to concentrate?
 Research indicates that consuming 2-3 servings of fish per week improves memory and brain function.
 Caffeine in small doses, 25mg per hour, can boost memory and concentration [25 mg is between 1/4 and 1/8
of an eight oz cup of coffee]. If you are sleeping 7-8 hours a night, caffeine will probably not be necessary to
help keep you alert.
o Too much caffeine can cause anxiety, “jittery” feelings, and other uncomfortable sensations. If you
are going to use caffeine, maximize your alertness by consuming 25 mg an hour. Stop caffeine intake
about 1½ hours before bed, at a minimum.
 Malnutrition: An insufficient intake of calories and/or nutrients results in undernourishment which can cause
lethargy, depression, anxiety, irritability, apathy, loss of concentration, and poor sleep patterns. All of these
symptoms will contribute to difficulty concentrating. Make sure you are getting enough to eat.
How can I achieve these mood and productivity benefits through my food?
 To help maintain steady blood sugar levels eat small meals and snacks regularly throughout the day. Try not
to go longer than 4-5 hours without eating.
 Organize your diet around these healthy foods:
o Make fruits and vegetables a central part of your diet. Aim for a variety of each.
o Complex carbohydrates: whole grains, root vegetables, beans, and legumes
o Lean protein: seafood and fish, legumes, poultry, and soy products
 Eat meals with a balance of carbohydrates, protein, and fat to avoid drastic blood sugar level changes.
 Try to keep your refined sugar intake to 10% or less of you total energy consumption; this will help avoid
blood sugar spikes.
 Include a source of lean protein in most meals and snacks to ensure you will have long lasting energy.
 Keep total fat intake to roughly 20-35% of your overall energy consumption. Avoid eating large quantities of
fat at one time, especially in the middle of the day, this will slow you down and cloud your ability to focus.
o Try to get most of your fat from healthy sources like fish, vegetables, and nuts, e.g., olive oil,
almonds, avocado, salmon, safflower oil, and flaxseed.
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Drink plenty of water, to calculate your minimum water requirement: take you weight in pounds, and divide it
by 2. This indicates the minimum number of ounces you need per day under typical circumstances. If you are
exercising, sick, or it is hot and/or humid you will need more water to stave off dehydration.
If you consume caffeine, cut back to 1-2 eight oz cups per day. Try to eliminate caffeine entirely if you suffer
from anxiety, have trouble sleeping, or are prone to headaches. Try substituting your usual caffeine source
with green tea, it has less caffeine and it is a great source of antioxidants.
Consider taking a multivitamin if you are under high amounts of stress. This includes being sick, getting an
inadequate amount of sleep, or being stressed. It is also worth considering if you have a poor diet.
More nutrition advice
 Eat breakfast everyday. Eat within one hour of waking up. Breakfast will boost your metabolism and give
you more energy for the day ahead. Try to include a whole grain, a source of protein, and fruit or vegetable in
your breakfast to get the most energy from it.
o Ex: whole grain cereal, sliced banana, low-fat or fat-free milk (or soy milk).
o Ex: whole grain toast with peanut butter, whole fruit (ex: apple, orange, mango, banana, grapes,
cherries, watermelon…), and a glass of low-fat or fat-free milk (or soy milk)
o Ex: a bowl of oatmeal with fresh or frozen fruit and almonds (or any nut) mixed in
 Eating a diet rich in whole grains, (e.g., oatmeal, whole wheat bread, brown rice, etc.), will provide you with
good sources of energy that will not disrupt blood sugar levels; they are also high in fiber.
o Research indicates that a diet rich in whole grains can reduce the risk of heart disease.
 Limit refined grains, (e.g., white bread, white rice, and pasta), potatoes, sugary drinks, and other sweets; these
foods often create surges in blood sugar which can lead to diabetes, heart disease, weight gain, and other
chronic conditions.
 Fish, poultry, and eggs are great sources of protein. Fish is high in omega-3 fats which are extremely
beneficial to the heart and brain. Poultry is a great source of protein and is lower in saturated fat than red
meat. Eggs are a great source of protein and other nutrients. Limit yourself to 3 yolks a week if you have
diabetes or heart disease (the egg whites are still a great source of protein on their own).
 Nuts, seeds, beans, and tofu are great sources of protein, fiber, vitamins, and minerals. Nuts and seeds
contain healthy fats and are good for your heart (in moderation).
 The majority of dietary fat should come from healthy fats and oils, (e.g., olive, canola, soy, corn, sunflower,
peanut, other vegetable oils, trans-fat-free margarines, nuts, seeds, avocadoes and fish). When these fats
replace highly processed carbohydrates and saturated fats they significantly improve cholesterol levels
reducing the risk of developing heart disease.
 A healthy diet rich in a variety of fruits and vegetables helps control total caloric intake, reduces the risk of
heart disease and stroke, protects against certain cancers, lowers blood pressure, and lowers cholesterol.
 Dairy products are a great source of calcium, vitamin D, and protein; to limit saturated fat, consume mainly
non-fat and low-fat dairy products. If you do not like dairy, or cannot consume it, then try soy products as an
alternative and consider taking a calcium and vitamin D supplement to meet your dietary needs.
 Limit salt/sodium consumption; high sodium diets are linked with increased risk of heart attack and stroke.
Resources:
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Bauer, Joy. Feel blue? Try leafy greens and other ‘mood foods’: What to eat to improve your mental health and
combat cranky behavior. 7/22/2008. [http://today.msnbc.msn.com/id/25790849/]. 12/5/2008.
Emmons, Henry and Rachel Kranz. (2006). The Chemistry of Joy: A Three-Step Program for Overcoming
Depression Through Western Science and Eastern Wisdom. New York: Simon & Schuster.
Harvard School of Public Health. The Nutrition Source: Food Pyramids: What Should You Really Eat?
Unknown. [http://www.hsph.harvard.edu/nutrition source/what-should-you-eat/pyramid-fullstory/index.html]. 12/8/1008.
Tufts University: Friedman School of Nutrition Science and Policy. Tufts Nutrition Magazine. 1/15/2009.
[http://nutrition.tufts.edu/1174562918759/Nutrition-Page-nl2w_1191330106602.html]. 1/21/2009.
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