You may think you expend energy only when doing exercise, or when awake and moving around, but you are using energy all the time, even when you are asleep or lying still and relaxing. Energy is the basis of life. For example, your ability to maintain a healthy body temperature and support your breathing is called your basal metabolic rate, and you use more energy for these functions than for any other. Your body also uses energy to build new tissue, repair damaged tissue, and generate new, healthy cells. Even a simple eye movement requires energy.
How does my body keep energy flowing through my system all of the time?
You get all the energy you use from the food you eat, so sometimes we hear food talked about as if it were gas for a car engine. This is really not the best analogy, though, since gas is in a form that can be directly burned in the car engine, resulting in immediate energy. Food contains energy in the bonds that hold it together, but your body has the challenge of getting this energy released and then recapturing it, so it can be stored to be used later when and where it's most needed.
Producing energy in the form your body can use requires many steps, and food plays a number of roles. Some of the food you eat is broken down, and the energy in its bonds is stripped and transferred to molecules in your body that can immediately use the energy. Some of the foods you eat contain key nutrients -- vitamins and minerals -- that are necessary to support the energy transfer process. Some foods provide phytonutrients that protect your cells from incorrect or unbalanced energy production, which can cause damage to your cells and tissues. Still, other foods provide the building blocks for keeping your cells healthy, and since energy is produced within your cells, your cells need to have enough of the proteins involved in energy transfer and strong lipid membranes to competently transfer energy.
How does my body make energy from food?
The main types of food used to provide energy ' that is, the foods that are stripped of their energy, so it can be used by your body ' are carbohydrates and fats. Sometimes amino acids from proteins are used for this as well, but only when your body doesn't have enough of the carbohydrates and fats available. We often call this "burning" foods for energy, but it is really a process of breaking these molecules down piece by piece and transferring the energy that is released during this breakdown. The carbohydrate or fat is destroyed in the process. This breakdown of foods and transfer of energy requires oxygen, which you get from breathing, and results in carbon dioxide and water as waste products.
Carbohydrates and the glycemic index
Consumption of unhealthy high glycemic index foods is a common culprit in fatigue and energy problems; therefore, learning about the glycemic index so that you can make better food choices can make a major contribution towards resolving these problems. The glycemic index is a measure of how fast the carbohydrate in food is broken down to the simple sugar, glucose, which is then absorbed and quickly transported through your bloodstream to your cells. The glycemic index is determined by monitoring the blood sugar of several individuals after they eat a specific food, and foods are categorized from high to low glycemic index foods. The measure of high to low glycemic index, then, is a way to compare how quickly energy is released in your body from specific foods.
Foods that lead to a strong, fast blood sugar peak after consumption are called high glycemic index foods. These foods may give a quick burst of energy for the first hour or so after eating them, but research shows that this energy burst often goes down just as quickly, resulting in a slump or low energy feeling within a couple of hours after the meal. Foods that are high in simple carbohydrates, like sugar, are often high glycemic index foods. Examples of these foods are soft drinks, candy, pasta and pastries made from refined flour (white flour), and sweetened fruit juices.
The problem is that these foods often leave you with a slump after that quick energy burst is over, and a feeling of energy peaks and valleys may be experienced. These are the foods that can zap energy levels! High glycemic index foods are difficult to handle for people with insulin sensitivities, such as diabetics, and excessive intake of high-glycemic index foods is a major dietary contributor to fatigue.
Low-glycemic index foods are foods that release energy more slowly, resulting in a smaller change in the blood sugar level and a steadier, longer lasting feeling of energy. Chief among these foods are legumes, nuts, and seeds, but also included are root vegetables like celery root and rutabagas; leafy green vegetables; asparagus; artichokes; gourd family vegetables like pumpkin and cucumber; mustard family vegetables like broccoli and cabbage; and onion family vegetables like leeks and scallions.
It is not possible to indicate exactly which foods fall into each category for every individual by looking at the components of the food alone. This is because the glycemic index is not just a factor of the type and amount of carbohydrate, but is also influenced by how the carbohydrate is packaged; that is, the other components in the food. For example, refined flour is almost totally bare carbohydrate since most of its other components have been removed, whereas a whole grain product has protein and fats and other nutrients packaged with the carbohydrates. Research shows that this affects the way your body uses the carbohydrate and how well you can make and sustain energy after eating these foods. This one of the reasons foods made from whole grains, such as whole grain bread or pasta, are so much better for you.
Fats and energy?
Glycemic index is a measure of how quickly energy is released from a food, but since it measures blood sugar, it is presumed to be more indicative of carbohydrates (sugars) than other food components. Fats in a food lower the glycemic index, but they also provide energy on their own. Fats can be stored in the body for later energy production, which is one of the reasons our bodies accumulate fat.
Because excess dietary fat is so common among Americans, trimming excess fats from your diet has a good chance of helping you find more energy, regardless of your specific health condition. Strangely enough, even though we get plenty of fat in our diets, we usually come up short on the only fats we actually need'the essential fats called the omega-3 fatty acids. Sources of essential fats include cold-water fish (like salmon, cod, herring, sardines, sole, pike, perch, flounder, halibut, mackerel, and pollock) and all nuts and seeds.
Fiber and energy
Fiber is an indigestible part of many foods, so one might be inclined to downplay its importance in the creation and maintenance of energy. However, fiber is indispensable for the 'energy economy' of the body. Fiber (especially soluble fiber, like those in legumes, grains, nuts, and seeds) provides fuel for the friendly intestinal bacteria and supports healthy digestion, healthy fat metabolism and blood lipid levels.
More importantly for energy production, fiber can help slow the breakdown and absorption of sugar from high carbohydrate containing foods. Research has shown that the amount and type of fiber in a food can change its glycemic index and even make a high glycemic index food into a low glycemic index food. Sources of dietary fiber include legumes, grains, nuts, seeds, many root vegetables, fibrous fruits like berries, and leafy green vegetables. You may notice that these foods fall under the category of low-glycemic index foods, and it's no accident!
Nutrients that support energy transfer and storage
Because energy is so essential to life, it is probably not surprising that there are many enzymes and cellular components functioning together to maintain healthy energy levels in the body. These cellular components require a wide range of nutrients to function, and therefore, most essential vitamins and minerals play a role in the transfer and storage of energy. However, some nutrients are more central to maintaining healthy energy in your body.
After you eat food with carbohydrates or fats, these components are digested and absorbed into your body as fat or glucose (sugars). For more on how these foods are absorbed, see the FAQ How Does Digestion Work and How Can I Improve Mine?. Once in your body, the food molecules are taken to your cells where they will be stripped of their energy. The place where your cells get energy from food molecules is called the mitochondria. Mitochondria are like cells within your cells; they have a membrane made of fats and proteins like your cell's membrane and their own DNA. Mitochondria use oxygen and the nutrients in the food you eat to capture the food's energy.
The FAQ How Healthy Nutrition Builds Health, Starting with the Cells provides more information on how mitochondria capture energy from food to provide for your body to use. This energy transfer process uses a variety of enzymes to actually do the work of breaking down the food, and these enzymes require many vital nutrients to function. A multitude of vitamins is required for this process, in particular the B-vitamins: vitamins B1, B2, B3, B5 and B6. Their role in the functioning of the mitochondria is one reason the B-vitamins are considered the energy vitamins. Other nutrients, like coenzyme Q10 and L-carnitine, are also important in this process, as are many minerals like magnesium, iron and sulfur.
Good sources of the B-vitamins include whole grains since the B vitamins are concentrated in the bran of grains. Whole grains are an excellent source of the entire complement of energy-related B-vitamins. Iron is present in whole grains, and good food sources of sulfur are the cruciferous vegetables, like broccoli. Supplementation of Coenzyme Q10 in humans and animals has been shown to beneficially affect the efficiency of mitochondrial energy production and to protect mitochondrial DNA from free radical damage. Good dietary sources of Coenzyme Q10 include oils from nuts, fish and meat.
Phytonutrients that protect cells from imbalanced energy production
While it's not surprising that something as important as the generation of energy requires so many nutrients, it is a little surprising that the production of energy can also result in the offshoot production of dangerous molecules with potential to damage your cells. This is because the breakdown of foods and stripping and transferring of energy requires oxygen. During the production of energy, about 2% of the oxygen used escapes in the form of reactive oxygen species (ROS), a type of free radicals. Free radicals are oxidants, which are very reactive molecules that bind to and break DNA chains, directly causing mutations. They can also bind to and destroy proteins and fats in cell membranes.
When you are in good health, have low toxin exposure, and are eating a nutritious diet, your cells can protect against these ROS free radicals. With poor nutrition, or in the presence of toxins that inhibit or damage the energy transfer mechanics in your cells causing inadequate energy production, the amount of ROS free radicals generated in your cells exceeds the cells' ability to protect themselves against damage. When these damaging free radical by-products are not kept in check, which occurs, for example, when key nutrients are missing from your diet, ROS can bind to and destroy DNA, proteins, and the fats in your cells' membranes.
Over the past four decades, research has been continually showing that these damaging free radical by-products of energy production cause many of the fundamental alterations seen in aging and in chronic degenerative disease. Excess free radicals results in increased risk of premature aging, cataracts, and chronic degenerative diseases such as osteoarthritis, cardiovascular disease, diabetes, and cancer. Proper nutrition plays a critical role in neutralizing these damaging free radicals and protecting the health of your cells.
Research studies have shown an association between DNA mutations and defective energy transfer in cells with low levels of protective antioxidants; therefore, inadequate intake of protective antioxidants in food, such as phytonutrients like the catechins and anthocyanidins in green tea and fruits, and the oryzanol and ferulic acid in brown rice; vitamin C in citrus foods; vitamin E and tocopherols in whole grain oils and legumes; and carotenoids in carrots, cantaloupe, sweet potatoes and squash may result in a higher level of DNA mutation, predisposing you to conditions like cancer, as well as promoting fatigue and energy-deficit.
Research on animals suggests that lipoic acid supplementation increases mitochondrial membrane function and metabolic activity, and reduces the potential for oxidative damage. In addition, lipoic acid functions directly as an antioxidant and serves as a cofactor for maintaining the active states of coenzyme Q10 and vitamin E, both of which are important to the integrity of the mitochondria. Dietary sources of lipoic acid include potatoes, carrots, beets, and kohlrabi. Although not recommended since it is also loaded with cholesterol, red meat also contains alpha-lipoic acid.
For more on Reactive Oxygen Species and the World's Healthiest Foods see the section on mitochondria in the FAQ How Healthy Nutrition Builds Health, Starting with the Cells.
Supporting healthy cells for generating energy
Since energy is transferred and stored within your cells, it is no surprise that maintaining healthy levels of energy requires healthy cells. And, energy production from food also requires many factors other than just the machinery involved in the energy transfer process. As an example, think about what happens when you eat a meal. The sugar (glucose) is released and taken into your body through the digestion process, during which it enters your bloodstream. Your body responds to the glucose in your blood by secreting insulin from your pancreas into your bloodstream. When the insulin gets to one of your cells that needs glucose, it attaches to a protein (receptor) on the cell's surface, which then activates, or opens, a gate in the cell to let the glucose enter that cell. This glucose is then either used by the cell to produce energy or is stored for future energy production.
Much of the work of energy transfer in your body is performed by a variety of enzymes, which are proteins. Insulin is a peptide, made of the amino acids from the proteins in your diet. The insulin receptor on your cells is also a protein. The quality of protein in your body, and in these important energy support factors, is reflective of the quality of protein in your diet.
One key factor determining the quality of protein in foods is how well that food supplies the amino acids (building blocks of protein) you need in order to transform the food protein into yourself. All protein-containing foods provide a different profile of the essential amino acids as well as others that may be valuable. Another important consideration is eating protein-containing foods when your body can most efficiently use them to provide the energy you need when you need that energy. High-quality protein is found in foods such as fish, (preferably wild-caught, cold water fish, since they are also an excellent source of beneficial omega 3 fatty acids), organic eggs, legumes, grains, nuts and seeds, and vegetables.
The example above also shows how important healthy cell membranes are in supporting energy generation within your cells. Cell membranes are primarily made of fats, and these fats come from the food you eat. Research has shown that the fats you eat in food are reflective of the fats in your cell membranes. Poor nutrition, such as low intakes of the health-promoting omega-3 fatty acids and high intake of saturated fats may result in brittle, broken (leaky) cell membranes that can't function appropriately. Fats that support healthy cell membranes can be provided by cold-water fish oils (especially salmon), many nuts and seeds and their oils (especially flax, canola, pumpkin, borage, black currant, and evening primrose oils), and the oils of marine algae. The menus in the World's Healthiest Foods provide healthy fats for support of cellular health.
What is fatigue?
The creation of energy requires that you receive all the substances necessary and in about the right proportions (food, air, and water). These substances are broken down (digested), and absorbed in your intestinal tract, lungs and sometimes through your skin. The nutrients and substances necessary for your body's energy then need to be transported efficiently (through the actions of your heart, blood vessels, and cell membranes) to your cells, which receive them and then make energy from them. A feeling of health and vitality is also dependent on your body being able to remove all of the waste products that result from the energy production process. A problem in any of these areas can decrease your feeling of energy and lead to a feeling of fatigue.
Fatigue is a symptom rather than a disease, even if it is experienced all of the time. Fatigue is a symptom associated with many conditions and diseases and is not just related to the Chronic Fatigue Syndrome, which is a condition that is defined as a significant drop in overall energy for at least six months. Many people experience substantial fatigue, which can lead to other problems, without being diagnosed with Chronic Fatigue Syndrome, and this fatigue is not necessarily associated with physical or mental exertion. Fatigue may signal a need for modification of some everyday lifestyle habits in order to improve the body's 'energy economy' and decrease the likelihood of disease.
What can I do to improve my energy and promote my health and vitality?
Potential dietary causes and contributions to fatigue are as numerous as they are common. Dietary causes of fatigue can include consuming high glycemic foods or drinks that zap your energy, eating particular foods at the wrong time, or eating in a way that contributes to poor digestion. Foods that affect the body adversely, such as stimulants and alcohol, or food to which you are intolerant or allergic can also result in feelings of fatigue. Some of the contributors to fatigue are discussed below:
Stimulants and alcohol
Stimulants (especially coffee, espresso, and other strongly caffeinated beverages) and alcohol can contribute to fatigue because they represent a 'metabolic distraction' to a tired-out body already doing its best to cope with energetic challenges. The quick feeling of energy is usually generated out of a neurochemical (brain) message (stimulus) from these foods, but these foods do not support the increased need for energy from the stimulation that is felt after eating them. Instead, the body uses energy reserves, and then a slump or low energy feeling follows. Furthermore, caffeinated beverages have a diuretic (dehydrating) effect, which adds further stress to the body.
Alcohol places an extra burden of detoxification on the liver, a vital organ that may already be very busy processing other toxins (from foods, the environment, chemicals you may be exposed to at home, at work, or in traffic) as well as all of the fats you consume. Additionally, alcohol is also dehydrating to the body and can appear to your body much like a very high-glycemic index carbohydrate, which is a bane to an energetically-challenged body. Stimulants and alcohol can produce feelings of being on an energy rollercoaster and should be avoided or only used in moderation.
Food intolerance or allergic reactions are often ignored as causes of fatigue, but they can result in fatigue nonetheless. This is because they cause a stress to the body and result in responses like low-grade inflammatory reactions throughout the body. For more on Food sensitivities and other adverse food reactions, see our article on this subject.
Toxins and pesticides
Research has shown that diet can support healthy cellular energy production, DNA and membranes, and when the diet is nutrient deficient, these structures and functions become compromised. Pollution, certain artificial colors and preservatives, pesticides and other toxins also result in increasing free radicals in your body, which can further damage your cells' membranes and cause mutations in your cellular DNA. Furthermore, excess free radicals can also inhibit and even destroy the energy production machinery in the mitochondria, resulting in fatigue and a higher risk of chronic diseases. Therefore, support for healthy energy production includes decreasing this toxic exposure as much as possible. One way to decrease exposure to toxins is to select organically grown foods whenever possible.
Hydrogenated fats and saturated fats
Consumption of hydrogenated fats and a high intake of saturated fats have been shown to result in leaky, ineffective cell membranes. Leaky cell membranes can lead to a higher amount of free radicals, resulting in a decrease in effective energy production and a higher rate of DNA mutations. Avoiding hydrogenated fats and saturated fats, and using fat sources such as olive oil and flaxseed oil is one way to support healthy membranes. Also including sources of the essential fats, such as nuts, grains, and cold-water fish also help support healthy membranes.
Keys to support healthy energy