Key Takeaways
Macronutrients are the body’s main source of energy. Mitochondria in cells catabolize macronutrients into something called ATP, or adenosine triphosphate, for energy.
Carbohydrates are the body’s most direct source of energy.
The body can derive energy from indirect sources such as sunlight and stored reserves, but ultimately it requires nutrients to convert them into usable energy.
To bolster energy levels, fuel your body with its main, preferred sources of energy. Learn more about how your body produces the energy that supports your metabolism, cellular function, and physical performance.
How does the body produce energy?
In short, the body produces energy by converting food into cellular energy via the mitochondria.1
In more detail, the primary source of energy for the body is food. Macronutrients—carbohydrates, fats, and proteins—are broken down during digestion into the smaller, usable molecules of glucose, fatty acids, and amino acids.2
These smaller molecules act as raw materials for energy production. Your cells can extract energy from these nutrient molecules with the help of tiny structures called mitochondria. To take you back to Biology class, mitochondria generate energy through a series of biochemical reactions that process diet-derived nutrients into the energy-rich compound ATP, or adenosine triphosphate.
ATP is a molecule that exists in every living cell. It functions as the source of energy at the cellular level3—in other words, the cell’s main energy currency. When a cell needs to perform work, such as contracting a muscle, transmitting a nerve signal, or building new molecules, ATP is used as an energy source.Your body must continually replenish its energy supply (that is, eat consistent healthy meals) to maintain adequate levels of ATP in cells. Through the body’s energy cycle, nutrients—primarily obtained from food—are converted into ATP within the mitochondria. ATP provides the immediate energy required for essential biological functions. This process generates a continuous supply of cellular energy that powers the biological processes necessary for life and normal physiological function. Amazing, right?
Carbohydrates are widely known to be a major source of energy for the body. Studies show that the human body is highly efficient at digesting and absorbing carbohydrates, making them the quickest source of energy. In fact, carbs are so good at what they do, your body maintains highly regulated metabolic pathways to ensure a steady supply of glucose.5
As one study from Cambridge University explains it: “Carbohydrates are the chief components of diet (50–60% of energy per day must come from them). ...Glucose is the main carbohydrate involved in cellular energy production. It is central to all of metabolism. It is the universal fuel and source of carbon for the synthesis of most of the other compounds (both carbohydrate and noncarbohydrate).”6
During digestion, starches and sugars are broken down by salivary, pancreatic, and intestinal enzymes into monosaccharides—mainly glucose. From there, glucose is absorbed from the intestine into the circulation and transported to all the cells of the body. As with all nutrients, your cell mitochondria channel glucose into ATP production or short‑term storage.
While food is the main source of energy for the body, your body has many ways of keeping energized even when there isn’t sufficient nutritious fuel. The main mechanisms include:
1. The body keeps energy reserves.
Even when you are not eating, the body can produce energy from its stored reserves. These include glycogen stored in the liver and muscles, body fat stored as triglycerides, and in some situations, proteins from muscle tissue. The body can break any of these down to generate ATP.10
2. The body releases energy through oxygen.
Oxygen is essential for a process called oxidative phosphorylation, the metabolic pathway in which energy is generated in mitochondria.11 Oxygen is not an energy source itself, but it is essential for extracting energy efficiently from nutrients and stored fuels.
3. The body absorbs the energy of sunlight.
Humans cannot convert sunlight directly into chemical energy like plants, but sunlight still plays an important role in regulating the body’s energy systems—primarily through its effect on circadian rhythms, which impact hormones such as melatonin and cortisol, which in turn influence metabolism, alertness, and sleep cycles. Sunlight also enables vitamin D production, which affects various physiological processes related to energy and overall health. Sunlight exposure supports vitamin D production, which plays a role in various physiological processes related to cardiovascular and metabolic health.
High-quality, nutritious food remains the best source of energy for the body.
Your body needs to receive frequent fuel in the form of macronutrients: complex carbohydrates, healthy fats, and sufficient protein.
Carbohydrates | Healthy fats | Proteins |
|---|---|---|
Whole grains (oats, brown rice, quinoa) Fruits Potatoes or sweet potatoes Beans and legumes | Avocados Olive oil Nuts and seeds |
Micronutrients also support energy production for daily function. Micronutrients include vitamins and minerals (particularly B vitamins) that act as coenzymes that help convert carbohydrates into energy.15
AG1 contains B Complex vitamins (those micronutrients we mentioned) in its formula, which can help support your body’s energy needs. One scoop of AG1 per day can support your metabolism and help maintain energy levels as part of your daily routine. AG1 Next Gen includes B vitamins that act as cofactors in your body's natural energy production process—helping unlock energy from the food you eat.
Put another way, the food you eat contains energy. B vitamins, like those in AG1, help unlock the energy in food.
Here are answers to some common questions about the body’s main sources of energy and how energy production works.
Food in the form of macronutrients like carbohydrates, fats, and proteins is the body’s main energy source.
Carbohydrates provide the body with the quickest energy source, glucose. Other macronutrients, such as healthy fats and proteins, also contribute energy, but in less direct ways. Micronutrients such as vitamin B also contribute to energy production.
About 90% of the stored energy in the human body is in the form of fat.17 Fat is the largest energy reserve in mammals.18
The body is an incredible and complex machine that requires energy to function. AG1 supports healthy energy levels by providing the necessary nutrients to support cellular function, as well as the Vitamin B complex, which contributes to energy production.*
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10. Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E. Glycogen metabolism in humans. BBA Clin. 2016;5:85-100. doi:10.1016/j.bbacli.2016.02.001.
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12. Ishihara A, Courville AB, Chen KY. The Complex Effects of Light on Metabolism in Humans. Nutrients. 2023; 15(6):1391. https://doi.org/10.3390/nu15061391
Eggs Chicken or fish Beans and lentils Tofu and dairy |
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16. Office of Dietary Supplements, National Institutes of Health. Vitamin B6—health professional fact sheet. Updated February 28, 2023. Accessed May 12, 2026. https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/
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