What is the main source of energy for the body?

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 currency⁴. 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.

To summarize: 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?

Why carbohydrates are the body’s preferred energy source

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

How does your body produce energy from carbohydrates?

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.

1. The central role of glucose: Brain cells, especially, rely on glucose as fuel for many critical functions, including ATP production, antioxidant support, and synthesis of neurotransmitters, neuromodulators, and structural components.⁷
2. ATP production: Once absorbed, glucose is quickly oxidized via glycolysis to produce ATP for energy.⁸
3. Indirect energy from the colon: Even undigested carbs are fermented by gut bacteria to become short‑chain fatty acids, which also contribute to human energy needs.⁹

What else does the body use for energy?

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.¹² Sunlight also enables vitamin D production,¹³ 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.¹⁴

Nutrients that support energy production

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.

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

How AG1 fits into daily energy support

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.

• Vitamin B1, also known as thiamine, is needed for energy metabolism and nervous system support.
  • Because the body doesn’t store large amounts of B1, it must be replenished regularly through diet or supplementation.
• Vitamin B2, also known as riboflavin, plays a central role in energy metabolism. It serves as a building block for coenzymes that drive many chemical reactions needed for cellular function and growth.
  • Because the body doesn’t store riboflavin in large amounts, it must be consumed regularly through diet or supplementation.
• Vitamin B3, also called niacin, is used to release energy from food and to support hundreds of biochemical reactions. It is naturally found in foods such as poultry, fish, whole grains, legumes, and some vegetables, and can also be formed in the body from the amino acid tryptophan.
  • Because the body uses it continuously and does not store large amounts of niacin, it must be consumed regularly through diet or supplementation. .
• Vitamin B5, also known as pantothenic acid, is essential for producing coenzyme A (CoA), a molecule required for many metabolic reactions. Nearly every cell in the body depends on B5 for its role in energy, hormone, and neurotransmitter function.
• Vitamin B6, also known as pyridoxine, plays a vital role in many of the body’s enzyme systems. It is required for over 100 metabolic reactions.¹⁶
  • Because the body doesn’t store large amounts of it, vitamin B6 must be obtained regularly through food or dietary supplements.

Read more about the vitamins in AG1 Next Gen

FAQs about energy in the body

Here are answers to some common questions about the body’s main sources of energy and how energy production works.

What is the main source of energy intake for the body?

Food in the form of macronutrients like carbohydrates, fats, and proteins is the body’s main energy source.

What gives the body the most energy?

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.

What makes up 90% of the stored energy in your body?

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

Support your energy levels with key nutrients

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.*

¹https://www.cell.com/current-biology/fulltext/S0960-9822(22)00765-5?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982222007655%3Fshowall%3Dtrue
²Ibid
³ https://www.ncbi.nlm.nih.gov/books/NBK553175/
⁴https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/cbic.202200064
⁵https://www.sciencedirect.com/science/chapter/referencework/abs/pii/B9780123849472001148?via%3Dihub
⁶https://www.cambridge.org/core/books/abs/part-1-mrcog-revision-notes-and-sample-sbas/carbohydrate-protein-and-lipid-metabolism/C51D6667B0DDE2433B6FC3CE31A1EB2A
⁷https://journals.physiology.org/doi/full/10.1152/physrev.00062.2017
⁸https://www.jbc.org/article/S0021-9258(24)02408-6/fulltext
⁹https://bmjopensem.bmj.com/content/7/2/e000930
¹⁰http://www.crcnetbase.com/doi/10.1201/9781315380728-18
¹¹https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2017.00324/full
¹²https://www.mdpi.com/2072-6643/15/6/1391
¹³https://onlinelibrary.wiley.com/doi/10.1111/phpp.12914
¹⁴Ibid
¹⁵https://www.sciencedirect.com/science/article/abs/pii/S0009279706000998?via%3Dihub
¹⁶https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/
¹⁷https://www.sciencedirect.com/science/article/abs/pii/S1751499111000060?via%3Dihub
¹⁸https://portlandpress.com/essaysbiochem/article-abstract/doi/10.1042/bse0420089/78257/Fatty-acid-metabolism-in-adipose-tissue-muscle-and?redirectedFrom=fulltext