How does your body turn food into energy?

How metabolism, when cells convert molecules into energy, works

Metabolism is when a cell’s internal network of chemical reactions breaks down food molecules and transforms them into pieces of the cell itself. Sometimes, cells build replacements for worn-out parts. Other times, they build energy molecules that power the cell’s activities.

An overview of oxygenic photosynthesis, which releases oxygen from breaking down water

Within the membranes of chloroplasts, electrons in pigments are energized by light and transferred across a series of molecules until they create the energetic NADPH molecule. This transfer also powers a hydrogen pump, which creates an ion imbalance that, when relieved, produces energetic ATP molecules. Outside the membranes, both NADPH and ATP are used to synthesize G3Ps, which are funneled into other metabolic pathways to produce sugars.

Why death is caused by a dearth of ATP

Though people die from many causes, this video makes the case that a lack of adenosine triphosphate production in the body is what kills almost all of us. Without ATP, physiological processes grind to a halt, and organs stop functioning.

The stages of fasting

What happens to the body when it goes without caloric intake? This article overviews the immediate physical effects of fasting. Within a day of going without food, the body will have used up its glucose stores and ordered the liver and muscles to convert their glycogen (glucose storage) into usable glucose. By the second day, glycogen stores will run out, forcing the body to use fat as energy. This process is known as ketosis.

What is a cell? A great quick overview.

YourGenome.org furnishes a collection of information on cells and how they work. Every body has trillions of cells, each serving a specific function: making proteins, processing chemicals, and creating energy. Every cell contains a genome, a set of instructions for the cell's function. Brush up on your cells for a better grasp on genetics.

An explanation of the Calvin cycle, including why it needs to run six times to create glucose

Each run of this second phase of photosynthesis begins with a five-carbon molecule called RuBP, which gains an additional carbon atom when carbon dioxide (CO₂) is attached. Across six cycles, the six six-carbon molecules—36 carbon atoms in total—are processed into 12 three-carbon sugars, which can be used to generate glucose, and six RuBP molecules, enough for each cycle to restart.

How humans digest food

Every day, the average human eats close to six pounds of food—all of which must be processed by the digestive system. Ten organs collaborate to transform food that the mouth chews into the energy needed to stay alive. (Stretched out, these organs...

Insulin is a hormone that controls blood sugar by helping absorb it into cells

Blood sugar levels increase after a meal when the body starts turning food into usable fuel—sugars, proteins, and more—which are absorbed into the bloodstream through the intestines. Blood sugar levels rise, releasing insulin, and letting sugar in the blood be absorbed into hungry cells, thereby dropping blood sugar levels.

Visualize what happens to atoms during nuclear fission and how the process produces energy

Nuclear fission occurs when an unstable, often massive, atomic nucleus splits into smaller ones—daughter atoms—and releases energy. Within a nuclear reactor, these daughter atoms can collide and combine with neighboring atoms, destabilizing them and triggering a chain reaction of atomic splitting.

Batteries store energy in chemical bonds that can be turned into electricity

To achieve a more stable, nonreactive state, many elements in nature are reactive and will seek to lose electrons via oxidation or gain electrons through reduction reactions. By pairing an oxidizing chemical with a reducing chemical in a battery, electrons will naturally flow between them, producing an electric current.

How humans breathe without thinking about it

We breathe without thinking about it thanks to the body’s respiratory system and autonomic nervous system, which controls vital functions. Breathing transports oxygen to the body’s cells to keep them working and clears the body of carbon...

How fermentation works

Alcoholic fermentation is the process where yeast transforms grape sugars into ethanol, creating wine. Microscopic fungi (commonly known as yeast) metabolize sugars, producing alcohol and carbon dioxide. Fermentation's speed and temperature impact wine's flavor and style: cooler temps suit fruity whites, while warmer ones enhance red's tannins. Fermentation stops when sugars are depleted or by temperature extremes, and sometimes yeast removal yields sweeter wines. Get a quick breakdown of the process with this easy explainer.

Light energy can be transformed into electricity in solar cells via the photovoltaic effect

When light strikes semiconducting material, it can knock electrons out of atoms, creating a charge imbalance within the material. A wire connecting the oppositely charged regions can allow electrons to flow back, balancing the charges and producing an electric current that can be harnessed to power devices.

What do vitamins actually do?

Vitamins are molecular tools the body needs to carry out regular cellular processes, such as wound healing. This 45-minute video dives into the science behind vitamins and their role in the body. There are 13 essential vitamins that must be...

Honeybees vomit nectar into one another's mouths to transform it into honey

Digestive enzymes break down long chains of complex sugars into simple monosaccharides, while the fanning of their wings helps honeybees evaporate water away. This process increases the acidity of the resulting honey, increasing its shelf life when sealed in beeswax.

Most cells undergo programmed, controlled death

In the average adult human, apoptosis occurs in 50 billion to 70 billion cells daily when proteins managing a cell's life cycle send signals that the cell is damaged, causing it to break apart into smaller pieces that are consumed by white blood cells. The consumption prevents damage from spreading via cell division.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

Landfills capture methane gas and convert it into usable energy

As organic waste breaks down underground, it produces landfill gas that is roughly 50% methane. That gas can be captured and used to generate electricity or provide heat for nearby homes and businesses.

Renewable energy basics

Discover the many benefits to using renewable energy resources, but what is it exactly? From solar to wind, it’s the fastest-growing source of energy in the world – and how we can use it to combat climate change.

What happens to your brain when you burn out?

You've probably heard of burnout, also known as the feeling of exhaustion that happens after a long period of being overwhelmed or stressed. It's often associated with work and careers, but other parts of life, like parenting, can cause burnout, too. Scientists are figuring out what happens, biochemically speaking, in the brain when burnout hits—and spoiler alert, it includes a neurotransmitter called glutamate. Watch this video to learn more.

How to turn any cell of the body into a stem cell

Scientists have developed techniques allowing them to 'reprogram' any cell in the body into an induced pluripotent stem (iPS) cell, which can be used to create either more stem cells or specialized cells for use in experimental medical treatments. This page gives readers a brief introduction to the history of iPS cells, what researchers are studying with iPS cells, and challenges associated with iPS research.

The surprising science behind Pop Rocks

Have you ever wondered why Pop Rocks makes tiny explosions in your mouth? Well, there’s actually pressurized carbon dioxide bubbles trapped within the sugary candy. This 19-second video shows you what Pop Rocks look like under a microscope.

How microchips are made

Our increasingly electronic world depends on tiny devices called microchips to function. It takes half a year to create one, which is approximately the size of a fingernail. Engineering them is a highly involved process that starts with silicon-rich sand and eventually turns into billions of transistors packed into one small area. Watch this video to understand the complex feat of creating microchips and how they’re relevant to our daily life.

How heart transplants work

Heart transplants require an old heart to be removed and a new one to be installed without killing the patient. How does that work? In this easy-to-understand five-minute video, learn each step of the intricate process, from donor matching to the preservative solution a heart is doused in while it is transported.

VO2 max measures the body's ability to use oxygen to produce energy

VO2 max is the maximum rate at which the body can use oxygen to aerobically produce energy—adenosine triphosphate—for use during intense exercise. Aerobic exercise increases VO2 max, counteracting age-related decline by increasing the body's capillary count and remodeling the heart's left ventricle, increasing the amount of blood it pumps.

How tea gets made

Tea is one of the most consumed beverages in the world, and this video walks us through the process of supplying it from farms to our mugs. Workers handpick leaves, ferment them, and dry them as part of this involved operation. Follow along for a scientific understanding of the many steps it takes to produce tea and appreciate the detail and effort to create its flavor, aroma, and color.

How fusion—which releases energy when two lighter atoms combine to form a heavier atom—differs from fission

Watch what the Ebola virus does inside our cells and organs in order to spread and survive.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Tattoos remain visible on your skin thanks to immune cells called macrophages

Some renewable energy sources may weaken the resiliency of electric grids by removing outage buffers provided by coal- and natural gas-fired plants, which provide the system with more time to find a new power source if a plant goes down.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

The history of many kitchen appliances involves unexpected discoveries and applications, including wartime radar turned hamster defroster and replacing an 'ice king' with heat-stealing boxes.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Coral reefs get their colors from zooxanthellae—microorganisms that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

After 25 people used virtual reality headsets to practice flying with virtual wings—flapping their arms—their visual cortex responded to the wings almost as if they were real arms, treating them as body parts.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

How Amazon operates a 'flywheel' business model, a self-reinforcing cycle that drives continuous growth

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

Telehealth demand for GLP-1s for weight loss is booming as consumers seek easier access.

An initial public offering or 'IPO' is the process of a private company becoming public by putting shares of the company on the stock market for purchase.

Children are now three times more likely to say they want to be a YouTuber when they grow up than an astronaut, with some even attending 'YouTube camps' that teach kids how to create content for the platform.

Lesser-known phobias include turophobia, or the fear of cheese, and nomophobia, the fear of being without your cell phone.

After the Boston Tea Party, colonists switched to coffee, which became the main morning drink for revolutionaries.

The first steps to rebuilding your credit score include getting to know exactly what's on your credit report and figuring out how far you are from the '700 club,' or 'good score' range.

The price of gas is a composite made up of several different factors, with the federal gas tax making up less than 20% of what drivers pay at the pump.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.