What is a calorie?

Explore the complex relationship between calories and weight

What if you found out that weight loss is actually much more complex than "calories in, calories out" and that the 2,000 calorie-a-day recommendation may not actually be accurate?

How 'vibes' factor into scientists' decisions about using certain units

Although there are absolute quantities from which units can be defined, such as the speed of light and the corresponding light year for distance, the usefulness of units comes from their ability to easily communicate values, rather than how fundamental their origins are. For example, while Kelvin measures absolute temperature, Celsius is scaled to the temperatures of boiling and freezing water, making them more practical for everyday usage.

What is metabolic rate?

Read this article to better understand the concept of metabolic rate, which is defined as the amount of energy expended by an organism over the course of a day. Basic metabolic rate (or BMR) is this metabolic rate at rest, during which the body only...

A temperature of absolute zero is impossible to reach

Zero on the Kelvin scale—equivalent to -273.15 degrees Celsius—describes a system where all atomic motion completely stops, which is forbidden according to thermodynamics. As of 2025, the closest scientists have gotten to absolute zero is 0.00000000004 K.

Counting calories with a ballerina

Ballet dancer Theresa Farrell meticulously manages her diet to achieve her performance weight goal for the American Contemporary Ballet season in Los Angeles. She tracks calories, relies on pre-packaged meals, and calculates every intake. This regimen allows her to stay focused on training and rigorous dance routines, ensuring she's prepared physically for performances. Watch a day in the life here.

Is metabolism related to weight loss?

Read this article to better understand metabolism and why doctors say it's only one piece in the puzzle to managing weight. Metabolism breaks down and converts what we consume into energy, which provides fuel for all of our body's functions—both...

Cookies were originally used as low-stakes ways to test the temperature of an oven

In 7th century Persia, bakers used small mounds of dough to test the heat in ovens before baking larger cakes. Afterward, they'd add honey, nuts, and other items to the small mounds, creating early cookies.

Metabolism, a collection of chemical reactions at the cellular level, processes food and converts it into energy to power the body.

Since 1983, the meter has been defined based on the speed of light

The 1875 Metre Convention established the unit as the length between two lines inscribed on the surface of bars made by the International Bureau of Weights and Measures. Advancements in the measurement of light redefined it as the distance light travels in 1/299,792,458 of a second.

Everything with a temperature above absolute zero emits light at nearly all wavelengths

Thermal radiation results from random motions of particles that make up an object, which only theoretically cease at 0 Kelvin, or -273.15 degrees Celsius. The greatest intensity of thermal radiation, also known as blackbody radiation, is emitted at a characteristic wavelength corresponding to the object's surface temperature.

T. rex needed the same amount of calories as 80 people every day

Tyrannosaurus rex is the most extensively studied fossil creature ever known. Every year, new research is added to the towering list of papers that try to draw …

Data suggests the typical horse produces over 12 horsepower—a unit of measurement for the rate of work done that was conceived as a marketing tool to communicate steam engine performance.

Fascinating evolution of the oven

From ancient wood-fired ovens in Rome and Egypt to modern microwaves, the oven’s evolution has shaped how we cook. Early ovens focused on heat retention, but breakthroughs like the gas stove in 1834, and the electric stove in 1892, brought precision. Then, in 1967, the microwave redefined convenience.

The Kardashev scale measures a civilization's advancement based on energy use

Developed by Russian astrophysicist Nikolai Kardashev in 1964, the scale classifies a civilization based on the amount of energy its existing technologies can harness, ranging from a society that consumes as much energy as a single planet to one that consumes as much energy as an entire galaxy.

Understanding the 1.5 degree Celsius climate benchmark

As more parts of the world are facing extreme weather, from high temperatures to increased natural disasters, there is much debate about what can be done. MIT News explores and explains the 1.5-degree benchmark for limiting the effects of climate change. Read to understand where the planet stands in relation to this threshold and what can be done at the global, regional, and personal levels to “keep 1.5 alive.”

What is a heat dome?

The world is seeing regular heat waves with multiple causes, including so-called "heat domes," a term rising in use in recent years. A heat dome occurs when the atmosphere traps hot ocean air like a lid or cap, creating stifling conditions and resulting in extended periods of heat. See an illustration of this phenomenon and read how it works with this brief explainer.

Why is rice so popular?

From Spanish paella to West African jollof rice, rice is a staple in dishes across the world. This colorful animated video dives into the global expansion of rice, which contributes more than 20% of the calories consumed by humans each year. Learn about rice’s beginnings thousands of years ago, the environmental consequences of its popularity, and the potential for positive changes in the future.

Ketchup, 101

Ketchup is a tomato-based condiment mixed with vinegar, salt, and spices. The word likely originates from Southeast Asia, where it was used for a common fish brine sauce in the 18th century. For a brief period in the early 19th century, ketchup was viewed and marketed as a medicine. Henry John Heinz formulated a standard recipe in the late 1800s.

Infrared light is most often associated with thermal radiation and cooking food

Although extensively used in remote controls for electronics, where LED lights send signals wirelessly, infrared cameras allow for night vision and thermography—imaging of heat patterns in the body to non-invasively reveal blood flow for supplementary diagnostics. Infrared radiation also provides heat in toasters, saunas, and other technologies.

How does your body turn food into energy?

Cells get energy via a process known as cellular respiration, which involves turning glucose into ATP or adenosine triphosphate. Breaking the phosphate bonds of ATP results in usable energy being released into cells, which can then use that energy to power biological processes. This 10-minute video explains how glucose turns into ATP, giving the body the energy it needs to survive.

Tracing the history of refrigeration

Refrigeration has become critical to most of our lives. But not long ago, it wasn't available. How did we become so dependent on our fridges and freezers? This fun, informative podcast traces the history of keeping it cool with ice and...

Learn the history of food science breakthroughs from the 20th century

Long after humans developed the means to produce sufficient food to feed civilizations, scientific research focused on a wide variety of objectives, such as developing methods to preserve food quality (accomplished via frozen food), speeding up cooking (leading to the microwave), and lowering the cost of sweetening food, which high fructose corn syrup provides.

Americans consume 8.3 billion calories of turkey on Thanksgiving

Individuals consume an average of 3,150 to 4,500 calories at the meal, which takes the average male 10 hours to burn off.

The impact of greenhouse gases is assessed as a measure of Global Warming Potential

Since 1990, the Intergovernmental Panel on Climate Change has used GWP to measure how much energy 1 metric ton of a gas emits over a given period—usually 100 years—relative to 1 metric ton of carbon dioxide. By definition, carbon dioxide has a GWP of 1.

A caffeine calculator

This simple calculator takes your preferred caffeinated drink and your body weight to determine how much is the right amount, and how much might kill you. In case you've ever had the morbid curiosity about just how much of that tea you'd have to drink to doze off forever. Find out your moderate and lethal doses here, as well as some extra info on caffeine consumption.

Particle accelerators detect subatomic particles using millions of sensors

Calorimeters measure the energy of particles. Tracking devices can measure momentum and charge from the trajectory of particles, which is determined by recording tiny electrical signals. Time-of-flight detectors provide particle velocities directly and particle mass indirectly, giving physicists a suite of properties to compare with those of known matter.

Biologist Richard Dawkins coined the term 'meme'

His 1976 book "The Selfish Gene" proposed that units of culture could be replicated, passed on, and evolve as they were transmitted, similar to human genes. He called this unit a "meme," to be pronounced like "cream."

A brief explainer on food expiration dates and what they really mean

Roughly 20% of food items in the US are thrown out because consumers don't understand how to interpret expiration labels. Over time, when supermarkets began carrying processed foods, grocers use packaging codes to track how long foods had been on...

How the sun heats the Earth

We all know it: Without the sun's heat, the Earth would be uninhabitable. So how does it work? The sun fuses roughly 600 million tons of hydrogen every second, the energy from which bursts out into space—including toward our planet. Our atmosphere...

Why is there a Vitamin K but no Vitamin F?

The first vitamin was identified in 1913 by an American scientist performing rat studies while investigating dairy cattle nutritional needs. Elmer Vernon McCollum called this first vitamin, found in butter and egg yolk, "fat-soluble factor A." This...

Fifteen answers to 'what is the meaning of life?'

Writer James Bailey repeated philosopher Will Durant's 1932 project soliciting opinions on the meaning of life from a variety of luminaries. In this article, read the fascinating responses people gave to the all-important question, from renowned author Hilary Mantel to a seasoned palliative care supporter who had witnessed dozens of deaths.

What's your ACE score, and what does that mean for your health?

An ACE score is a way of measuring adverse childhood experiences, which can negatively impact health outcomes. Take this quiz to determine your score and what that means for your health. The Centers for Disease Control and Prevention and Kaiser...

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.

Explore 'The Big Mac Index,' an economic indicator created by The Economist as a cheeky reference for the purchasing power of consumers across different countries.

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.

Watch an animation of what happens inside cookies as they bake in an oven

As temperatures rise and butter melts, trapped water expands, spreading the dough, which remains held together by a network of proteins. Maillard reactions produce browning on the surface beyond 310 degrees Fahrenheit (154 degrees Celsius), while caramelization can be triggered by baking past 356 degrees Fahrenheit (180 degrees Celsius).

Understanding why the thermosphere feels cold, despite exceeding 2,000 degrees Celsius

High-energy solar radiation can raise temperatures above 2,000 degrees Celsius (3,632 degrees Fahrenheit), but the air density in this layer is so low that there would be insufficient collisions between energized molecules and a person's skin to cause them to experience this warmth. Variations in the level of solar radiation reaching the layer cause it to swell and shrink.

The evolution of the human diet

Could eating like our ancestors make us healthier? One estimate suggests prehistoric hunter-gatherer communities obtained 75% of their calories from meat and fish.

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

Barbecue relies on a unique scientific equation

Barbecue's distinct flavor starts with an interaction between the heat source and food, which creates a Maillard Reaction—better known to diners as those crunchy, caramelized bits on the outside.

The top several meters of the world's oceans can hold as much thermal energy as the entire atmosphere.

Pyramid or plate? Why nutrition guidelines change

Those who remember growing up with the age-old food pyramid may be resistant to dietary guidelines changing, but experts agree that the food pyramid recommendations held serious flaws. It suggested, for instance, that meat and junk food were meant...

Explaining the unified atomic mass units, which quantifies the mass of atoms and molecules

Until 1961, the atomic mass unit was defined based on oxygen-16, but it was later replaced by the unified atomic mass unit, defined as 1/12th the mass of a carbon-12 atom. Today, the term "atomic mass unit" often refers to the "unified atomic mass unit," denoted by the symbol u.

'Weight cycling'—when someone repeatedly loses and gains weight—can harm an individual's metabolism.

The history of the McDonald's Happy Meal

The McDonald's Happy Meal is the quintessential fast food kids meal, serving up child-appropriate portions and prizes all within a portable, fun container. So where did this pop culture icon begin? Watch this quirky 13-minute history of the Happy...

On average, the human body produces about 100 watts of electricity—enough to power a light bulb—but some people can produce over 2,000 watts in short bursts, such as when sprinting.

Can we speed up our metabolisms?

Listen to this 31-minute podcast to better understand what science knows and doesn't know about metabolism, as well as the only thing that seems capable of changing it. Scientists understand that the difference between a so-called “fast” and “slow” metabolism does not affect one’s ability to lose weight.

Mapping the origins of the world's crops

Food has evolved alongside humanity, and through globalized trade, much of the world can enjoy foods once isolated to one region. Examine where your favorite foods originated from and see how diet differs across cultures with these interactive...

What exactly is dopamine?

Dopamine is a neurotransmitter—a chemical released by neurons that enables neural communication—that makes people want things with an "almost animalistic desire," compelling them to snack or check phone notifications. Often misrepresented as a "pleasure" chemical, dopamine is involved in motivation, learning, attention, habit formation, and more. Trends like dopamine fasting overinflate its role in mental health and often use it as part of "straw man" biohacking claims.

Can fasting help you live longer?

Animal studies into the health benefits of calorie restrictions of 20%-40% suggest it extends life spans and reduces incidents of age-related diseases, including cancer. This article explores the research into fasting, calorie restriction, and longevity.