Burn: New Research Blows the Lid Off How We Really Burn Calories, Lose Weight, and Stay Healthy

by Herman Pontzer

How much energy does an average adult burn each day? Every nutrition label in the supermarket will tell you that the standard American diet is 2,000 calories a day—and every label is wrong.

You breathe most of it out as carbon dioxide, and turn a small fraction of it into water (but not necessarily sweat). If you didn’t know that already, you’re in good company; most doctors don’t, either.

This brings us to our last point about energy: it can be converted among its many forms—kinetic energy, heat, work, chemical energy, and so on—but it can never be lost.

Sugars are just small carbohydrates—little chains of carbon, hydrogen, and oxygen atoms. The smallest are just one sugar molecule big (hence the mono in their technical name, monosaccharides; saccharide just means sugar).

The monosaccharides are glucose, fructose, and galactose. The other sugars—sucrose, lactose, and maltose—consist of two monosaccharides stuck together and are called disaccharides (“two sugars”). Sucrose (table sugar) is just a glucose and fructose bound together. Lactose (milk sugar) is glucose and galactose. Maltose is two glucoses.

Understanding life in a real, functioning ecosystem requires us to abandon the romantic, Disneyesque mythologies that we’re fed growing up in our sheltered suburbias.