This article is an excerpt from the Shortform book guide to "The 4-Hour Body" by Timothy Ferriss. Shortform has the world's best summaries and analyses of books you should be reading.
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What are calories? Why is understanding calories important and how does the 4-Hour Body help?
Calories are often a focus for people who are dieting, but they may not be as important as you think for changing your body. Understanding calories is one of the preliminary steps to body recomposition in The 4-Hour Body.
Read more about understanding calories and what that means for body recomposition.
Understanding Calories
The calorie was invented by Wilbur Olin Atwater in the nineteenth century. He measured calories by incinerating food. However, humans don’t incinerate food when they eat; digestion is a far more complicated chemical process. (For example, eating a piece of firewood isn’t going to release the same amount of energy into your body that would be released into the air if the log were burned.) As a result, the calorie isn’t a particularly useful measure when it comes to body recomposition because it’s not an accurate measure of how much energy you’re actually getting from digesting food.
Therefore, when understanding calories and your intake and outtake of them, it’s important to keep the following in mind:
- Anything you ingest needs to make it to your bloodstream to have an effect. If it goes through your body without being absorbed, your body doesn’t change in any way. (Shortform note: Today’s food calorie calculations are adjusted for absorption.)
- The body responds differently to calories from fat, protein, and carbohydrates—each produces a different hormonal response. For example, in a study of people on semistarvation diets:
- The people who ate 90% fat lost 0.9 pounds a day.
- The people who ate 90% protein lost 0.6 pounds a day.
- The people who ate 90% carbohydrates lost 0.24 pounds a day.
- Exercise isn’t the only (or best) way to burn calories. It’s only the most commonly cited because it’s easy to measure and scientists, under pressure to constantly publish, choose easier studies, and then to justify them, inflate their importance. Drugs and changes in body temperature also burn calories.
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Here's what you'll find in our full The 4-Hour Body summary :
- How to do the least amount you need to do for the results you want
- Why you need a cheat day in your diet
- How to improve everything about your body, including sleep, sex, and longevity
