If one gram of fat contains 9 calories, and there are about 454 grams in a pound, how come 1 pound of fat is commonly equated to be about 3,500 calories instead of about 4,000 calories?

Question

If one gram of fat contains 9 calories, and there are about 454 grams in a pound, how come 1 pound of fat is commonly equated to be about 3,500 calories instead of about 4,000 calories?

In: 10

Answer 1

You’re right that if you do the math, 1 gram of fat (which contains about 9 calories) times 454 grams in a pound would give you about 4,086 calories in a pound of fat.

However, when we’re talking about body weight and losing or gaining fat, we’re not talking about pure fat. Body fat is not 100% pure fat but also contains some amount of water and proteins. The fat in our bodies isn’t like the cooking oil in your kitchen or the butter on your toast – it’s a bit more complex.

Researchers have found that each pound of body fat is more like 87% fat. If you do the calculation with that in mind, you’ll find that each pound of body fat contributes about 3,500 calories (0.87 * 4,086 calories ≈ 3,555 calories, which is often rounded to 3,500 for simplicity).

So, when you hear that you need to burn about 3,500 calories to lose a pound, it’s because you’re not just losing pure fat, but also some water and proteins along with it.