Energy Expenditure Modes

As I mentioned in the last section, your body stores different macronutrient energy in different locations. Fats are stored in fat cells, and carbs are stored in the muscles and liver.

Both types of energy are stored simultaneously as they enter the body. The same can’t be said about when they are used.

Your body has an energy usage precedence; that is, if you have both types of stored energy, carbs are used until they are exhausted or near-exhausted, then fat can be used. This is because the body has two separate, exclusive “modes” for generating usable energy from stored macronutrients:

  • When your body is in glycolysis, it’s using carbohydrate as its main energy source. If the body has no stored carbohydrates and experiences significant carb intake, the body will switch to glycolysis immediately.
  • If you’re using fat as your primary energy source, you’re in ketosis. Ketosis begins naturally when you run out of stored carbohydrates through fasting or exercise. You want to stay in this mode as often as possible to maximize potential fat loss.

I’m omitting a lot of details and specifics, but they’re outside the scope of the guide. This is all you need to know about energy expenditure to meet your goals. If you’re interested, I recommend searching Google for more information on ketosis and glycolysis.

Quick side note: Since the body always uses carb energy first, some people refer to carbohydrates the body’s “preferred” energy source. However, this is misleading because the body is actually better at using fat for energy once fully adapted to ketosis. Carb-based energy has the highest usage precedence, that’s all.


Now that you have all of the background knowledge, let’s move on to a practical blueprint for fat loss.