Metabolism Basics

There are 3 types of nutrients that your body uses for energy

Carbohydrates:  Starchy foods like rice, potatoes and pasta and even green beans, sugars, grains and cereals.

Your body breaks these foods down in to glucose, also known as blood sugar. Cells throughout the body use the glucose as the energy to perform their various functions.  Any unused glucose is converted into fat or glycogen and stored for later use. 1

Protein:  Foods like meat, eggs fish and cheeses

So much of the body is made of, and/or requires protein to function. It is the building foundation for collagen, tendons, and muscles, is necessary for growth and repair of cells. Most importantly in a ketogenic meal plan protein can serve as a metabolic fuel source. “Proteins are not stored for later use, so excess proteins must be converted into glucose or triglycerides, and used to supply energy or build energy reserves. Although the body can synthesize proteins from amino acids, food is an important source of those amino acids, especially because humans cannot synthesize all of the 20 amino acids used to build proteins”. 2

Fats: (or triglycerides) Foods like, butter, vegetable oils, and animal fat

Fats are taken in as food or synthesized by the breakdown of existing fat already stored in the liver and throughout the body into fatty acids and glycerol. These components are used in the body’s normal energy generation pathway. Because one triglyceride molecule yields three fatty acid molecules with as much as 16 or more carbons in each one, fat molecules yield more energy than carbohydrates and are an important source of energy for the human body. Triglycerides yield more than twice the energy per unit mass when compared to carbohydrates and proteins”.2 As a result, when blood sugar (carbohydrate) levels are low, triglycerides can be converted into smaller molecules and used for your body’s energy requirements!


  1. Ramos, A., & Hughes, A. C. (2016). The complete ketogenic diet for beginners: your essential guide to living the keto lifestyle. Berkeley, CA: Rockridge Press.