Fatty Acids to Energy with Insulin Resistance

Walnuts arranged in a grid on a white dish

Recap: making energy for an insulin sensitive body

Other than the glucose from carbohydrates, fatty acids from fats are our second source of energy. My favourite fat-rich choices are macadamias and walnuts — perfect on a big cheese board together with camembert, gruyere, and gorgonzola.

So what happens as we digest all this delicious food?

Carbohydrates are broken down into glucose, proteins into amino acids, and fats into fatty acids and glycerol.1

You’ll remember that an increase in blood glucose levels tells our body to release insulin.

When this happens, your body begins converting the new, incoming fatty acids into triglycerides and storing them in your fat cells.

Your body also stops breaking down your existing fat storage. In other words, it stops turning triglycerides back into fatty acids. (These fatty acids are called free fatty acids to distinguish them from fatty acids from newly-digested fats.)2

All of this changes between meals, when insulin levels decrease. With low levels of insulin, the opposite happens: triglycerides are broken down into free fatty acids, which are then used to produce energy.3

Making energy for an insulin resistant body

When it comes to making energy from fats with insulin resistance, it’s not so much what happens immediately after a meal that’s important, it’s what happens between meals (when insulin levels drop).

When there is less insulin in the blood, your body resumes breaking triglycerides down into free fatty acids. With insulin resistance, it releases a lot more free fatty acids into the blood than it would if it were sensitive to insulin.4

The problem with too much free fatty acids

Free fatty acids accumulate in organs that are not designed to store fat — like your kidneys, liver, heart, and skeletal muscle.

Why is this so dangerous? It make it difficult to use free fatty acids for energy. It also leads to cell dysfunction and death in those organs. This condition is known as lipotoxicity.5

Fatty acids with insulin resistance

In short: with insulin resistance, fatty acids are not used efficiently for fuel, but accumulate outside of fat cells, causing damage to important organs.


  1. Charles Ophardt. “Overview of Metabolism.” Virtual Chembook, Elmhurst College, 2003, chemistry.elmhurst.edu/vchembook/5900verviewmet.html. ↩︎
  2. Robert Horn. “Insulin and Glucagon.” Medbio, medbio.info/horn/time%203-4/homeostasis_2.htm. ↩︎
    • Medbio is a website that addresses questions related to energy metabolism. All articles are written by Robert Stuart Horn, a professor from the University of Oslo’s Department of Medical Biochemistry.
  3. Jane Marie Vanderkooi. “Chapter 7-9 Fat and Ketoacids, Cholesterol, Repair.” Perelman School of Medicine, med.upenn.edu/biocbiop/faculty/vanderkooi/chap7-9.pdf. ↩︎
  4. Barry Sears and Mary Perry. “The Role of Fatty Acids in Insulin Resistance.” Lipids in Health and Disease, Volume 14, 2015, doi.org/10.1186/s12944-015-0123-1. ↩︎
  5. Barry Sears and Mary Perry. “The Role of Fatty Acids in Insulin Resistance.” Lipids in Health and Disease, Volume 14, 2015, doi.org/10.1186/s12944-015-0123-1. ↩︎
Published on 12 January 2018.