Fatty acid oxidation

00:00 / 00:00



Fatty acid oxidation



Fatty acid oxidation


0 / 9 complete

USMLE® Step 1 questions

0 / 3 complete

High Yield Notes

10 pages


Fatty acid oxidation

of complete


USMLE® Step 1 style questions USMLE

of complete

Biochemistry researchers are studying the pathway of fatty acid oxidation with students in the laboratory. Which of the following is the rate-limiting step of fatty acid oxidation?  

External References

First Aid








β -oxidation of very-long-chain fatty acids (VLCFA) p. 45

Fatty acids

gluconeogenesis p. 76

metabolism of p. 45, 70, 87, 88

oxidation of p. 72, 72

synthesis p. 70

Metabolism p. 70-92

fatty acid p. 87


Our bodies are capable of surviving without food for long periods of time, at least 3-4 weeks with hydration!

The reason we can do that is that we can store our dietary fuels, and then break them down when needed to make energy in the form of adenosine triphosphate, or ATP.

Fat is one of the most important ways we store energy and the term “burning fat”, actually refers to fatty acid oxidation.

In fact, if two individuals were stranded in the Andes mountains with no food, the person with more fat content would survive longer - yet another reason to avoid working out.

What makes fat such a great source of energy are fatty acids, which are the simplest form of fats, composed of long chains of carbon and hydrogens.

The transfer of electrons in the form of hydrogen from these fatty acids to certain molecules, can then be used to generate ATP.

Fatty acid oxidation primarily takes place in the mitochondria of heart, skeletal muscle, and liver cells.

Before we can oxidize fat, it needs to be moved from storage sites to the cells that can use it. Fat is stored in adipocytes or fat cells as triglycerides, which are 3 fatty acids attached to a glycerol molecule.

Triglycerides can be broken down by the enzyme hormone sensitive lipase, into free fatty acids and glycerol. So if you’re starving in the Andes, first your blood glucose level falls.

In response, the pancreas secretes a hormone called glucagon which increases the activity of hormone sensitive lipase, and increases the breakdown of triglycerides.

Now, the free fatty acids can leave the fat cell, and enter the bloodstream, where they bind to a protein called albumin.

Albumin carries the fatty acids to target cells, like liver cells, that are capable of fatty acid oxidation. First, the free fatty acid dissociates from albumin and diffuses into the cell.

Once inside the cell, a cytosolic enzyme called fatty acyl-CoA synthetase adds a coenzyme A molecule to the end of the fatty acid, turning it into a metabolically active fatty acyl-CoA.


Fatty acid oxidation is the process your body uses to break down and uses fatty acids for energy. This process occurs in the mitochondria of your cells. During fatty acid oxidation, a fatty acid is broken down into two molecules of acetyl coenzyme A (CoA). These molecules are then used by the mitochondria to produce energy.


Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.