How does the body release and store fat?

Energy metabolism and nutrition go hand in hand. Through our diet we get our nutrients: carbohydrates, fats and proteins. Inside our bodies these molecules get broken down into smaller components, rearranged, stored (especially after a meal), released from these stores (between meals or during a fast) and further metabolized. Scroll through the animations on this page to learn about what happens to fat, why our body requires it, and what our body does with it. The relative contributions of glucose and fatty acids to energy production in the body change over a 24-hour period with meal intake: fatty acids contribute to overnight whereas glucose during the day or with food ingestion.

The animations below should be viewed in the order in which they appear for best understanding. Please view the glossary at the bottom of this page for definition of relevant biochemical terms.

1

FAT MOBILIZATION

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In the tissues:

ATGL adipose triglyceride lipase; HSL hormone-sensitive lipase; MAGL monoacylglyerol lipase; FFA free fatty acid; TAG triacylglyer-ide/-ol; FABP fatty acid binding protein; FATP fatty acid transport protein.

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2

FAT STORAGE

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In the tissues:

ATGL adipose triglyceride lipase; HSL hormone-sensitive lipase; MAGL monoacylglyerol lipase; FFA free fatty acid; TAG triacylglyer-ide/-ol; FABP fatty acid binding protein; FATP fatty acid transport protein; GLUT glucose transporter.

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The major fuel store of the body is triglyceride or TAG in adipose tissue. Glycogen in liver and muscle is more of a short-term store of carbohydrates. From the above animations, we can see how these molecules play an interconnected role to provide energy or be stored at different times. But during metabolic diseases like diabetes or obesity these processes do not occur optimally.

 

3

DIABETES

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CHYLOMICRONS: are large triglyceride-rich lipoproteins produced in enterocytes or intestinal cells from dietary lipids like fatty acids and cholesterol.

ESTERIFICATION: is the process of formation of an ester by the combination of an organic acid with an alcohol. An example is formation of triglycerides from fatty acids and glycerol.

FATTY ACIDS: are building blocks of lipid molecules such as fats. They can be obtained both through diet or breakdown of stored fats in the body.

GLUCONEOGENESIS: is the process of conversion of non-carbohydrates such as lactate, glycerol and amino acids into glucose.

LIPOLYSIS: is a term for the breakdown of lipids

LIPOPROTEINS: Cholesterol and triglycerides are important lipids in the body. They are insoluble in water and therefore transported in complex particles called lipoproteins.

TRIGLYCERIDES or TRIGLYCEROLS: are chemicals formed by the combination of fatty acids and glycerol (an alcohol).

VLDL or VERY LOW DENSITY LIPOPROTEINS: are lipoprotein particles secreted by the liver into the blood. The excess fatty acids and cholesterol in the liver are converted to their respective esters and packaged with proteins into VLDL.

CREATORS

This lesson was designed by Shraddha Nayak, a postdoctoral fellow in the Animation Lab at the University of Utah with guidance from lab members and its head, Janet Iwasa. It was created in collaboration with biochemists and educators, Janet Lindsley and Amy Hawkins from the University of Utah, and Judith Simcox from the University of Wisconsin-Madison. We thank the Diabetes and Metabolism Research Center (DMRC) at the University of Utah and its donors for funding this project.

TERMS OF USE

This work falls under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

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