A Guide to Fats

Learn about the different types of fats and which you should avoid.

In This Article:

Fats and fatty acids

Once upon a time, we didn't know anything about fat except that it made foods tastier. We cooked our food in lard or shortening. We spread butter on our breakfast toast and plopped sour cream on our baked potatoes. Farmers bred their animals to produce milk with high butterfat content and meat “marbled” with fat because that was what most people wanted to eat.

But ever since word got out that diets high in fat are related to heart disease, things have become more complicated.

Fats and Fatty Acids

Fats are a group of chemical compounds that contain fatty acids. Energy is stored in the body mostly in the form of fat. Fat is needed in the diet to supply essential fatty acids, substances essential for growth but not produced by the body itself.

There are three main types of fatty acids: saturated, monounsaturated and polyunsaturated. All fatty acids are molecules composed mostly of carbon and hydrogen atoms. A saturated fatty acid has the maximum possible number of hydrogen atoms attached to every carbon atom. It is therefore said to be “saturated” with hydrogen atoms.

Some fatty acids are missing one pair of hydrogen atoms in the middle of the molecule. This gap is called an “unsaturation” and the fatty acid is said to be “monounsaturated” because it has one gap. Fatty acids that are missing more than one pair of hydrogen atoms are called “polyunsaturated.”

Saturated fatty acids are mostly found in foods of animal origin. Monounsaturated and polyunsaturated fatty acids are mostly found in foods of plant origin and some seafoods. Polyunsaturated fatty acids are of two kinds, omega-3 or omega-6. Scientists tell them apart by where in the molecule the “unsaturations,” or missing hydrogen atoms, occur.

Recently a new term has been added to the fat lexicon: trans fatty acids. These are byproducts of partial hydrogenation, a process in which some of the missing hydrogen atoms are put back into polyunsaturated fats.

Polyunsaturated and monounsaturated fats do not promote the formation of artery-clogging fatty deposits the way saturated fats do.

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