Everything you ever wanted to know about fat – and more!

What is the difference between oils, fats, and lipids?

Fat = oil = lipid

“Lipid” is the general term for all fats and oils. Originally, “fat” referred to lipids that are solid, and “oil” referred to lipids that are liquid, at room temperature.[1] This is less important now that we know the chemical structure of the molecules, so we can use them interchangeably. And to be clear, we are only talking about life, NOT about the mineral oils that come from petroleum.

EFA – Essential fatty acids, which are like vitamins, are required for life, and we must eat them because we can’t make them. These include omega 3 and omega 6 PUFA.

PUFA – Polyunsaturated fatty acids are long-chain fatty acids that have multiple  double bonds. They are made by plants and include omega-3 and omega-6 EFA.

These are also called: HUFA – highly unsaturated fatty acids.

What are lipids?

Lipids are long chains of carbon atoms that have no polarity, so they do not dissolve in water. In the body, they generally have a molecule at one end that is water soluble, allowing them to function. For example, our cell membranes are made of
fats called phospholipids. 

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Because blood and body fluids are water-based, the “hydrophobic tails” of the oil isa long chain of carbons that reject water stick together, and their “hydrophilic heads” that are attracted to water stay on the outside. These “heads” are phosphate, which attracts water. Thus, there can be water-based fluid on both sides, creating a membrane barrier between the inside and outside of cells.

What are fatty acids?

These are just lipids with long chains of carbons, that have an acid (carboxyl) group on one end of the chain – where the phosphate would be in the phospholipids. The fatty acid is the basic building block of oils in the body and is converted for various
uses, such as phospholipid membranes, leukotrienes, or hormones.

What are saturated and unsaturated fats?

There are two main kinds of oils used in cell membranes and in the body:

1. Saturated

2. Unsaturated

Your body makes saturated fats or eaten as animal fats, butter, or coconut oil. They are generally solid at room temperature. Saturated fats have a long chain of carbons that are all filled with hydrogen atoms, making them strait so they stick together easily, that’s why they’re solid. Saturated fat is not the enemy it has been made out to be. The problems that are seen with coronary artery disease are not related to saturated fat.[2] Heart disease comes from inflammation, and clots in the arteries, caused, in part, by omega-6 and partially-hydrogenated oils with trans-fats. Feel free to eat saturated fat.

Unsaturated fats come from plants, such as corn, soy, or flaxseed oil, and are called PUFAs (Poly-Unsaturated Fatty Acids). Olive oil and canola oil are primarily “monounsaturated” having only one double-bond. Unsaturated means there are places in the chain where there is only one hydrogen on the carbon, making a double bond between the two carbon atoms. Plants make unsaturated fats. We can get them from fish, but the fish get them from algae and plankton. If chicken, pork, and beef have omega 3 or 6, they get it from eating plants. The unsaturated fats are irregular, so they are more liquid.

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The carbon with the carboxyl group (where you see the “HO-”) is the first carbon atom, and the “omega” carbon is the last one. Thus, “omega-3” means the first double bond is on the third carbon from the omega end. Omega 6 has the first double bond on the sixth carbon from the omega end, as in the “Unsaturated fatty acid” illustration above (which is a mono-unsaturated fatty acid).

What are triglycerides?

When these fatty acids are bound together in groups of three by a three-carbon alcohol called glycerol, they are called triglycerides.[3]

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Triglycerides are the storage form of fat. This is the fat that is in your fat cells. It contains both saturated and unsaturated fatty acids, depending on the diet and genetic factors. If the fat is made in your body, it is mostly saturated fatty acids, with a small amount of monounsaturated fats. If you have a diet high in PUFA, these will be attached to a glycerol molecule and stored in your fat cells as well.

What is rancid oil?

PUFA omega 3 and omega 6 oils can oxidize and become rancid. This mostly affects the flavor of food, but the oxidized oils also act as immune modulators, causing inflammation.

It is interesting to look at the PUFA content of foods to see which are stable. For example, in the chart below, look at both safflower oil and coconut oil. They are both stable because they have very little PUFAs and can be heated. But both soybean and flaxseed oil are not suitable for frying because they oxidize easily when heated. This is why scientists developed hydrogenated oils. This is also the reason to make sure your oils are “cold-pressed” and not heated during processing.

What are hydrogenated oils and “trans-fats?”

PUFAs are cheap, but they are liquid and oxidize easily so they don’t last long, causing food to spoil. Because saturated fats work better for baking, cooking, and preserving food, but animal fat is expensive, chemists devised a way to “saturate” the unsaturated fats with hydrogen. This made saturated fats plentiful, but also added the problem of “trans-fats.” During the chemical reaction, some get a configuration called “trans-fat” the body cannot use it. It becomes toxic, the fat cells store the trans-fat and membranes use it. This can lead to inflammation, heart disease, and cancer.[4]

Why are the omega PUFAs so important?

The “omega” oils are essential for life but our body cannot make them – we must eat them. What’s more, how much of each we eat determines how the body functions. We need them to make hormones and membranes. Without PUFAs we cannot make a single cell. For example, the DHA (omega 3) fat in the brain membranes makes them more fluid and allows signals to get into the brain cells. Without DHA the brain cannot function. Also, without the cell signaling of the omega 6 oils, we would not be able to activate the immune system and would die of infection.

What is the difference between omega 3, 6 and 9?

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