Prev NEXT  

Advertisement

How Fats Work

Essential Fatty Acids

The most common fatty acids are found in animal fats and include:

  • Palmitic acid
  • Stearic acid
  • Oleic acid

Your body is able to create these fats whenever it has a caloric surplus. It can create them from straight sugar if there are enough sugar calories coming in (see How Food Works for a discussion of carbohydrates and sugar).

Advertisement

It turns out that there is another class of fatty acids called essential fatty acids that your body cannot manufacture. These fatty acids include:

  • Linoleic acid (LA) (omega-6)
  • Arachidonic acid (AA) (omega-6)
  • Gamma linolenic acid (GLA) (omega-6)
  • Dihomogamma linolenic acid (DGLA) (omega-6)
  • Alpha linolenic acid (LNA) (omega-3)
  • Eicosapentaenoic acid (EPA) (omega-3)
  • Docosahexaenoic acid (DHA) (omega-3)

Because your body cannot manufacture them, they must come in from the food you eat.

Essential fatty acids fall into two groups: omega-3 and omega-6. The 3 and 6 refer to the first carbon double bond position on the fatty acid chain. All essential fatty acids are polyunsaturated, so the 3 and the 6 mean that the first double bond is either 3 or 6 carbons in from the end.

Omega-6 fatty acids are everywhere: corn oil, sunflower oil and soybean oil all contain them. Omega-3 fatty acids are harder to find. Things like flax seeds, pumpkin seeds and walnuts are high in omega-3 fatty acids, as are salmon, trout and tuna. Current thinking is that these two fats need to be balanced in the diet at a ratio like 1-to-1 or 2-to-1, rather than the normal 20-to-1 ratio seen in most Western diets. About the only way to do that is to supplement your diet with omega-3 vegetable oils or to start eating fish in a big way (meaning two or three times a week).

Summarizing all of this information, the current scientific thinking on fat consumption goes something like this:

  • Limit your fat intake to about 30 percent of the total calories you consume. Do not try to cut fat intake altogether, because you do need the essential fatty acids. A gram of fat has nine calories, meaning that if you consume 2,000 calories in a day your total fat intake should hover around (2000 * 30 percent / 9 calories/gram) 67 grams of fat.
  • When consuming fat, try to focus on mono-unsaturated fats like olive oil and canola oil, or on essential fatty acids.
  • When consuming essential fatty acids, try to balance your intake of omega-6 and omega-3 fatty acids. Do that by consuming tuna/salmon/trout or omega-3 oils like flax seed oil.

For more information on fats, nutrition and related topics, check out the links below.

Related HowStuffWorks Articles

More Great Links

Advertisement

Advertisement

Advertisement

Advertisement

Advertisement

Advertisement


Advertisement


Recommended

Advertisement

Advertisement