Start Here: The Basics

Before the families, the metabolism and the health debates, it helps to get the vocabulary and the shapes straight. Fat is the everyday word for the greasy stuff in food and in the body; a fatty acid is the smaller molecule that fat is built from. Almost all the fat you eat and store is packaged as triglycerides — three fatty acids tied to a glycerol backbone — so a fatty acid is best thought of as the basic building block, the way a letter is to a word.

This section builds that foundation one step at a time: how fat compares with the other two macronutrients, carbohydrate and protein; the simple anatomy of a fatty acid — a water-loving "head" and a long water-hating "tail"; the single most useful distinction, saturated versus unsaturated; why chain length matters; and finally how to read the shorthand names like C18:1 n-9 that appear throughout the rest of the site. Work through them in order and the later sections read much more easily.