Fat is one of your body’s major nutrients. In fact, it’s one of three macronutrients. Not only is there some fat in most healthy foods, but there’s fat in very important parts of you.

1. Your brain is mostly fat (and water).
2. Fat is the key building block of hormones including estrogen and testosterone. (Estrogen and testosterone are mandatory for both women and men.)
3. Your body needs fat to absorb several key vitamins: vitamin A, vitamin D, vitamin E, and vitamin K. No fat, no vitamin ADEK.

For decades, we’ve given fat such a bad rap, but it’s not all negative.

You have body fat. It’s normal! And you need it. Actually, it’s important for you to be sure you have enough body fat. If you don’t, those three little things I mentioned above? … They won’t work properly. (You can scroll up but your brain was one of those things!)

But you also eat fat. Let’s call it dietary fat. And not all dietary fat is created equally.

First, there are unsaturated fats. And among unsaturated fats,...