Today I’m talking about fats, one of the macronutrients. Protein, fat, and carbohydrate are the three major macronutrients in the diet. Water is sometimes included as a fourth macronutrient.

But first, I’d like to begin with a few words on carbs: The term carbohydrates refers to carbohydrate that comes from a plant that grows in the soil. Whether leaf or fruit or root or stem, this kind of carbohydrate is always, always rich in fiber and phytonutrients. Except for milk and honey, carbohydrate doesn’t really exist in nature without the fiber. This means that whenever you come across carbohydrate without fiber attached, humans probably made it that way. But we don’t call whole, or fiber-rich, carbohydrates “healthy carbohydrates.” In a blog about good health and nutrition, you can assume that I’m always talking about the healthy kind. And while it is true that we, as a society, are drowning in stripped, “unhealthy,” carbs, people do not feel the need to keep reminding themselves. 

So why the term “healthy fats?” I can think of a couple of reasons. The first one is that we have been influenced by the advertising and manufactured-calories industries to be suspicious of the fat in a nourishing diet. We have been told, over and over, that if you eat fat you’ll get fat. And we have internalized this message so successfully that people can sometimes be seen to wrinkle their noses or even stick out their tongues on hearing the word “fat.”

Yet it turns out that this message does not serve us well. Once upon a time, before the development of insulin, a high-fat diet was the only treatment available for diabetes. As a young physician, I noticed that the less fat my patients ate, and the more stripped carbohydrate they were taught to substitute, the more overweight they became. When I shared my observations with them, they were dumbfounded. America does truly have an enormous weight problem. But it’s not because of fat as a general category. If I were going to be more specific, I’d say it’s because of the large amounts of industrially modified fat that Americans are eating.

When I first began to practice medicine in the mid 1990s, fats were still being vilified, and people were still being encouraged to limit their fat intake as much as possible. This many years later, we have come to understand that certain fats are particularly nourishing, and we now encourage patients to eat foods like olives and olive oil, avocados, nuts and nut butters, seeds (e.g., sunflower, chia, flax, hemp), peanuts, tahini, salmon, and deep-sea fish. There may be more, and I am going to predict that this list will continue to lengthen as our understanding expands, but for now these are ones that most of us can agree on. 

The fats to avoid are those that were invented in the twentieth century. Those are manufactured calories. Manufactured calories are not food and they do not nourish you.

In order to distinguish nourishing fats from the fats that were invented in the 20th century, and which were not previously a part of the human diet, we began to call nourishing fats “healthy,” as if the fats themselves are healthy. But they’re not. They are chemical compounds that break down into various fatty acids of various configurations that happen to serve one or another of the beneficial purposes for which we consume them. 

Do we finally know everything we need to know, everything we’re ever going to need to know, about nutrition and fats? It would be premature to think so. But there are some important conclusions on which we can all agree. And one of them is that nourishing fats play an important role in our diets.