Fats have been given a bad reputation. What are fats and why do we need them?

Fats are probably the most interesting macromolecules in food because there are so many different types of fats. Unfortunately, food fats have been given a bad reputation, in part because body fat is the way we store excess calories, and, in part because certain food fats, including saturated fats, trans-fatty acids, and cholesterol, have been associated with health conditions like cardiovascular disease and obesity.

The facts, however, are different. Not only are food fats not always bad, but some food fats have been shown to be health-promoting, and some food fats are absolutely essential for your health. So, when you think about food fats, the quality of the fat, and therefore the quality of the food from which you are getting the fat, really matters.

Within the unsaturated fats, there are two basic kinds, called monounsaturated and polyunsaturated. Monounsaturated fats, like those found in olive oil, are usually liquid at room temperature but will form solids in the refrigerator. That’s why you’ll find an oil like olive oil, which is about 70% monounsaturated, becoming thicker, less clear, and more difficult to pour when placed in the refrigerator. Polyunsaturated fats tend to stay liquid regardless of temperature. That’s why you’ll find highly polyunsaturated plant oils, like sunflower oil, or soybean oil, or flaxseed oil, remaining liquid at both room and refrigerator temperatures.

All types of fat are needed by the body, including saturated fat, monounsaturated fat, and polyunsaturated fat. These fats also serve a wide variety of different purposes. All of our cell membranes contain fat in their chemical composition, and many of our cells can also burn fat as an energy-providing fuel. Fats also store and carry nutrients around the body, provide physical insulation for body organs, help maintain body temperatures, and play a wide variety of different roles in metabolism. These are some of the reasons that the fats found in food are essential to health.