Fat is the bane of many diets, but it’s an essential macronutrient—it’s no less than the protein we need to eat. It plays a variety of functions in the body. It’s a source of energy alongside the glucose we get from carbohydrates. Fats help us absorb the vitamins we take and allow our cells to communicate with each other. And, yes, they help food taste good, too.
“If you appreciate the smoothness of guacamole or the flakiness of a croissant, you have dietary fats to thank,” says Ali Webster, a registered dietitian and senior director of research and nutrition communications at the International Food Information Council.
Naturally, like other elements to a complete diet, fats should be enjoyed in moderation. That’s because fats are also high in calories: every gram of fat contains nine calories, while every gram of protein or carb you eat contains only four. For that reason alone, fats can be detrimental for maintaining a healthy weight and heart. But they’re in lots of the foods we’re all eating: meat, fish, milk, and more. So let’s chew the fat, and break down what’s important to know.
Cut the Fat
There are two types of dietary fats, both of which are composed of long, straight chains of carbon atoms, with a varying number of hydrogen atoms running along the length of the chain. Saturated fats are called that because they have more hydrogen atoms—which also means they’re solid at room temperature. Unsaturated fats have fewer hydrogen atoms, and are usually in liquid at room temperature.
Saturated fats are found in animal foods, like chicken and beef, as well as in the types of foods everyone loves to eat: pizza, foods, desserts, and drive-thru cheeseburgers. These are the fats that can lead to higher levels of LDL, or low-density lipoprotein. As you know from GQ‘s primer on cholesterol, LDL is the bad stuff, too much of which can clog up our blood vessels and make it difficult for the body to adequately move oxygen around. The Dietary Guidelines for Americans recommend a saturated fat intake of less than 10% of someone’s daily calories. The American Heart Association goes a little further: No more than 6% of your daily calories should come from saturated fats.
Not That Kind of Poly
The real problem, with fat, is that people don’t eat enough unsaturated fats, at least according to the Harvard School of Public Health. Unsaturated fats are broken into two groups: monounsaturated and polyunsaturated. Avocados, almonds, and olive oil contain monounsaturated fats; salmon, walnuts, and canola oil contain polyunsaturated fats.
As Webster points out, there are observational studies that indicate replacing saturated fats with monounsaturated fats can lead to a better balance of LDL and HDL—high-density lipoprotein, or the good cholesterol—and therefore improve the function of blood vessels in the body. Better function means better cardiovascular health. Meanwhile, polyunsaturated fats help to reduce the total amount of LDL cholesterol, thanks to their concentrations of omega-3 and omega-6 fatty acids.