For years, the common knowledge was that fat makes you fat. Any food high in fat should be avoided and replaced with a low-fat choice. In theory, this sounds reasonable. If something contains a lot of fat, it must cause you to gain weight, right?
Researchers in the 1970s believed this and started urging people to adopt low-fat or fat-free diets. Eventually, the public was convinced that fat was the enemy, and weight-loss diets low in all types of fatty foods became the norm.
But it’s not that simple. Back then, scientists were unable to make the distinction between different types of fat. So they simply concluded that all fats were bad and left it at that. Today, though, we know of the existence of multiple types of fats: saturated fats, monounsaturated fats, polyunsaturated fats, and trans fats. Not all of them cause weight gain, and some are even healthy. So which ones should you include in your diet and which ones should you avoid?
First, let’s start with unsaturated fats–a type of fat considered to be healthy. The term “unsaturated fats” generally includes both monounsaturated and polyunsaturated fats, both of which are essentially the same thing. Unsaturated fats can be found mostly in plant-based foods, such as olive oil, peanut oil, canola oil, avocados, and various nuts, as well as fatty fish like salmon, sardines, and herring. They should be included in your diet as much as possible, because they provide many benefits over other types of fats. In fact, research shows that replacing saturated fats with unsaturated fats can have the same effect on your heart health as cholesterol-lowering medications.
One type of fat you want to be careful around is saturated fat, which is found in red meat, cheese, and whole milk. Research on saturated fat is limited, and scientists aren’t exactly sure how it influences the body. Most recommend to keep your saturated fat intake to a minimum, just to be safe. But don’t be afraid to have a glass of milk or a steak every now and then.
The last type of fat, which should be avoided entirely, is called trans fat. Trans fats are a mainly artificial substance and raise your risk of heart disease, diabetes, and stroke. Once, they were common in pre-packaged baked goods and other processed foods, but today they’re completely outlawed. The FDA considers them “not safe for human consumption” and has taken steps to completely remove them from the food supply. If there’s any fat you shouldn’t go near, it’s trans fat.
Based on what we know today, the bottom line is that unsaturated fats are good for you, saturated fats should be consumed in moderation, and trans fats should be cut out from your diet completely. As research on the topic progresses, we’ll know more about the different types of fats and how they affect the body in the years to come.