Fat.

Good fat, bad fat. Good cholesterol and bad cholesterol. Full fat. Low fat. Non-fat. Some people say eating fat will make you gain weight; others say it can help you lose weight. It can be hard to keep all of it straight!

What does all of it really mean for you?

When people say good fat and bad fat, they may be referring to two different things.

The first, and most common, is the notion of dietary fat that we should or should not eat. Good fat can increase our good cholesterol, HDL (high-density lipoproteins), and bad fat can increase our bad cholesterol, LDL (low-density lipoproteins). High levels of HDL can protect against heart disease, whereas high levels of LDL can cause plaques to form, leading to atherosclerosis and potentially heart attacks and strokes.

In our MyPlate Monday Series, we talked a little about the importance of including good fats in your diet. Healthy fats include omega-3s, found in fish and flax seeds, along with monounsaturated fats, such as those found in olives, nuts, and seeds. Mediterranean diets often include many of these good fats.

Unhealthy fats are primarily saturated fats and trans fatty acids. Saturated fats are found in animal products such as milk and meat, and oils that are solid at room temperature, including coconut oil and palm oil. This is where you should strive for low-fat and non-fat milk, yogurt, and cheeses. But when it comes to sweets and desserts, stick with full-fat and small portions. Since much of the flavor comes from the fat, eating fat-free cookies or ice cream can leave you unsatisfied and ultimately cause you to eat more. Also, processed foods that advertise as fat-free often add other unhealthy ingredients to cover up for the lack of taste.

The second type of good fat and bad fat are the fat cells in our bodies. Scientifically they are known as brown adipose tissue (good fat) and white adipose tissue (bad fat). Brown or good fat is made up of special cells that burn calories in order to keep the body warm. White or bad fat constitutes the majority of fat in adults and is a major contributor to negative health outcomes related to obesity.

For ages, it was understood that only infants had significant amounts of brown fat, but some recent studies have found that adults carry more brown fat than previously thought. Young women in particular have a significant amount of good brown fat, especially in comparison to older men, who have very little. While you can’t control your ratio of white to brown fat, scientists are currently working on ways to utilize this good fat in adults to treat obesity. Last year, a study found that a particular hormone in the brain can activate brown fat. And just this past week, a team published their study on a protein that may impact the ratio of white to brown fat.

So the ultimate takeaway: eat foods with healthy fats (fish, nuts, olives), avoid foods with saturated or trans fats (full-fat milk, coconut oil), and don’t fall for processed foods with fat-free labels.

Sources: American Heart Association, WebMD, LiveStrong