“Fats are bad for you.”
“Eating fat will make you gain weight.”
“You don’t actually need fat in your diet.”
Fats have been in the headlines for years. Although they’re more accepted now than they were during the low-fat diet craze in the 1980s and 1990s, fats still don’t always get the love they deserve. Get the skinny on fats so you’re ready to stop nutrition misinformation in its tracks.
Does your body need fat?
Dietary fats help you feel satisfied with a meal, and they’re a rich source of energy for your body. While carbohydrates and proteins provide four calories per gram, fats provide nine calories per gram.
But wait – more calories? Isn’t that bad?
No, not necessarily.
Calories aren’t inherently bad – they’re just a unit of energy. The number of calories in a food determines how much energy your body can get from eating that food. Everyone has different calorie needs based on their height, weight, and activity level, so talk with a local registered dietitian to determine a calorie level that’s appropriate for you.
Fats also play a role in several essential functions within the body. They support healthy cell function, help your body absorb certain nutrients, protect your organs, and help produce important hormones.
Are there different kinds of fats?
Like everything on Earth, dietary fats are made of atoms. More specifically, they’re made up of chains of carbon atoms connected to hydrogen atoms. There are four major types of dietary fats – each with different chemical structures that affect the way they work in the body. Take yourself back to chemistry class for a moment to discover how their slight differences make each fat unique, and how they impact your health.
1. Saturated fat
Saturated fats contain no double bonds (only single bonds) in their fatty acid chains, so they’re “saturated” with hydrogen atoms. Saturated fatty acid chains are arranged in a straight line, so they’re able to stack together tightly. That’s why they’re usually solid at room temperature – think butter, lard, and some tropical oils. Saturated fat is also found in animal products like meat, cheese, and milk.
Too much of this type of fat may cause problems with your cholesterol levels and increase your risk for other heart conditions.
2. Monounsaturated fat
Monounsaturated fats contain one double bond in their fatty acid chain. Because of this, they’re not “saturated” with hydrogen atoms. The arrangement of hydrogen atoms around the double bond also causes a slight bend in the fatty acid chain, so they can’t stack as tightly together as saturated fats. That’s why unsaturated fats are usually liquid at room temperature – think plant-derived oils like olive, canola, and peanut oil. Avocados, nuts, and seeds are also rich sources of monounsaturated fats.
3. Polyunsaturated fat
Polyunsaturated fats are very similar to monounsaturated fats, but instead of just one double bond in the fatty acid chain, polyunsaturated fats have two or more. Polyunsaturated fats are also liquid at room temperature. You’ll find higher levels of this type of fat in sunflower oil, corn oil, flaxseeds, walnuts, and fatty fish like salmon, mackerel, tuna, or herring.
4. Trans fat
Trans fats exist naturally in very small amounts in some meats and dairy products, but the majority are created artificially by adding hydrogen atoms to vegetable oils to make them more solid. This process is called partial hydrogenation, and it helps extend the shelf life of food products and prevent them from going rancid.
But research has shown that these artificially made fats are harmful to your health. In fact, they can increase your LDL (bad) cholesterol and decrease your HDL (good) cholesterol. The FDA banned artificial trans fats, and most of them have been removed from the food supply. However, they may still be lurking in some packaged snacks, baked goods, fast food, and some vegetable shortenings and margarine.
Which types of fat should you include in your diet?
Some types of fat are better for your health than others. Aim to avoid trans fats, limit saturated fats, and replace them with unsaturated fats.
Avoid: trans fats
The negative health effects of trans fats have been well-documented, so it’s best to avoid trans fats altogether. Although trans fats have been phased out of most foods, it’s still important to check the food label carefully. Nutrition labels can be tricky – a food can have up to 0.5 grams of trans fat per serving and still show 0 grams on the nutrition facts label. Double-check the ingredients list for partially hydrogenated oils – that’s an indicator the product still contains trans fats, even if the label says 0 grams.
Limit: saturated fats
While the relationship between saturated fat and heart health is still widely debated, the 2020-2025 Dietary Guidelines for Americans still recommends limiting saturated fat to 10% of your total calories. That’s about 22 grams of saturated fat based on a 2,000 calorie diet – but remember, you may have different calorie requirements.
Replace with: unsaturated fats
Limiting saturated fat is just one piece of the puzzle. The key to heart health is replacing those saturated fats with poly- and monounsaturated fats.
Here are a few smart swaps to get you started:
- Cook with olive or avocado oil instead of butter.
- Replace meat with plant-based protein, like beans, lentils, nuts, seeds, or tofu, at least once per week.
- Choose heart-healthy snacks, like nuts and low-fat yogurt, peanut butter and an apple, or carrot sticks and hummus instead of packaged snacks, such as cookies or chips.
All fats aren’t bad for you. Eating fat won’t make you gain weight. And you actually do need fat in your diet. Bottom line: fats aren’t the enemy. Include healthy fats in your diet confidently, knowing that you’re supporting so many essential functions within your body – nutrient absorption, hormone production, healthy cell function, and more.