When we think about fat, we often think of something we should avoid—either in our food or on our bodies. But not all fats are bad.
In fact, some fats are necessary for our health. Alice H. Lichtenstein, a leading nutrition expert at Tufts University, explains why fats are important and how we can make smart choices about the kinds of fat we eat.
Fats in food are mostly in the form of triglycerides. These are made of three fatty acids joined to a small molecule called glycerol. When we eat food with fat, our bodies break down the triglycerides into individual fatty acids.
These fatty acids then travel through the blood to cells where they are used for energy or other important jobs. If we eat more calories than we need—whether from fat, protein, or carbs—our bodies store the extra energy as body fat.
Fats are vital for life. In plants, fats in seeds provide energy for new growth. In people and animals, fats help build cell membranes and make hormones. Fat just under our skin helps control body temperature. Fats also give us a steady supply of energy, and they make food taste good. They also help our bodies absorb vitamins A, D, E, and K.
So, is eating fat bad for us? The answer isn’t simple. Fat has more calories per gram than protein or carbs. This means we can eat a lot of calories quickly if we eat too much fat. However, studies show that total fat intake doesn’t always relate directly to body weight. It’s more about how many total calories we eat.
Some people worry about fats raising their blood triglyceride levels, which can increase the risk of heart disease. But high triglyceride levels are more often caused by diets high in sugar and low in fat. That’s because the liver turns excess sugar into fat, which then increases triglyceride levels in the blood.
It’s also important to understand that not all fats are the same. Fatty acids—the building blocks of fats—come in different types. Some are saturated, meaning they are full of hydrogen atoms.
These are usually solid at room temperature and found in animal products like meat and dairy. Others are unsaturated, which means they have fewer hydrogen atoms. These are usually liquid and found in plants and fish.
Unsaturated fats are considered healthier. They come in two main types: monounsaturated and polyunsaturated. Oils like olive and canola are high in monounsaturated fats.
Soybean and corn oil are high in polyunsaturated fats. Some polyunsaturated fats, like omega-3 and omega-6, are essential—our bodies can’t make them, so we need to get them from food.
Eating less saturated fat and more unsaturated fat can help protect our hearts. This means eating more nuts, seeds, and plant oils, and less meat and full-fat dairy. Some people worry that omega-6 fats cause inflammation, but research shows they are safe and even beneficial when eaten in normal amounts.
Fish is a great source of omega-3 fats, which are linked to a lower risk of heart disease. Plant-based omega-3s, like those in soybean and canola oil, are also good, though our bodies don’t convert them as well as the fats in fish.
So how do we get the right balance? Choose fats that come from plants and fish, not from animals. Use oils like olive and canola instead of butter and lard. Eat more fish, beans, and low-fat dairy, and cut back on red meat and full-fat cheese.
By making these small changes, you can enjoy the benefits of healthy fats without overdoing it. Fats aren’t the enemy—they’re an important part of a balanced, healthy diet.
If you care about nutrition, please read studies about berry that can prevent cancer, diabetes, and obesity, and the harm of vitamin D deficiency you need to know.
For more health information, please see recent studies about the connection between potatoes and high blood pressure, and results showing why turmeric is a health game-changer.
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