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Why is Fat in Your Diet Important?

Reading Time: 5 minutes 10 seconds


Date: 2022-05-04

Dietary fat got an unfair and negative reputation during the low-fat, fat-free diet craze years ago. For people who lived through it, it’s still challenging to recognize fat’s dietary importance and embrace it. 

Fat is one of three essential macronutrients. Your body needs it to function normally and for optimal health. Learn more about why you need fat and the types to prioritize. 

Why People Are Squeamish About Dietary Fat

There are a couple of reasons why many people still have a hard time accepting the need for fat in the diet. One is simply the energy density. One gram of fat provides nine calories compared to the four you get from a gram of carbohydrates or protein. If you are weight conscious, you might hesitate to consume adequate fat because of the calorie count. 

Another issue is simply confusion. Health experts have warned for years about the connection between eating too much saturated fat and an increased risk for cardiovascular disease. 

These warnings led to a low-fat diet craze, but the problem was that many people replaced fat with carbs. Research shows that dropping fat and adding carbs has no benefit to cardiovascular health. What does help is to replace saturated fat with more plant-based unsaturated fat. 

Better information and education about dietary fats can clear up this misinformation and confusion. While you might want to reduce fat intake a little when trying to lose weight, it’s better for overall health to focus on consuming an adequate amount of the so-called healthy fats. 

Why is Fat in Your Diet Important, Even Essential? 

Fat is an essential nutrient. You need an adequate amount of all of the macronutrients—fat, carbohydrates, protein—to be healthy and function normally. These are just some of the many reasons you must consume fat in adequate amounts for optimal health. 

Cells Need Fat

Normal cell growth and repair require fat. Fatty acids make up the membrane that surrounds every cell in the body. For cell types that continue to grow and divide as you age, like red blood cells, fat is a requirement. Your skin cells weaken when you don’t have enough fat, causing dry, itchy, and irritated skin. 

Fat is an Important Source of Energy

Your body uses glucose first for energy, but when that runs low, it needs fat to keep going. This is especially important for people who are active. During a tough workout, you’ll get fatigued and need to quit early if you don’t consume adequate fat. 

Healthy Fats Support Brain Health

Omega-3 fatty acids, in particular, are essential in the diet for brain health. Your body cannot make these fats, so you must take them in through foods or supplements. They play a big role in the functioning of the central nervous system and the retinas in the eyes. 

You Need Fat to Absorb Vitamins

The fat-soluble vitamins—A, D, E, and K—require fat for absorption. Your body cannot use these essential nutrients if you consume them with no fat. Vitamin deficiencies cause a range of health problems. 

Poor nutrient absorption can occur even in people who eat well. Know the signs and see a doctor if you aren’t absorbing nutrients. 

Fats Are the Basis of Hormones

Fat molecules are necessary to produce some hormones, including estrogen and testosterone. If you’re not consuming enough fat, it can lead to unhealthy hormone imbalances. 

Why is Fat in Your Diet Important Even When Trying to Lose Weight? 

Regardless of where you are on a weight loss journey, you need fat in your diet, especially healthy fat. You might want to reduce fat a little bit because it does provide a lot of calories, but don’t go overboard. In addition to the normal functioning that fats support, dietary fat can also be beneficial to your diet goals. 

Fat plays a big role in satiety. It helps you feel full and satisfied. Without adequate fat, you risk feeling hungry and overeating. Furthermore, fat in foods minimizes the blood sugar spike you might otherwise get. A drastic blood sugar increase leads to a later crash that causes many people to overeat. 

Check out the best foods for regulating and maintaining healthy blood sugar levels. 

Signs You Might Be Eating Too Little Fat

Fat deficiency is pretty rare, especially in the western diet, but it does happen. People at risk for it include those with eating disorders, inflammatory bowel disease, cystic fibrosis, and certain other health conditions. 

Even without any of the above, you might be getting deficient if trying to eat a very low-fat diet. These are some signs you might not be taking in enough fat:

  • Irritated and inflamed skin

  • Slow healing wounds

  • Hair thinning and loss

  • Getting sick more often

Too little fat can also lead to vitamin A, D, E, or K deficiencies, which cause night blindness, easy bruising, dry hair, loose teeth, muscle pain, bleeding under the nails, and swollen gums.

Types of Dietary Fat

As important as amount of fat, if not more, is the type of fats you consume. There are three main categories: 

  • Unsaturated fats. The bulk of your fat intake should be in the form of unsaturated fats, which come from plants and some fish. Monounsaturated fat is found in most seeds and nuts, avocados, and olive oil. Polyunsaturated fat is found in fatty fish, walnuts, sunflower seeds, flax seeds, vegetable oil, and fatty fish. This latter category includes omega-3 fatty acids.

  • Saturated fats. Saturated fats mostly come from animal sources, especially beef, pork, and full-fat dairy products. Plant sources include coconut and palm oils. It’s fine to eat some of these, but it should be minimal. 

  • Trans fats. Trans fats are unsaturated fats that have been hydrogenated, or chemically altered, to be solid at room temperature. Unsaturated fats are naturally liquid, and they have a shorter shelf life. Trans fats raise bad cholesterol and lower good cholesterol levels. They are strongly associated with heart disease, stroke, and type 2 diabetes. 

The best way to include fats in your diet is to put most of the emphasis on unsaturated fats. Use healthy cooking oils and butter substitutes; snack on nuts and seeds; and enjoy fatty, oily fish like salmon or mackerel a few times per week. 

Indulge in saturated fats sparingly and completely avoid trans fats. Thanks to regulations, trans fat is now rare in American foods. Read food labels carefully, though. Many packaged foods with long shelf lives still have a little bit of trans fats in them. 

The nutrition information might say zero grams, but this includes anything between zero and 0.5 grams. If the ingredient list has the words hydrogenated or partially hydrogenated, put it back. 

How Much Dietary Fat is Healthy? 

The current government recommendation for fat intake is between 20% and 35% of your daily calories. For someone eating about 2,000 calories per day, this amounts to 44 to 77 grams. Saturated fat should make up less than 10% of daily calories (about 22 grams), and you should avoid all trans fats. 

The low end of the range—20%—is pretty low. A number closer to 30% is better for most people. When you begin to drop below 20% in the diet, you might begin to experience some negative side effects. 

Fat is a difficult hurdle for some people to get over. Help your clients by educating them about the role of dietary fat in good health. With correct information and resources for choosing healthier foods, they will be closer to their goals. 

Nutrition information can be confusing, especially because it is always changing as we learn more. The ISSA Nutritionist certification is the perfect way to build your nutrition knowledge base and to be able to offer clients an additional service.  

Featured Course


By becoming an ISSA Nutritionist, you'll learn the foundations of how food fuels the body, plus step by step methods for implementing a healthy eating plan into clients' lifestyles.


Liu, A. G., Ford, N. A., Hu, F. B., Zelman, K. M., Mozaffarian, D., & Kris-Etherton, P. M. (2017). A healthy approach to dietary fats: understanding the science and taking action to reduce consumer confusion. Nutrition Journal, 16(1), 53.

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