Why Dietary Fat Is Good in Moderation

Fat has earned a bad reputation and is sometimes blamed for the “battle of the bulge.” It’s true that dietary fat is a more concentrated source of calories than protein or carbohydrates. A gram of fat has almost twice the calories of a gram of protein or carbohydrates. But not all fat is bad. In fact, you need a certain amount of fat in your diet to be healthy. Here are the reasons why some fat is good for you.

Dietary Fat: Why Fat is Good in Moderation

One of the main reasons you need fat in your diet is because of two essential fatty acids called alpha-linolenic acid and linoleic acid. Your body needs them but can’t make them. These two essential fatty acids are used to synthesize hormone-like molecules called eicosanoids that control a variety of functions in the body, including inflammation.

Essential fatty acids are also important for synthesizing brain chemicals that affect mood. Very low-fat diets are associated with a greater risk of depression and other mood disorders. Some studies have even linked very low-fat diets with a higher risk of suicide. Keep in mind this probably only applies to diets that are extremely low in fat. Some research shows that diets containing moderately low amounts of fat have the opposite effect. They improve mood and are less likely to make you feel grumpy and depressed than a low-carbohydrate one. Still, you need some fat in your diet to synthesize brain chemicals involved in mood and behavior.

Dietary Fat: You Need Fats to Absorb Some Vitamins

Certain vitamins are fat-soluble, meaning they must be dissolved in fat to be absorbed by the intestines and enter the body. Dietary fats provide a way for these vitamins to be absorbed rather than excreted in the feces without being used. Fat-soluble vitamins include vitamins A, D, E and K. A very low-fat diet increases the risk of being deficient in one of these vitamins.

Dietary Fat: Fats May Even Help with Weight Loss

Despite the fact that fat is more calorically dense, it may still help with weight control. Adding some fat to every meal slows down how fast the stomach empties food. This helps to reduce hunger. You’ve probably already noticed how full you feel after you’ve eaten something rich.

Dietary Fat: Other Important Functions of Fat

You need fat for soft, supple skin and for healthy nerves. Nerve cells are surrounded by sheaths made of a fatty material called myelin that helps to insulate them. Fat is also an important part of the membrane that surrounds every cell in the body. If you eat a very low-fat diet, you could suffer from dry skin, hair loss and lower resistance to infection.

Dietary Fat: Fat is Good When You Choose Healthy Ones

The key to getting the benefits of fat without the downsides is to choose healthy fats. Avoid saturated fats in fatty meat and dairy foods, and choose polyunsaturated and monounsaturated ones found in nuts, flaxseed, soybeans, olive oil, and avocado. Fatty fish such as wild salmon, tuna and sardines are good sources of healthy polyunsaturated fats called omega-3 fatty acids. These fats help to lower inflammation and reduce the risk of heart disease. Fats really can be heart-healthy.

The Bottom Line?

Fat is good in moderation, and it’s necessary for health. Keep your total fat intake at between 25-30% of your total calories, and choose foods rich in monounsaturated and polyunsaturated fats. Avoid processed foods that contain saturated fats, and the worst kind of fat, trans-fat. Read labels carefully when shopping.

References:

Nutrition Reviews. Volume 58, Issue 4, pages 98–108, April 2000.