Low fat. Reduced fat. No fat. These labels are all over grocery stores creating fears that eating fat is bad for us. When did we become so afraid of fat? And is this fear justified?

We need fat to live. There is no getting around it. It’s our main source of energy, and gram per gram, provides more energy than protein or carbohydrates (9 calories per gram compared to 4 for protein and carbohydrate). It’s also needed for many functions in your body. For example, your nervous system needs fat (as part of the myelin sheath) so that nerve impulses can travel throughout your body.

History of Fat and Dietary Guidelines

Back in the 1950’s a nutritional war broke out between fat and sugar. On the line were billions of consumer dollars for the food industry that won. Sugar came out on top as fat was villainized for causing high cholesterol, heart disease and early death. Sugar was our saviour.

As a result, high fat foods were replaced with sugar and we were bombarded with commercials telling us fat is the dietary villain. Dietary guidelines followed suit saying to eat no more than 30% of daily calories from fat.

It worked. Fat in diets went down, while sugar intake increased. At the same time the number of people with obesity and diabetes climbed in many countries.

We’ve since learned how bad sugar is for us as well as other refined carbohydrates (white bread, white rice, simple cereals). But people were still told fat was something to be avoided.

In recent years, the lobbying tactics of the sugar industry have been exposed. Numerous studies in the 1960s and 1970s paid for by the sugar industry implicated fat as the culprit for heart disease and downplayed the bad effects of sugar. And even the research of famed Dr. Ancel Keys who is considered the founder of the link between fat and heart disease has come into question.

fat food

Good Fats, Bad Fats, Neutral Fats?

Not all fats are created equal. Some are considered healthy fats, such as mono- and poly-unsaturated fats, and some are considered not so healthy, such as saturated and trans fats. This led the foundation for the ground-breaking studies of the Mediterranean diet.

The Mediterranean diet focuses on fish, healthy oils/fats such as avocados, olive oil and nuts, as well as plant-based foods. Compared to the recommended low fat diet, the Mediterranean diet resulted in a reduction in heart attacks and early death in people with heart disease as well as preventing heart disease in those without it. In these studies, people ate more than 35% of calories from fat. Definitely not a low-fat diet.

But studying diets is hard. Mainly because we need food to eat. Unlike smoking, or physical activity, nutrition isn’t as black and white (not to say stopping smoking or starting more activity is easy, because they aren’t). With food, you can’t just tell someone to stop eating. If you design a study to reduce a food, usually it gets replaced with something else. The key is whether it is replaced with something that is healthier or not.

trans fat

Saturated Fat- Good or Bad?

While not all fats are equal, guidelines continue to caution us on saturated fats. These are fats predominantly from animal products. Saturated fat has been found to be associated with heart disease and early death in some but not all studies. Yet recent studies have questioned whether having these fats is really unhealthy. And it may depend on what you replace them with in your diet.

If you replace saturated fat with polyunsaturated fat (such as found in fish, nuts and seeds), this might be a healthier choice. But, if you replace them with carbohydrates, and particularly sugars and refined carbohydrates, this may actually increase your chances of heart disease and early death.

It also may depend on what food the fats come from. For example, saturated fats from cheese, yoghurt and fish were associated with lower risk for heart disease. In contrast, saturated fat from red meat and butter were associated with higher risk. And, while the type of saturated fat differs among these foods, these foods also contain a wide variety of other nutrients. These other nutrients may actually be more important to health than saturated fats.

There is, however, widespread agreement to limit or even avoid; trans fats. Trans fats are commonly found in commercial foods as they’re created during processing. Hard margarine and baked goods are examples. Trans fats comprise a small amount in our diet but pack an unhealthy punch by raising the bad cholesterol (LDL) and lowering the good cholesterol (HDL). As a result, if you eat a high amount of trans fats, it increases your chances for early death and disease.

Now with all that being said, when we eat, we eat whole foods. We don’t eat fat or protein or carbohydrate in isolation. These nutrients come in foods along with other nutrients, and we usually eat a variety of foods in combination. If you’re eating foods as close to their natural state as possible, for most people, there should be no need to count grams of fat.

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This post was originally published on May 15, 2019 and updated on January 19, 2022.