Healthy Fats vs. Unhealthy Fats: What You Need to Know

Healthy Fats vs. Unhealthy Fats: What You Need to Know

Research about fat is confusing, and the internet is rife with conflicting recommendations.

Much of the confusion happens when people make generalizations about fat in the diet. Many diet books, media outlets and blogs talk about fats as though they were all the same.

In reality, dozens of fats are common in the diet, and each one has a different role in the body and effects on your health. Even within groups of fats like saturated, unsaturated and polyunsaturated, specific fats still have different roles.

This article will explain the differences between some of the main dietary fats and their health effects, both good and bad.

The key is to understand that each type of fat has its own unique effects on the body. Once you start thinking about fats more specifically, you’ll be better equipped to make healthy dietary choices.

How Fat Became a Dirty Word
Decades ago, common sense was to eat fatty foods because it was the most efficient way to get energy. Fat contains more calories by weight than any other nutrient.

Over time, scientists began to understand that some fats are healthier than others. In the 1930s, Russian scientists found that feeding animals very high-cholesterol diets caused atherosclerosis (1).

This is a condition where plaque builds up in the arteries, narrowing them and increasing the risk of heart disease. Atherosclerosis is the most prominent cause of heart disease and stroke (1).

In the 1940s and ‘50s, heart disease in multiple countries decreased. Many attributed this phenomenon to wartime rationing in World War II. This fueled the belief that fat and cholesterol, which were high in the restricted foods, contributed to heart disease.

The Seven Countries Study, a large international study directed by American physiologist Ancel Keys and other international scientists, revealed several important risk factors for heart disease.

These included smoking, high blood pressure, weight gain, yo-yo dieting and blood cholesterol (2).

The Seven Countries Study contributed to the hypothesis that saturated fat increased blood cholesterol, predicting atherosclerosis and heart disease (3Trusted Source).

However, even decades ago Ancel Keys recognized not all fat is harmful. He was skeptical of the importance of dietary cholesterol and showed unsaturated fats reduce the risk of heart disease (4Trusted Source).

Unfortunately, his and other researchers’ science has been much misquoted by policymakers, nutritionists and journalists.

Black and white, extreme conclusions, such as “all saturated fat is bad” or “everyone should eat a low-fat diet,” are not helpful nor correct. This article will demystify the confusing literature on fat by looking at a combination of old and new research.

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