Low-fat, fat-free, skim, “good” fat and “bad” fat. A nutrient known to all, fat had a bad reputation during the 1990’s when the fat-free diet permeated American culture. Today, dietary fat is more accepted, but some are still apprehensive about it. How do you know which fats are good for you and which ones aren’t? The answer is more complex than you might think.
- Fat provides energy: One gram of fat contributes 9 calories, while one gram of carbohydrate contributes 4 calories.
- Is crucial for growth because it helps absorb fat-soluble vitamins A, E, D, and K from the foods we eat.
- It helps insulate the body against temperature extremes and protects internal organs.
Saturated fats come largely from animal sources like meat, dairy, and egg yolks; but there are also plant sources like coconut and palm oil.
Unsaturated fats are broken down into two categories: Monounsatured fats (MUFAs) and Polyunsaturated fats (PUFAs). MUFAs are found primarily in olive and canola oils, nuts, seeds, and avocados. PUFAs are found primarily in plant foods such as soybean, sunflower, corn and safflower oil. Polyunsaturated fats can be broken down even further into omega-3 and omega-6 fatty acids. These acids are called “essential fatty acids”, because they cannot be synthesized in the liver and have to be obtained through diet.
Trans fat is industrially created by hydrogenation (when unsaturated fatty acids have hydrogen atoms added to them). This process makes the fats more resistant to rotting and lengthens the shelf life of products with trans fat in them. You can find trans fat in processed foods like cakes, cookies, crackers, pies, and margarine. The Dietary Guidelines for Americans and American Health Association (AHA) recommend that trans fat be limited to about 2 grams per day for a 2000-calorie diet. Trans fat is linked to increased metabolic issues, plaque buildup in the blood vessels, and an increased risk of heart disease and stroke.
Weight-Maintenance and Recommendations
That brings us to this question: Does consuming high amounts of fat directly cause weight gain? If so, which types of fats? The answer is complicated. We know that consuming more calories than burned causes weight gain, and burning more calories than consumed causes weight loss. Where you get your calories from is another story.
The current dietary guidelines for Americans recommends that 20-35% of daily calories come from fat. However, health professionals are concerned that the typical Western diet is too high in saturated fat. In the United States, some of the top sources of saturated fat and trans fat come from cheese, bacon, pizza, French fries, and desserts. Diets high in saturated fat and trans fat (e.g. from fast food and highly processed foods) are linked to inflammation that can lead to coronary heart disease, insulin resistance, Type II diabetes, obesity, and cancer.
Additionally, there’s a concern that our American diet is too low in unsaturated fat. Unsaturated fats are said to benefit the body in a number of ways, including improving cholesterol levels and reducing inflammation. MUFAs and PUFAs, like those in fatty fish, can protect the body against diseases such as some cancers, rheumatoid arthritis, and dementia. Fatty fish is an excellent source of omega-3s, which keeps our hearts healthy. Eating fatty fish twice a week can help prevent heart disease and significantly reduce the risk of cardiac death.
In summary, studies have found no direct correlation between the percentage of calories from fat and negative health outcomes. However, we do know that the type of fat consumed is ultimately more important than the amount. Here are some tips to help you make good choices when incorporating fats in your diet.
- Pick foods that have unsaturated fats
- Limit foods high in saturated fat
- Avoid trans fat
- Fat: The Good, the Bad, and the Ugly (2009)
- Dietary Fat: The Good, the Bad, and the Ugly
- Fats and Cholesterol
- Overview of Health and Diet in America (2010)
- Omega-3 Versus Omega-6 Polyunsaturated Fatty Acids in the Prevention and Treatment of Inflammatory Skin Diseases
- Overview of Health and Diet in America