By Aaron Boike, B.S. Kinesiology, ACE Certified Personal Trainer
“Eat real food, not too much, mostly plants” – Michael Pollan
Fats have gotten a bad wrap over the last century. First demonized for the flawed “eat fat, get fat” logic promoted by faulty research done in the mid-20th century; our understanding of the role of fat in the diet has changed dramatically in the last couple of decades. Even though we are armed with more research than ever, it is hard to make sense of the research and how it impacts your diet. We’re going to break down the different types of fat, what the research tells us about them, and if they are something you should be including in your diet on a regular basis or keeping to a minimum.
What Is Fat?
Fat is a macronutrient found is just about all natural foods. It is nine calories per gram, about twice what a single gram of carbohydrate or protein contain. Many fats are considered “essential,” meaning that they must be obtained through the diet and cannot be made by the human body. Fats are essential for building healthy cell membranes, skin, hair, controlling inflammation, brain development, and blood clotting.
Unsaturated Fats
Unsaturated fats are fats that contain fewer hydrogen atoms bonded to their carbon chains. This makes them liquid at room temperature. These types of fats come from nuts, seeds, vegetables, vegetable and seed oils, and fish. They classified as either monounsaturated (missing one hydrogen bond), or polyunsaturated (missing multiple hydrogen bonds). While it was previously thought that all unsaturated fats were desirable in the diet and a healthy alternative to saturated fats, research has shown us that the balance between Omega-6 and Omega-3 fats is vitally important to our health. In the past, we had diets high in omega-3, which is found in many natural foods such as nuts, seeds, plants, and animal protein. With the advent of processed foods and subsequent demonization of saturated fats in the 20th century, cheap refined vegetable oils and shortenings became the choice for most food producers. These oils are high in omega-6 fatty acid and low in omega-3, tipping off the balance of omega-6 and omega-3 fats in our diet. This imbalance has been shown to correlate with increased risk of heart disease, increased inflammation, and poor immune function. When it comes to unsaturated fats, focus on the ones that come from natural whole food sources (nuts, seeds, avocados, fish), while avoiding the ones from refined oils (corn oil, safflower oil, Crisco, soybean oil, peanut oil etc). When using oil; however, your best bets are olive oil and avocado oil, as they have a higher ratio of healthy unsaturated fats.
Saturated Fats
Saturated fats are fats that contain a complete set of hydrogen-carbon bonds. They are solid at room temperature, and are mainly found in animal products, coconut oil, and many processed foods. The jury is still out on saturated fats, with some research showing increased risk of cardiovascular disease with higher consumption due to an increase in overall cholesterol, and others finding little to no change in risk, despite the change in overall cholesterol levels. One important factor that is often overlooked in research conclusions is the balance between HDL / “Good Cholesterol”, and LDL / “Bad Cholesterol.” In addition, research now shows that there are two types of LDL, larger “fluffy” LDL particles and small dense particles, with the latter being promoted by eating saturated fats in combination with a diet high in refined carbohydrates and sugar. Our understanding of how these different types of cholesterol interact may hold the key to understanding if saturated fats can be a healthy part of our diet. My rule of thumb is stick to natural whole food sources of saturated fat, rather than consuming fats found in processed goods.
Trans Fats
While we still have much to understand when it comes to unsaturated and saturated fats, it is without question that trans fats are to be avoided in the diet. Trans fats occur when a hydrogen bond is added to an otherwise unsaturated fat, making it stable and solid and room temperature. This feature of trans fats makes them a popular addition to processed foods, as they extend shelf life and prevent foods from becoming rancid. Trans fats can be found in margarine, vegetable shortening, processed cookies, crackers, baked goods, and fast food french fries. These fats have been shown to promote inflammation, reduce insulin resistance (leading to Type II Diabetes), raise LDL cholesterol, and dramatically increase the risk of heart disease when consumed on a regular basis.
In conclusion, fat is an essential and healthful part of our diet and plays vital functions in the body and should not be avoided altogether. Considering what we know based on current research, it is likely best to stick to mostly whole food plant based sources of fat, while eating a moderate amount of saturated fats, and eliminating trans fats from the diet.
Sources:
Hyman, Mark, 2017, “Eat Fat, Get Thin – Fat Bible” https://www.eatfatgetthin.com/dist/pdf/Fat_Bible_ebook_final.pdf, Accessed 6/20/17.
Harvard Health Publications, 2017, “The Truth about Fats, the Good, the Bad and the in-Between”, http://www.health.harvard.edu/staying-healthy/the-truth-about-fats-bad-and-good, Accessed 6/20/17