Every single gram of fat has 9 calories, which is more than double the energy of protein or carbohydrates. Fats (or fatty acids, also known as lipids) play a number of essential roles in our ability to thrive and survive. Dietary fats facilitate the transportation and absorption of the fat-soluble vitamins A, D, E and K as well as a number of other nutrients. You may be surprised to learn that many medications prescribed as to be taken with food is done so for this very reason, and not because they may otherwise upset your stomach; it’s so that you’re able to absorb as much of the medication as possible as facilitated by the fat that’s eaten with your food. Dietary fats also slow down the digestion of foods, which helps keep you feeling satiated for a longer time, and the Omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) support cardiovascular health, joint health and digestion. Body fat insulates your body to help maintain your temperature, protects your vital organs and assists with brain functions. Fat is a part of every single cell, organ and tissue within your body.

We love fat because it improves the texture of the foods we eat and makes things taste better, which is why it’s so popular in fast food and at restaurants! Fats are invisible when in a cooked dish, often melted or consumed in a liquid form so it’s really easy to underestimate how much of it you are eating. Not all fats are created equal and the type of fats that we are consuming is important. The most readily available and used in restaurants and often the cheapest found in supermarkets are the least healthy for you.

Saturated and Unsaturated Fats

Fats are classified by their chemical structure as being either saturated fats, or unsaturated fats of which there are two: monounsaturated and polyunsaturated. Saturated fats have no double bonds in their chemical structure and as such they are saturated with hydrogen atoms. Because of this chemical structure, saturated fats are hard at room temperature. Monounsaturated fats have one double bond in their structure and because of this chemical structure they are typically liquid at room temperature, but will harden if temperatures drop some. Polyunsaturated fats contain two or more double bonds in their chemical structure and as such these are always liquid at room temperature. Unsaturated fats are not fully saturated with hydrogen atoms.

Saturated fat is mainly found in animal foods, however some plant foods such as coconut, coconut oil and palm oil are also high in saturated fats. It’s recommended that we eat less than 10% of our fats, or no more than 7% of our caloric intake from saturated fat sources. All foods containing fat will have a combination of each specific type. Foods like beef, cheese or ice cream have high amounts of saturated fats, while chicken and nuts have small amounts. Research surrounding fats is currently muddy, with most evidence suggesting that cutting back on saturated fats by replacing it with the unsaturated fats (often referred to as the good fats), is good for our overall health.

Unsaturated fats predominately found in plants, nuts and seeds are considered good fats because they have shown to improve blood cholesterol levels, to ease inflammation, and stabilize heart rhythms while playing a number of other important roles in our bodies. Recent studies show an association between eating higher levels of unsaturated fats and a lower risk of Alzheimer’s and Dementia[1], as well as increased cognitive function. Monosaturated fats found in high concentrations in foods such as olives, nuts, canola oils, avocados, and seeds have shown to reduce the amount of LDL (bad cholesterol) in our blood. Polyunsaturated fats found in vegetable oils, fatty fish, canola oil (which is also high in monounsaturated fat), flax seeds and walnuts reduce the LDL (bad cholesterol) while also reducing HDL (good cholesterol) slightly. In trials in which polyunsaturated and monounsaturated fats were eaten in place of carbohydrates, these good fats decreased levels of harmful LDL and increased protective HDL.[2] A randomized trial known as the Optimal Macronutrient Intake Trial for Heart Health (OmniHeart) showed that replacing a carbohydrate-rich diet with one rich in unsaturated fat, predominantly monounsaturated fats, lowers blood pressure, improves lipid levels, and reduces the estimated cardiovascular risk.[3]

Essential Fatty Acids

The Omega-3 and Omega-6 fatty acids are considered the essential fatty acids because the human body cannot make them. These are an important type of unsaturated fat that must come from the foods we eat. While consumption of both fatty acids is necessary, the average western diet has people eating far more Omega-6 than needed, while eating a deficient amount of Omega-3. Research suggests that the ratio between the two matters most when it comes to health benefits, as such we aim to increase the intake of whole foods that are high in Omega-3 and low in Omega-6. These include foods like fatty fish or grass fed beef & butter (grain fed has higher amounts of Omega-6), vegetable oils, nuts (especially walnuts), flax seeds, flaxseed oil, and leafy vegetables.

Omega-3 fats are an integral part of every cell membrane, affecting the function on the cell receptors within the human body. They play an integral part in hormone creation for blood clotting, contraction and relaxation of artery walls and even inflammation. Omega-3 fat has been shown to help prevent heart disease and stroke, and may play protective roles in cancer and other conditions, while helping to control lupus, eczema, and other rheumatologic illnesses.

There are three main Omega-3 fats: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) which mainly come from fish, and then there is ALA (alpha-linolenic acid) which is the most common in Western diets, found in vegetable oils, nuts (especially walnuts), flax seeds and flax oil, leafy vegetables, and some animals – mainly those that are grass fed. ALA is mainly used by the human body for energy. Conversation of ALA into EPA or DHA is limited[4]. When a person’s diet is not rich in Omega-3 fats, we recommend increasing Omega-3 through supplementation of tablets in the amount of 2-3 grams of combined EPA and DHA per day in order to close the gap between the average ratio between Omega-3 and Omega-6.

Cholesterol

Cholesterol, while often made to sound like a villain linked to heart attack and stroke, is beneficial to many important body functions. In fact, we need cholesterol to make cell membranes and key hormones like testosterone and estrogen, which is one of the reasons adequate fat intake is important, particularly for women. Cholesterol also helps produce the bile acid that’s required to digest and absorb dietary fats and it plays a role in producing vitamin D. In fact, cholesterol is so important to us, our own liver and intestines will make some of it from scratch. Cholesterol becomes the enemy when there is abundance or lacking balance between the types of it within the bloodstream.

There are two main types of cholesterol within the body, the first being high-density lipoproteins (HDL) that is often referred to as the ‘good’ cholesterol. This is because it may protect the body against narrowing blood vessels. The second main type of cholesterol is low-density lipoproteins (LDL), known as the bad cholesterol. Too much LDL will create the harmful plaques that grow inside arteries and are responsible for angina, heart attacks and many types of strokes. While genetics may sometimes play a part in high LDL levels, diet is often the culprit. Eating foods rich in saturated fats and easily digested carbohydrates will boost the amount of LDLs in the bloodstream. There is a third type of cholesterol called VLDL (very-low-density lipoproteins), which is another variation of bad cholesterol produced in the liver.

Trans Fats

Trans fats (or trans fatty acids) are most often synthetically made, but may also found naturally in small amounts in beef and dairy fats. A process known as hydrogenation is heating unsaturated liquid vegetable oils in the presence of hydrogen gas along with a catalyst to saturate the oils with hydrogen. By partially hydrogenating vegetable oils it converts the liquids into a solid such as margarine or shortening, and it makes them more stable and less likely to become rancid. Trans fats are mainstay in the fast food industry and in restaurants for these reasons and also because they do not break down with repeated heating which makes them ideal for frying fast foods. In addition to all of this trans fats are inexpensive and easy to produce. These types of fats are found in all kinds of restaurant or store-bought and processed foods such as fried foods, donuts, pizza dough, breads and other baked food, cookies, crackers, chips, etc.

Trans fats do not promote good health, but instead are known to be the worst type of fat for the heart, blood vessels and rest of the body. They are known the raise LDL and lower HDL levels, to create inflammation that is implicated in heart disease, stroke and other chronic conditions while contributing to insulin resistance and type 2 diabetes.

There is absolutely no safe amount of trans fat intake and as such some western societies are working to ban them all together. We should all be minimizing the amount of trans fats in our diets, by preferably not having any of it at all.

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[1] https://www.health.harvard.edu/staying-healthy/know-the-facts-about-fats
[2] Mensink, R.P., et al., Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials. Am J Clin Nutr, 2003. 77(5): p. 1146-55.
[3] Appel, L.J., et al., Effects of protein, monounsaturated fat, and carbohydrate intake on blood pressure and serum lipids: results of the OmniHeart randomized trial. JAMA, 2005. 294(19): p. 2455-64.
[4] https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-and-cholesterol/types-of-fat/omega-3-fats/