Three of the four macronutrients play critical roles in the healthy and proper functioning of the human body. Their roles in a keto lifestyle remain very important,however, the consumption amounts of each differ from standardized recommendations from the government and general consensus found currently in most health and nutritional documentation. Understanding the importance and role of each macronutrient provides insight into a responsible integration and adaptation to meet the goals and principles of keto or low carb living. In this article I will provide a detailed look into the macronutrient of Fat. This is Part 3 of a 5 part series on Understanding Macronutrients. Check out the rest of the series for a complete understanding of all the macros.


Dietary fats, which are broken down into fatty acids and glycerol, are required for tissue growth and hormone production. Fats provide energy, lubricate your tissues, carry fat-soluble vitamins into your body, protect and cushion your vital organs, and help to regulate body temperature. All dietary fats are composed of a mix of polyunsaturated, monounsaturated, and saturated fatty acids.

  • Polyunsaturated Fatty Acids: Fatty acids that have more than one unsaturated carbon bond in the molecule and are found mostly in plant-based foods and oils. Oils containing this type of fat are typically liquid at room temperature. These fatty acids are mainly in large quantities of sunflower, corn, and soybean oils; walnuts, pine nut; and sesame, sunflower, pumpkin, and flax seeds. Omega 3 fatty acids are a type of polyunsaturated fats found in seafood such as salmon and tuna, as well as, flax seeds and walnuts. These fatty acids may improve blood cholesterol levels, benefit insulin levels, control blood sugar and contribute vitamin E to the diet.
  • Monounsaturated Fatty Acids: Fatty acids that have one unsaturated carbon bond and are found in the greatest amounts within olive, canola, peanut, sunflower oils, avocados, peanut butter and most nuts. Oils containing them are liquid at room temperature. They are also part of most animal fats such as those from chicken, pork, beef and wild game. These fats are also generally considered healthy for the same reasons as polyunsaturated fats.
  • Saturated Fatty Acids: Fatty acids that have no double bonds between carbon molecules because they are saturated with hydrogen molecules. These fats are typically solid at room temperature. They are found mostly in coconut and palm kernel oils, butter, beef fats and in palm oil. They are also found in other animal fats, such as pork and chicken fats, and in other plant fats such as nuts. Saturated fats are often demonized as being unhealthy and increasing bad cholesterol resulting in a greater risk of heart disease. However, much of recent research and science suggest otherwise and the correlation between dietary saturated fat and heart disease is becoming less and less evident. In fact, saturated fats can elevate HDL cholesterol and increase LDL cholesterol size which are both important health benefits.
  • Trans Fatty Acids: This is a type of fat that occurs naturally in small amounts of some foods but most trans fats are made from oils through a food processing method called partial hydrogenation. They are found mostly in partially hydrogenated vegetable oils and foods containing these oils. Trans fats should be avoided as much as possible, especially, in foods that contain synthetic trans fats like partially hydrogenated oils found in margarine. (1,2,3,8)


The body can synthesize most of the fats it needs from the diet, however, there are two essential fatty acids the body must obtain directly from food. These two essential ones are linoleic acid (Omega-6) and linolenic (Omega-3) which are important in the normal functioning of all tissues in the body. The benefits of these essential fatty acids include: prevention of atherosclerosis, reduced incidence of heart disease and stroke, and relief from symptoms with ulcerative colitis, menstrual pain, and joint pain. Omega-3 fatty acid levels have been associated with a decreased breast cancer risk. It is recommended that omega-6 and omega-3 fatty acids be consumed in a ratio between 1:1 and 1:4 (omega-6 to omega-3) due to their internal competition for use by the body. Omega-6 fatty acids are found in leafy vegetables, seeds, nuts, grains, and vegetable oils. Omega-3 fatty acids are found in flaxseeds, walnuts, and in different oils such as flaxseed, canola, soybean, walnut, and wheat germ. Certain fish are good sources of omega-3 fatty acids although some research now suggests that fish or fish oil can contain unstable molecules that can release dangerous free radicals. Regardless, some fish in your diet is generally recommended. (4)


The U.S. Dietary Guidelines recommend that dietary fats should be 20-35% of total caloric intake for adults with slight variations based on age. These guidelines recommend reducing saturated fats and replacing with monounsaturated and polyunsaturated fats as much as possible. The World Health Organization (WHO) recommends that dietary fats should supply at least 15% of energy for adults. Women of reproductive age should consume at least 20% of energy from fat. The WHO advocates that sedentary people should not consume more than 30% from fat and active people may consume as much as 35%. Both the U.S. Guidelines and the WHO specifically recommend that less than 10% of caloric intake should come from saturated fat. (5,6)

Below is Table 1 that displays the daily nutritional goals by age and sex based on the Dietary Reference Intakes and Dietary Guidelines Recommendations. It shows the recommended amounts of fats to include the essential linoleic acid (Omega-6) and linolenic (Omega-3) along with the other macronutrients. (5)

Table 1 (5)


For anyone seriously considering the keto lifestyle having a basic understanding of the research regarding the health risks and benefits of fat intake is important. After all, taking on keto means you are going to eat a lot of fat – typically well over 60% of your caloric intake. Monounsaturated and polyunsaturated fats are generally considered healthy fats, however, trans and saturated fats are considered unhealthy by many in the medical and health community. The health risks of trans fat is pretty much indisputable, however, recent research and science suggest that saturated fats are more healthy than previously understood. An emerging better understood and interesting paradox that occurs on keto is that the more saturated fat you eat the more saturated fat levels in your blood go down. This occurs because keto-adapted people dramatically increase the rate that their bodies burn saturated fat. More and more science and research is also suggesting that there is no link between saturated fat and the increased risk of heart disease. (7)

When you cut back on carbohydrates to the point that fats get burned first, the saturated fats go to the front of the line, and if you burn them up for energy before they can accumulate, how are they going to harm you?

Volek, PhD, RD; Phinney, MD, PhD (7)

A simple way to think about dietary fat consumption on keto is the following. Your body gets energy from two primary sources, carbohydrates and fats. Alcohol is not a good energy source for obvious reasons and protein is essential but it isn’t a preferred source of direct energy.  So you are left with two choices, carbs or fat, while you keep protein moderate which is essential for bodily functions and overall health. If you severely restrict carbs while on keto (less than 30 grams), then your only energy source left is fat. If you understand the recent science regarding fat, make responsible choices on which fats you eat, stay within your recommended caloric intake, and keep protein moderate (goal of .8 – 1 gram per pound of lean body mass) then fat is an essential and necessary part of your ability to maintain energy and survive. It becomes your body’s primary fuel source and it should be treated (and eaten) as such. Instead of filling your body’s energy tank with sugar fuel, you are filling it with a higher octane fat fuel.


My fat consumption ranges from 60-70% of my daily caloric intake which allows me to get all the protein I need, as well as, fiber from the “good” carbohydrates. An interesting and often overlooked part of this lifestyle is that foods that are high in protein are often just as high or higher in fats which means you get the best of both macro worlds in some of the same foods. These foods are typically meats and others such as eggs, nuts, and dairy (butter, cheese, cream). Shying away from protein often means missing opportunities to eat healthy fats which is counterproductive to the keto lifestyle – not to mention difficult. I eat an assortment of meat to include chicken, beef, pork and fish throughout the week to obtain both fat and protein. I try to get my allowance of Omega-3 and Omega-6 essential fatty acids primarily through leafy greens and nuts. MCT (medium chain triglycerides) oil is something I consume daily. Fats, and more so protein, have extremely satiating effects which is why the keto lifestyle is such a powerful weight loss and management tool. I always strive to reach my caloric intake goals, especially since I am trying to maintain or gain lean muscle mass as part of an intense exercise regime, but if I fall short it is mainly in the fat category – protein and the “good” carbs (fiber) are my non-negotiables. Fat acts like a “lever” to fill out the rest of your calories once you have met your protein goal. The research I have done and feedback from others I have had the privilege to meet and help suggest that this approach works regardless of your exercise level or current health conditions. Don’t be afraid to eat fat.



  1. Briffa, Escape the Diet Trap, 2012.
  2. Nutrition and healthy eating, Mayo Clinic, 2016. http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fat/art-20045550
  3. American Heart Association, https://healthyforgood.heart.org/
  4. Final Determination Regarding Partially Hydrogenated Oils, Federal Register, FDA, 2015. https://www.federalregister.gov/articles/2015/06/17/2015-14883/final-determination-regarding-partially-hydrogenated-oils
  5. Dietary Guidelines For Americans 2015 -2020, Eight Edition. https://health.gov/dietaryguidelines/2015/resources/2015-2020_Dietary_Guidelines.pdf
  6. Essential Fatty Acids, Physician’s Committee for Responsible Medicine, http://www.pcrm.org/health/health-topics/essential-fatty-acids
  7. Volek, Phinney, The Art and Science of Low Carbohydrate Living, 2011.
  8. Wilson, Lowery, The Ketogenic Bible, 2017.

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