Fats

Fats serve many critical functions in the body. Fats provide a readily available source of stored energy during times of caloric deprivation, help thermally insulate the body, protect vital organs and bones, help the body absorb vitamins, regulate nerve transmission, support cell function, and produce important hormones [1, 2, 3, 4, 5]. Fat is the most energy-dense of the three macronutrients (providing 9 calories per gram), which means that it can contribute to obesity, cardiovascular disease, and overall poor health if consumed in excess [3, 4, 6]. While its high caloric density can easily and quickly contribute to weight gain, certain types of fat are heart-healthy and excellent sources of essential nutrients. There are four categories of fats known as trans fats, saturated fats, monounsaturated fats, and polyunsaturated fats.

Trans Fats

Trans fats are the product of the hydrogenation process, which is a man-made effort to make an unsaturated fat solid at room temperature with the intention to prolong shelf life [1, 4]. Both partial and full hydrogenation cause changes to cell membrane fluidity and negatively affect cell function in the body [1, 4]. These synthetic trans fats significantly elevate low-density lipoprotein (LDL) cholesterol, which is the bad cholesterol [4, 5]. Trans fats are also linked to an increased risk of heart disease, diabetes, and cancer [1, 4, 5].

Saturated Fats

Saturated fats are normally very stable and solid at room temperature. Saturated fats are naturally occurring fats in animal sources (e.g., red meat) and full-fat dairy products [4, 5]. Because saturated fats increase LDL cholesterol and are linked with cardiovascular disease, the American Heart Association (AHA) and 2015-2020 Dietary Guidelines advise consumers to either avoid or significantly reduce the consumption of saturated fats [4]. Saturated fats should not be viewed as good for you, but a balanced diet can include saturated fats [3]. The recommendation is to consume fewer than 10 percent of total calories from saturated fats [4, 6]. Replacing saturated fats with polyunsaturated fats (like omega-3 and omega-6 fatty acids) is beneficial for overall health and cardiovascular disease risk mitigation [3].

Monounsaturated Fats

Monounsaturated fats are one of two types of unsaturated fats. Unsaturated fats are normally unstable and liquid at room temperature [3]. Unsaturated fats are found in plant sources and have a shorter shelf life than trans fats and saturated fats [3]. Monounsaturated fats are heart-healthy; they lower blood cholesterol levels, and therefore reduce the risk of cardiovascular disease [3, 4, 5]. Most plant oils (e.g., olive, sesame seed, and avocado) are excellent sources of monounsaturated fat. According to the National Institutes of Health, in the context of a diet moderately high in carbohydrates, consuming monounsaturated fats as compared to saturated fats leads to greater fat burning, reduced body fat (particularly abdominal fat), and improved insulin sensitivity, and increased satiety. The Academy of Nutrition and Dietetics recommends that 15-20 percent of total caloric intake comes from monounsaturated fats [4].

Polyunsaturated Fats

Polyunsaturated fats are the healthiest of fats and are especially important for optimal health. In fact, substituting polyunsaturated fats for saturated fats and refined carbohydrates contributes to a significant risk reduction of cardiovascular disease [1, 3, 4, 5, 6]. The two main types of polyunsaturated fats are omega-3 and omega-6 fatty acids, which are essential fatty acids that must be obtained from diet (or supplementation), because the body cannot produce them [1, 3, 4, 6]. Both omega-3 and omega-6 fatty acids are important for brain function and cell growth [1, 3, 4].

Omega-3 (Alpha-Linolenic Acid). A diet high in omega-3 fatty acids has been shown to help protect the heart from cardiovascular disease [5]. Overall, omega-3 fatty acids reduce blood clotting, dilate blood vessels, and reduce inflammation [1, 3, 4, 6]. They play a crucial role in growing a fetus in the late stages of pregnancy [1, 3, 4]. They reduce cholesterol and triglyceride levels [1, 3, 4, 5]. They are important for eye and brain development [1, 3, 4]. They also contribute to preserve brain function and reduce the risk of mental illness and attention deficit hyperactivity disorder (ADHD) [1, 3, 4]. Most Americans tend not to consume enough omega-3 fatty acids, although this recommendation can be met through the consumption of approximately 8 ounces of a fatty fish per week [4]. Examples of fatty fish include salmon, mackerel, herring, lake trout, sardines, and albacore tuna. Though natural food sources are best, people who do not meet this recommendation or do not like fish may benefit from omega-3 supplementation or from fortified food (e.g., eggs, margarine, or milk) [4].

Athletes who engage in strenuous exercise experience an increase in many of the compounds associated with inflammation that are like those induced by infection [6]. Omega-3 fatty acids provide benefits for athletes as well as a variety of performance-enhancing effects, such as increasing muscle growth, improving strength and physical performance, reducing exercise-induced muscle damage and delayed-onset muscle soreness (DOMS), combating negative immune effects of intensive training, strengthening bones, improving heart and lung function, and enhancing cognitive function [6]. Approximately 1-2 grams per day of omega-3 fatty acids, with an eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) ratio of 2:1, can improve cardiovascular function and exercise performance [6].

Omega-6 (Linoleic Acid). Along with omega-3 fatty acids, omega-6 fatty acids play a crucial role in brain development and function [7]. Omega-6 fatty acids help stimulate skin and hair growth, maintain bone health, regulate metabolism, and maintain the reproductive system [7]. They help regulate blood sugar levels by improving the body’s sensitivity to insulin [8]. They also lower harmful low-density lipoprotein (LDL) cholesterol and raise protective high-density lipoprotein (HDL) cholesterol [8]. Examples of omega-6 fats include green leafy vegetables, safflower oil, sunflower oil, corn oil, soybean oil, sunflower seeds, walnuts, and pumpkin seeds [4, 8]. The AHA and Institute of Medicine recommend obtaining 5-10% of total daily calories from omega-6 fatty acids [8].

Fats and Athletic Performance

There is no evidence for performance benefit from a very low-fat diet (<15 percent of total calories) or from a high-fat diet [1, 3]. Omega-3 fatty acids provide a variety of performance-enhancing effects for athletes, such as increasing muscle growth, improving strength and physical performance, reducing exercise-induced muscle damage and delayed-onset muscle soreness (DOMS), combating negative immune effects of intensive training, strengthening bones, improving heart and lung function, and enhancing cognitive function [6].

Fat Recommendation

• Per the Acceptable Macronutrient Distribution Range (AMDR), which was developed by the Institute of Medicine, fats should account for 20-35 percent of total daily calories [1, 3, 4].

• Consume fewer than 10 percent of total calories from saturated fat [4].

• The Academy of Nutrition and Dietetics recommends that 15-20 percent of caloric intake come from monounsaturated fatty acids [4].

• The Academy of Nutrition and Dietetics recommends that intake from polyunsaturated fatty acids comprise 3-10 percent of total caloric intake [4].

• Approximately 1-2 grams per day of Omega-3 fatty acids, with an eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) ratio of 2:1, can improve cardiovascular function and exercise performance [6].

• The AHA and Institute of Medicine recommend obtaining 5-10 percent of total daily calories from omega-6 fatty acids [8].

Sources

[1] Bryant, C. X., & Green, D. J. (2017). Ace Essentials of Exercise Science for Fitness Professionals. American Council on Exercise.

[2] Efferding, S., & McCune, D. (2021). The vertical diet. Victory Belt Publishing.

[3] Muth, N. D., & Tanaka, M. S. (2013). Ace Fitness Nutrition Manual. American Council on Exercise.

[4] Muth, N. D., & Zive, M. M. (2020). Sports nutrition for health professionals (2nd ed.). F.A. Davis.

[5] Zinczenko, D., & Spiker, T. (2010). The new ABS diet: The six-week plan to flatten your belly and firm up your body for life. Rodale Press.

[6] Bertucci D R Ferraresi C 2016 Strength Training: Methods, Health Benefits and DopingBertucci, D. R., & Ferraresi, C. (2016). Strength Training: Methods, Health Benefits and Doping. Nova Science Publishers. https://eds-s-ebscohost-com.ezproxy.umgc.edu/eds/ebookviewer/ebook/bmxlYmtfXzExMzQ0NTZfX0FO0?sid=b5e6955f-8aa1-4fff-906c-5bba28f3d5d2@redis&vid=1&format=EB&rid=1

[7] Omega-6 fatty acids. Mount Sinai Health System. (n.d.). https://www.mountsinai.org/health-library/supplement/omega-6-fatty-acids

[8] No need to avoid healthy omega-6 fats. Harvard Health. (2019, August 20). https://www.health.harvard.edu/newsletter_article/no-need-to-avoid-healthy-omega-6-fats