Dietary fat often stands in the shadow of carbohydrates and protein when it comes to sports nutrition recommendations. Despite this, fat still plays an important role in an athlete’s diet.
Introduction
If you’re a regular reader of the blog, you’ll know that carbohydrates are the optimal fuel for fuelling exercise performance. In addition, you’ll also likely appreciate the importance of eating enough protein to help facilitate recovery. What you’re likely less familiar with—because we haven’t really written about it—is the role of fat in an athlete’s diet. While not as crucial as carbohydrates or protein, fat is still an important nutrient for athletes that impacts a number of bodily processes that can affect health and performance.
What is Dietary Fat?
Dietary fat is one of the three main macronutrients (the others being carbohydrates and protein) and is a major energy source. Fat is the main fuel burned when we engage in everyday activities like breathing, sitting, and sleeping, as well as low-intensity activities like walking and light jogging. Because fat is so crucial for fuelling our everyday activities, our bodies are designed to store a lot of body fat in reserve so that we can call on these stores when times get tough (e.g., during a shortage of food). Our seamless ability to store fat was particularly beneficial throughout history, when we would often be without food for long periods of time. However, as you can imagine, this trait doesn’t serve us too well in the modern industrialised Western world.
Common food sources of fats.
Types of Fats
The most common dietary fats (or fatty acids) are saturated, monounsaturated, and polyunsaturated fats. Saturated fats are commonly found in animal-source foods (e.g., dairy foods, fatty meats) as well as certain plant-source foods (e.g., coconut oil, palm oil). Monounsaturated fats are most often found in plant-source foods like olive oil, avocado, nuts, and seeds. Likewise, polyunsaturated fats are commonly found in plant-source foods like vegetable oils, nuts, and seeds, as well as oily fish like salmon, mackerel, and sardines.
When it comes to health, it is recommended to limit saturated fats in favour of mono- and polyunsaturated fats, because the latter reduce causal risk factors of heart disease (e.g., low-density lipoprotein cholesterol, apolipoprotein B) and are thus associated with a reduced risk of heart disease (1,2,3).
Figure 1. Chemical structures of different types of fatty acids. Saturated fatty acids have no double bonds between carbon atoms in the hydrocarbon chain, making them fully saturated with hydrogen atoms. Monounsaturated fatty acids contain one double bond between carbon atoms in the hydrocarbon chain, whereas polyunsaturated fatty acids contain more than one double bond between carbon atoms in the hydrocarbon chain. Image source: iHealth Unified Care.
The Role of Fat in an Athlete’s Diet
Because carbohydrates are the preferred fuel for moderate- to high-intensity exercise, eating enough fat is not a major priority from a fuelling for performance point of view. Where fat may play an important role in athletes’ diets is in relation to:
Meeting essential nutrient requirements
Fat-soluble nutrient absorption
Immune function and hormone production
Meeting Essential Nutrient Requirements
A very low-fat diet can place an athlete at risk of being deficient in certain essential nutrients. While our body can make a range of fatty acids, we cannot make the omega-6 fatty acid linoleic acid (LA) or the omega-3 fatty acid alpha-linolenic acid (ALA) (both polyunsaturated fats). Therefore, we must get these nutrients from our diet, so if athletes are eating a very low-fat diet, they are at risk of not getting enough of these important nutrients. ALA can be converted to the long-chain omega-3 fatty acids DHA and EPA; however, conversion rates vary between individuals so it is recommended to eat a direct source of DHA and EPA (from oily fish, or through fish oil or algae oil supplements).
Fat-Soluble Nutrient Absorption
Vitamins A, D, E, and K are known as fat-soluble vitamins. This means that they dissolve in fats and oils, and are stored in fat within the body. If we eat these vitamins without a source of fat, they will be poorly absorbed in the digestive system. This is also the case if we take these nutrients in supplemental form without a source of fat. So as an athlete, it's important to eat a good source of fat with meals and when taking supplements so that you absorb these nutrients.
Immune Function and Hormone Production
Low-fat diets have been reported to compromise immune function, as fats are known to play a role in regulating immune function through several factors (4). Dietary fats also serve as precursors for steroid hormones (e.g., testosterone, oestrogen), so very low-fat diets could compromise their production which could result in poorer health and exercise performance.
Summary
While fats are often neglected in sports nutrition, they do play a role in maintaining the good health and performance of athletes. Therefore, it is recommended that athletes do not restrict dietary fats to less than 20% of their daily energy (calorie) intake (5). In practice, this can be achieved by ensuring that each main meal throughout the day includes a good source of fat.
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Thanks for reading!
Patrick Elliott, BSc, MPH
Health and Nutrition Science Communication Officer at Training121
Instagram: @just.health.info
Twitter/X: @PatrickElliott0
References
(1) Christensen JJ, Arnesen EK, Rundblad A, Telle-Hansen VH, Narverud I, Blomhoff R, Bogsrud MP, Retterstøl K, Ulven SM, Holven KB. Dietary fat quality, plasma atherogenic lipoproteins, and atherosclerotic cardiovascular disease: An overview of the rationale for dietary recommendations for fat intake. Atherosclerosis. 2024;389:117433. Available at: https://www.sciencedirect.com/science/article/pii/S0021915023053546
(2) Mensink RP. Effects of Saturated Fatty Acids on Serum Lipids and Lipoproteins: a Systematic Review and Regression Analysis. World Health Organization. 2016. Available at: https://iris.who.int/bitstream/handle/10665/246104/9789241565349-eng.pdf
(3) Li Y, Hruby A, Bernstein AM, Ley SH, Wang DD, Chiuve SE, Sampson L, Rexrode KM, Rimm EB, Willett WC, Hu FB. Saturated Fats Compared With Unsaturated Fats and Sources of Carbohydrates in Relation to Risk of Coronary Heart Disease: A Prospective Cohort Study. J Am Coll Cardiol. 2015;66(14):1538–48. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4593072/
(4) Venkatraman JT, Leddy J, Pendergast D. Dietary fats and immune status in athletes: clinical implications. Med Sci Sports Exerc. 2000;32(7 Suppl):S389–95. Available from: https://journals.lww.com/acsm-msse/fulltext/2000/07001/dietary_fats_and_immune_status_in_athletes_.3.aspx
(5) Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Acad Nutr Diet. 2016;116(3):501–28. Available at: https://www.sciencedirect.com/science/article/pii/S221226721501802X
Technical Terms
Saturated fats: In chemical terms, these are fatty acids that have no double bonds between carbon atoms in the hydrocarbon chain, meaning all of their carbon atoms in this chain are fully saturated with hydrogen atoms. Saturated fats have many subtypes that vary in carbon chain length. It is recommended to limit saturated fats in the diet because they can increase low density lipoprotein cholesterol and apolipoprotein B levels (which are causal risk factors for heart disease). Common food sources include fatty meats, dairy foods, tallow/lard, coconut oil, palm oil, and cocoa.
Monounsaturated fats: In chemical terms, these are fatty acids that have one double bond between carbon atoms in the hydrocarbon chain. Compared to saturated fatty acids, monounsaturated fatty acids modestly reduce low-density lipoprotein cholesterol, triglycerides, and apolipoprotein B levels. Therefore, they’re considered heart healthy, and when replacing saturated fats in the diet, have been associated with a reduced risk of heart disease. Monounsaturated fatty acids are present in good quantities in most fat-containing foods; however, olive oil, avocados, and certain nuts and seeds are particularly high in monounsaturated fats.
Polyunsaturated fats: In chemical terms, these are fatty acids that have more than one double bond between carbon atoms in the hydrocarbon chain. Omega-6 and omega-3 fatty acids are subtypes of polyunsaturated fatty acids. Compared to saturated fatty acids, polyunsaturated fatty acids reduce low-density lipoprotein cholesterol, triglycerides, and apolipoprotein B levels. Therefore, they’re considered the most heart healthy fatty acid and, when replacing saturated fats in the diet, have been associated with a reduced risk of heart disease. Common food sources include vegetable oils, nuts, seeds, and oily fish (e.g., salmon, mackerel, sardines).