Carbohydrates, protein, and fat ultimately provide the energy necessary to maintain our body’s functions during both rest, and physical activity (1), and consequently maintain its structural and functional integrity.
However, over the years’ macronutrients have been interchangeably used in various amounts, types, and periodization throughout our diets with some uncertainty; carbohydrates, or carbs, as they are typically known have gone from the ‘all you can eat!’ good guy, to the ‘carbs make you fat!’ bad guy, and now are seen as the King of fuelling substrates when periodized correctly.
Protein, by many athletes is still quite misunderstood, and a wary sort of nutrient, because of the arcane and bad dietary stigma attached to the overconsumption of essential amino acids and, ill- health.
Finally, the nutrient of fat…this potential energy releasing powerhouse should not be under estimated as a key macronutrient for health and performance. Fat should not be under consumed (neither should it be over consumed).
Carbohydrates are the ultimate fuel for your body and your brain (2). There are two classifications of carbohydrate; simple and complex. Both differ structurally, with simple carbohydrates made up of short chains of sugars (monosaccharides, disaccharides, and, oligosaccharides). Complex carbohydrates are constructed of longer chains of sugars (polysaccharides) and include starch and fiber.
Simple carbohydrates include sugars such as glucose, fructose, galactose, sucrose, and, maltodextrins and range from one single molecule up to 9 molecules, making them the easiest carbohydrates to digest and to utilize during exercise. Complex carbohydrates are constructed of long, complex chains and require a much more multifaceted utilization journey, making their digestion time significantly longer than simple carbohydrates.
Carbohydrates are contained in all living cells and we ingest the majority of them through plant sources, where they are then metabolised via a process called glycolysis (the breakdown of glucose to form adenosine triphosphate [ATP], or energy). Though energy is its main role, carbohydrate has several other roles including storing energy as glycogen, and also converting glucose into fat to store. For many years, nutritional considerations for endurance athletes have always suggested greater amounts of carbohydrates be consumed before exercise to help maximise endogenous glycogen stores (3) and to also maintain serum glucose levels throughout training (4,5). As the body, can only store 500-600g (~2000Kcals/2-4hrs of moderate-high intensity exercise) of total carbohydrate at any one time this energy store needs to be replenished throughout endurance events and training to keep performance at an optimum level. Throughout scientific literature, it is suggested that 1-1.1g/CHO/min or 60g/hr can be oxidized by the body, whether this is via solid food, liquids, or energy gels/bars (6).
The Glycemic Response (GR) of different foods is a measure of its ability to raise blood sugar, and is a key factor when considering digestion times of food. Many individuals have adopted the use of the Glycemic Index (GI) and Glycemic Load (GL) of carbohydrates as part of their training, therefore the importance of the Glycemic Response, Glycemic Index, and Glycemic Load, and how to use them will be discussed in a future article.
Muscle repair and recovery is vital to athletes to help optimize training and performance, and this is increased by the consumption of protein-rich foods. Protein has an array of cellular functions such as catalytic (enzymes), transport & storage (haemoglobin), endocrine releasing proteins such as insulin, signalling kinases, contractile proteins (actin and myosin), structural (dystrophin), immunological antibodies, and regulatory proteins known as transcription factors. Among the current literature, protein recommendations range from 1.2-2.0g/kg of body weight/day. This is to support metabolic adaptations, muscle repair & remodelling, and for protein turnover (7).
Proteins are categorized as essential and non-essential. By way of definition essential proteins, or amino acids (AA) are those which need to be obtained through the food we eat, as the body cannot manufacture them. Whereas non-essential amino acids can be made by the body.
For all cellular functions to be carried out it takes hundreds of thousands of individual proteins, each with their own unique role to make everything run smoothly to optimize a healthy life-style and performance. If just one of these proteins is insufficient in any way, such as the patients of McArdle’s syndrome who cannot break down glycogen stores in to energy, this can have devastating effects, not only on performance but on health and everyday well-being.
Proteins are the cellular action molecules as they perform vital maintenance functions, and should, depending on training loads and intensities, make up ~10-20% of your total daily Kcals.
Fats, or to give them their scientific Sunday name, Lipids are a group of nutrients which are broken in to categories (saturated and unsaturated), and unsaturated sub-categories (monounsaturated, polyunsaturated, and, trans fats).
Fat is a major source of energy in our body, especially during low to moderate aerobic activity (8), and between bouts of high-intensity training (9). As a result of endurance training this source of energy, in the form of free fatty acids (FFA), intramuscular triglycerides, and adipose tissue provides increased availability and also a near infinite supply of energy (~80,000Kcals). Other than an energy source, lipids also play a vital role in body temperature regulation, the protection of organs, vitamin distribution, and aid in cell membrane construction (10).
With regards to an energy source, fat is an ideal fuel, especially for the ultra-endurance athlete, as it is easily stored and transported, light-weight, and packs a double punch of energy (compared to glucose), however, many individuals, such as athletes never realise the full potential of being able to tap in to such an energy reservoir as our fat stores during training, and competitions, such as ultra-marathons, adventure races, and Iron-man events.
- Macronutrients, ultimately provide the energy necessary to maintain the body’s functions during rest, and physical activity
- Carbohydrates are the ultimate fuel for your body and your brain
- Proteins are the cellular action molecules as they perform vital maintenance functions throughout the body
- Fat is a major source of energy in our body, especially during low to moderate aerobic activity
- All three macronutrients will combine to help meet the energy demands of the body for survival, and performance
Carbohydrates, protein, and fats to some extent will work, and combine with one another to be able to meet the energy demands of the human body. Being able to optimize nutrition includes the adequate intake of both, quality, and, quantity of food and fluids to be able to provide the essential nutrients for both, survival, and performance (1).
In subsequent articles, macronutrients will be discussed in much further detail, and on an individual basis.
Next Time: Understanding Carbohydrates ‘The Substrate King’
1– Hofheins, J. (2013). Essentials of Sports Nutrition and Supplements: An Overview of Macronutrients. NJ, USA, Humana Press
2– Seebohar, B. (2011). Nutrition Periodization for Athletes. (Second Ed.) CO, USA, Bull Publishing Company
3– Kerksisck, C; Harvey, T; Stout, J; Campbell, B; Wilborn, C; Kreider, R; Kalman, D; Ziegenfuss, T; Lopez, H; Landis, J; Ivu, J.L and Antonio, J. International Society of Sports Nutrition Position Stand: Nutrient Timing. JISSN. 5:17 (2008)
4– Kavouras, S.A; Troup, J.P and Berning, J.R. The Influence of Low versus High Carbohydrate Diet on a 45-minute Strenuous Cycling Exercise. Int. J. Sport Nutrition & Ex. Met. 14, 62-72 (2004)
5– Coyle, E.F; Coggan, A.R and Hemmert, M.K. Muscle Glycogen Utilization during Prolonged Strenuous Exercise When Fed Carbohydrate. J. Appl. Phys. 61. 165-172 (1986)
6– Kreider, R.B; Wilborn, C.D; Taylor, L; Campbell, B; Almada, A.L; Collins, R; Cooke, M; Earnest, C.P; Greenwood, M; Kalman, D.S; Kerksick1, C.M; Kleiner, S.M; Leutholtz, B; Lopez, H; Lowery, L.M; Mendel, R; Smith, A; Spano, M; Wildman, R; Willoughby, D.S; Ziegenfuss, T.N and Antonio, J. ISSN Exercise & Sport Nutrition Review: Research & Recommendations. Journal of the International Society of Sports Nutrition. 7:7 (2010)
7– Thomas, D.T., Erdman, K. A. and Burke, L.M. Position of the Academy of Nutrition & Dietetics, Dietitians of Canada and the American College of Sports Medicine: Nutrition and Athletic Performance. Journal Academy of Nutrition & Dietetics. 116 (3) 501-528 (2016)
8– Gilmore, P.L. (2010). Lipids: Categories, Biological Functions and Metabolism, Nutrition & Health. New York, USA, Nova Science Publishers Inc.
9– MacLaren, D and Morton, J. (2012). The Biochemistry for Sport and Exercise Metabolism. Oxford, UK, Wiley-Blackwell
10– Currell, K. (2016) Performance Nutrition. Wiltshire, UK, Crowood