Macronutrient: a substance required in relatively large amounts by living organisms.
How Does Food Provide Energy?
Energy, being the capacity to do work, is the reason why we eat food. Carboydrates, proteins and fats all contain chemical energy that is able to be harnessed. Cells in the body are able to transfer energyfrom these macronutrients into adenosine triphosphate (ATP). The body then uses ATP to power many physiological processes. While vitamins and minerals are required for producing energy and regulating chemical reactions, they alone do not yield energy.
Energy within food is measured in units known as calories. A calorie is defined as the amount of heat required to raise the temperature of 1 gram of water 1 degree Celsius. The more calories food contains, the more ATP the body can yield. Since 1 calorie represents a very small amount of energy, the energy content of foods is commonly expressed in units of kilocalories, or 1000 calories, often referred as "kcal" or "C". Thus, 1 Calorie is eqivalent to 1000 calories or 1 kcal.
Energy within food is measured in units known as calories. A calorie is defined as the amount of heat required to raise the temperature of 1 gram of water 1 degree Celsius. The more calories food contains, the more ATP the body can yield. Since 1 calorie represents a very small amount of energy, the energy content of foods is commonly expressed in units of kilocalories, or 1000 calories, often referred as "kcal" or "C". Thus, 1 Calorie is eqivalent to 1000 calories or 1 kcal.
Alcohol, albeit not a nutrient, provides approximately 7 kcal/gram
With these caloric values, the percentage of each energy-yielding macronutrient—carbohydrates, proteins and fats—can be calculated by the amount found of the food label, simply by multiplying the weight of each macronutrient by its caloric value (McGuire, Beerman, & William, 2011).
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For example, consider this food label. For each serving, there are 15 grams of fat, 30 grams of carbohydrates and 5 grams of protein. This is equivalent to:
Therefore, this food provides 49%, 44%, and 7% of its energy from fats, carbohydrates and proteins, respectively. |
Image by John Hopkins Medicine
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Balancing Macronutrients
According to the National Academies of Sciences, it is currently recommended that 45-65% of energy is supplied from carbohydrates, 10-35% from proteins and 20-35% from fats (McGuire, Beerman, & William, 2011). However, this general guideline may not be the healthiest for everyone, since everyone is different. In fact there are several other ratios, each with a set of pros and cons.
Macronutrients and Bone
In order to bone formation to occur, it must require the appropriate nutrients. As noted previously, osteoid, the organic portion of bone, is mainly type 1 collagen, but also includes bone cells (osteoblasts, osteoclasts and osteocytes). Osteoblasts can only create osteoid, which is mainly collagen, with the appropriate macronutrients and micronutrients. Let's begin with macronutrients- protein, fat , carbohydrates.
Carbohydrates are that been refined are known to affect bone growth and strength negatively. Research conducted on animals suggests that the breaking strength of tibiae and femurs significantly reduced in the sucrose-fed group compared to the control group. Similar research found a significantly lower strength and quality of bone, in those fed a diet high in sucrose and saturated fat. A significant decrease of bone mineral density was associated with consumption of carbonated soft drinks. Sports drinks, such as Gatorade or Powerade, commonly contain high-fructose corn syrup (HFCS)-55, which contains 42% fructose and 58% glucose. These sports drinks are suggested to negatively affect the skeleton, compared to the consumption of fluids without glucose, such as water. Complex carbohydrates, found in fruits and vegetables have been found to increase calcium absorption, increasing skeletal growth (Lorincz, Manske, & Zernicke, 2009). Good sources of complex carbohydrates include potatoes, beans and lentils.
Dietary protein is essential for maintaining optimal bone health as proteins make up a large component of the organic matrix, proteins also regulate the concentration of insulin-like growth factors (proteins that communicate with the body), and proteins also affect calcium absorption and excretion (Lorincz, Manske, & Zernicke, 2009). The current recommended intake for dietary protein is at least 0.8 g/kg, as intakes below this level are associated with reduction in calcium absorption (Kerstetter, O’Brien, & Insogna, 2003). Good sources of protein include chicken, turkey, tuna, soybeans, salmon, beef, shrimp, salmon, and sardines (Mateljan, 2001).
Carbohydrates are that been refined are known to affect bone growth and strength negatively. Research conducted on animals suggests that the breaking strength of tibiae and femurs significantly reduced in the sucrose-fed group compared to the control group. Similar research found a significantly lower strength and quality of bone, in those fed a diet high in sucrose and saturated fat. A significant decrease of bone mineral density was associated with consumption of carbonated soft drinks. Sports drinks, such as Gatorade or Powerade, commonly contain high-fructose corn syrup (HFCS)-55, which contains 42% fructose and 58% glucose. These sports drinks are suggested to negatively affect the skeleton, compared to the consumption of fluids without glucose, such as water. Complex carbohydrates, found in fruits and vegetables have been found to increase calcium absorption, increasing skeletal growth (Lorincz, Manske, & Zernicke, 2009). Good sources of complex carbohydrates include potatoes, beans and lentils.
Dietary protein is essential for maintaining optimal bone health as proteins make up a large component of the organic matrix, proteins also regulate the concentration of insulin-like growth factors (proteins that communicate with the body), and proteins also affect calcium absorption and excretion (Lorincz, Manske, & Zernicke, 2009). The current recommended intake for dietary protein is at least 0.8 g/kg, as intakes below this level are associated with reduction in calcium absorption (Kerstetter, O’Brien, & Insogna, 2003). Good sources of protein include chicken, turkey, tuna, soybeans, salmon, beef, shrimp, salmon, and sardines (Mateljan, 2001).
There are several types of fat, saturated, unsaturated, polyunsaturated and trans fat. Research conducted in animals suggests that calcium absorption decreases as saturated fat content increases. Similar results conducted in humans found a negative correlation between consumption of saturated fat and hip bone mineral density (BMD) in both men and women, affecting men to a higher degree (Lorincz, Manske, & Zernicke, 2009). The current Acceptable Macronutrient Distribution Range (AMDR) set by the National Academy of Sciences estimates that total fat intake should consist of 20-35% of total caloric intake (Lupton et al., 2005). Research on the consumption of polyunsaturated fat, such as omega-3 fatty acids, is associated with a promotion of bone formation and a significantly higher BMD (Lorincz, Manske, & Zernicke, 2009). Monounsaturated fats are linked with a lower risk of developing cardiovascular disease, certain types of cancer, and rheumatoid arthritis. Good sources of monounsaturated fat include olive oil, avocados, almonds and cashews (Mateljan, 2001).
Macronutrients and Muscle
The caloric requirements that muscle needs in order to initiate contraction is provided via macronutrients. It is crucial that every individual, especially athletes obtain enough calories to meet the demands placed on the body. A well balanced, nutrient dense diet is encouraged to optimize training and performance.
Carbohydrates are necessary to maintain glycogen levels within the muscle and liver. Glycogen is a polysaccharide that functions as a main storage of glucose, which can then be used as energy throughout the body. Carbohydrates are the preferred fuel source during intense training. Research suggests complex carbohydrates with a low to moderate glycemic index are preferred. 3-5 grams of carbohydrates per kg of body weight of is considered a normal macronutrutrient range, although athletes involved in high intensity training should consume 8-10 g/day to maintain glycogen levels (Kreider et al., 2010).
Given that the very functional capabilities of muscle rely on a cascading symbiotic effect of structural and contractile proteins, which are composed of amino acids, it would be safe to say that protein is crucial for muscle development and growth. An adequate amount of quality protein is essential in maintaining muscle mass. Too little protein results in a negative nitrogen balance, which is a greater loss of nitrogen that intake, an undesirable state for athletes. On the other hand, high-protein diets are not a safe method for building muscle either. A mechanism that causes the method to be unsafe lies within the physiology of breaking down proteins. As an individual consumes more protein than needed, the body enters a positive nitrogen balance therefore the body must remove more nitrogen waste products from the blood, subsequently placing excess stress on the kidneys. According to research conducted on endurance athletes, a possible result of excess protein consumption is chronic dehydration. Dehydration can significantly alter exercise performance and can lead to musculoskeletal injuries or environmental disorders, such as heat stress or heat stroke, all of which are not safe for building muscle. This study suggests that dietary protein intake should not exceed 1.6 grams/kg of body weight/day (Tarnopolsky, 2004). While the RDA for protein is 0.8 g/kg, research suggests protein intake for athletes should range from 1.5-2.0 g/kg to maintain protein balance. The best sources of high quality protein are chicken, fish, egg whites and whey protein (Kreider et al., 2010).
Fats, or triglycerides, are an important source of fuel for prolonged exercise, however in order to utilize fats, carbohydrates be consumed. It is recommended that approximately 30% of an athlete's daily caloric intake should be provided by fats. High volume athletes can increase fat intake up to 50% of total calories. More research needs to be conducted on whether medium-chain triglycerides, a fatty acid that is easily digested, rapidly absorbed and transported in mitochondria, is an effective performance enhancement (Kreider et al., 2010).
Carbohydrates are necessary to maintain glycogen levels within the muscle and liver. Glycogen is a polysaccharide that functions as a main storage of glucose, which can then be used as energy throughout the body. Carbohydrates are the preferred fuel source during intense training. Research suggests complex carbohydrates with a low to moderate glycemic index are preferred. 3-5 grams of carbohydrates per kg of body weight of is considered a normal macronutrutrient range, although athletes involved in high intensity training should consume 8-10 g/day to maintain glycogen levels (Kreider et al., 2010).
Given that the very functional capabilities of muscle rely on a cascading symbiotic effect of structural and contractile proteins, which are composed of amino acids, it would be safe to say that protein is crucial for muscle development and growth. An adequate amount of quality protein is essential in maintaining muscle mass. Too little protein results in a negative nitrogen balance, which is a greater loss of nitrogen that intake, an undesirable state for athletes. On the other hand, high-protein diets are not a safe method for building muscle either. A mechanism that causes the method to be unsafe lies within the physiology of breaking down proteins. As an individual consumes more protein than needed, the body enters a positive nitrogen balance therefore the body must remove more nitrogen waste products from the blood, subsequently placing excess stress on the kidneys. According to research conducted on endurance athletes, a possible result of excess protein consumption is chronic dehydration. Dehydration can significantly alter exercise performance and can lead to musculoskeletal injuries or environmental disorders, such as heat stress or heat stroke, all of which are not safe for building muscle. This study suggests that dietary protein intake should not exceed 1.6 grams/kg of body weight/day (Tarnopolsky, 2004). While the RDA for protein is 0.8 g/kg, research suggests protein intake for athletes should range from 1.5-2.0 g/kg to maintain protein balance. The best sources of high quality protein are chicken, fish, egg whites and whey protein (Kreider et al., 2010).
Fats, or triglycerides, are an important source of fuel for prolonged exercise, however in order to utilize fats, carbohydrates be consumed. It is recommended that approximately 30% of an athlete's daily caloric intake should be provided by fats. High volume athletes can increase fat intake up to 50% of total calories. More research needs to be conducted on whether medium-chain triglycerides, a fatty acid that is easily digested, rapidly absorbed and transported in mitochondria, is an effective performance enhancement (Kreider et al., 2010).
References
Kerstetter, J., O’Brien, K., & Insogna, K. (2003, September ). Dietary protein, calcium metabolism, and skeletal homeostasis revisited. Retrieved December 1, 2016, from The American Journal of Clincal Nutrition, http://ajcn.nutrition.org/content/78/3/584S.full
Kreider, R. B., Wilborn, C. D., Taylor, L., Campbell, B., Almada, A. L., Collins, R., … Antonio, J. (2010). ISSN exercise & sport nutrition review: Research & recommendations. Journal of the International Society of Sports Nutrition, 7(1), 7. doi:10.1186/1550-2783-7-7
Lorincz, C., Manske, S. L., & Zernicke, R. (2009). Bone health. , 1(3), . Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3445243/
Lupton, J., Brooks, G., Butte, N., Caballero, B., Flatt, J., Fried, S., … Jenkins, D. (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Retrieved December 1, 2016, from The National Academise Press, https://www.nap.edu/read/10490/chapter/10
Mateljan, G. (2001). A new way of looking at proteins, fats and Carbohydrates. Retrieved December 1, 2016, from The World’s Healthiest Foods, http://whfoods.com/genpage.php?tname=faq&dbid=7#health
Mateljan, G. (2001). Protein. Retrieved December 1, 2016, from The World’s Healiest Foods, http://whfoods.com/genpage.php?tname=nutrient&dbid=92
McGuire, M., Beerman, K. A., & William, M. (2011). Nutritional sciences: From fundamentals to food (with table of food composition booklet) (3rd ed.). Boston, MA, United States: Wadsworth, Cengage Learning.
Tarnopolsky, M. (2004, April). Protein Requirements for Endurance Athletes. Retrieved October 20, 2016, from https://www.uscupstate.edu/uploadedFiles/Student_Affairs/Health_Promotion_and_Education/Protein II.pdf
Kreider, R. B., Wilborn, C. D., Taylor, L., Campbell, B., Almada, A. L., Collins, R., … Antonio, J. (2010). ISSN exercise & sport nutrition review: Research & recommendations. Journal of the International Society of Sports Nutrition, 7(1), 7. doi:10.1186/1550-2783-7-7
Lorincz, C., Manske, S. L., & Zernicke, R. (2009). Bone health. , 1(3), . Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3445243/
Lupton, J., Brooks, G., Butte, N., Caballero, B., Flatt, J., Fried, S., … Jenkins, D. (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Retrieved December 1, 2016, from The National Academise Press, https://www.nap.edu/read/10490/chapter/10
Mateljan, G. (2001). A new way of looking at proteins, fats and Carbohydrates. Retrieved December 1, 2016, from The World’s Healthiest Foods, http://whfoods.com/genpage.php?tname=faq&dbid=7#health
Mateljan, G. (2001). Protein. Retrieved December 1, 2016, from The World’s Healiest Foods, http://whfoods.com/genpage.php?tname=nutrient&dbid=92
McGuire, M., Beerman, K. A., & William, M. (2011). Nutritional sciences: From fundamentals to food (with table of food composition booklet) (3rd ed.). Boston, MA, United States: Wadsworth, Cengage Learning.
Tarnopolsky, M. (2004, April). Protein Requirements for Endurance Athletes. Retrieved October 20, 2016, from https://www.uscupstate.edu/uploadedFiles/Student_Affairs/Health_Promotion_and_Education/Protein II.pdf
