As humans, we derive energy from the foods we consume as these foods go through the digestive system within our bodies to be both broken down and made into usable energy for our most simple biological systems and processes. Every macronutrient (carbohydrates, proteins, and fats) plays an important role and provides various amounts of ATP. This transformed energy is then available for immediate use in the form of ATP. The ATP molecule is composed of three components (tri, meaning three). At the center is a sugar molecule (ribose) and attached are a string of three phosphate molecules (delineated as ‘P’ in the diagrams provided throughout this section).
During hydrolysis (breakdown) of ATP, an enzyme catalyzes the reaction when ATP joins with water. During the process, the outermost phosphate bond splits, releasing a considerable amount of free energy (which is then available for work). This energy can be used to build proteins, contract muscles, etc. Although this appears to be a laborious process, this occurs rapidly and does not require oxygen. The remaining molecule is adenosine diphosphate (ADP) because there are only two phosphate molecules remaining (di, meaning two).
ATP is both used and required by ALL cells in the body and also carries the potential energy to provide cells for use in the body as needed. As you can see, the connection between ATP and nutrition, also consider the same connection between ATP and muscular work – even just sitting upright in a chair requires that muscles work constantly, so the ability to maintain posture requires ATP. Taking things one step further, a physically active exerciser will need ATP in even greater amounts before, during and after each bout of exercise. It’s important to remember that during hydrolysis, the outermost phosphate bond is cleaved for all of this to be possible and the various metabolic pathways exist solely for the purpose of generating the appropriate amount of energy needed.
Energy from the macronutrients
Carbohydrates are preferred by the body as the main macronutrient source of energy. Carbohydrate is unique in that it is the only macronutrient that in its stored form, can be used for anaerobic metabolism of ATP. Carbohydrates are stored as glycogen in both the liver and muscles and liver Glycogen is easily converted to ATP; limited in supply, the need to replenish this energy source will be necessary upon normal stores being depleted. This translates to the type of food intake the individual follows -high carbohydrate or low carbohydrate – and therefore carbohydrate consumption also determines the level of glycogen storage. Higher carbohydrate intakes would allow for increased levels of glycogen storage, with the opposite being true for low carbohydrate diets.
Fat is another important macronutrient in human physiology. After carbohydrates stores have depleted, fat is then metabolized for ATP production. This aerobic type of metabolism can be on-going for extended bouts and as part of this design, there is always enough stored body fat in the body to tap into for ATP generation. In this process, the sources would be from adipose (fat) tissue and triglycerides stored within the muscle. While average carbohydrate reserves can provide about 2000 kcals for use yet fat renders nearly 50 times that amount. This is due in part to the energy density of fat, which means that each fat molecule provides up to 460 ATP, about 9 times that of carbohydrate energy totals. Fat metabolism also takes longer, as a process, by comparison to carbohydrate metabolism.
As a last resort, the body can turn to protein to make energy. Protein is tapped into when there are times of no food intake over extended periods. In times of carbohydrate restriction, protein is also used to make glucose for use – just as it is during extreme activity or physical activity bouts. As an inefﬁcient source of energy, proteins are amino acids that must be converted to usable forms of energy through more complex metabolic pathways.
Before protein can be used for energy, the nitrogen ‘backbone’ of the molecule must be removed. This deamination leaves a skeleton of carbon molecules behind that can then enter the Krebs cycle to be synthesized into a glucose molecule for energy. As stated, this is a complicated process and involves the actions of the liver to support gluconeogensis, as it is known.
What about alcohol? A lot of people consume liquor but are not aware of its nutritional proﬁle.
Alcohol is sometimes considered a nutrient because it does provide calories but its use is not appropriate either before (including the evening before), during, or immediately after activity or exercise. Alcohol should not be consumed above and beyond/over recommended amounts as it is not used as a major energy source during any activity. In some situations, consuming alcohol causes performance decrements because of its diuretic effects and due to its impact on liver function (glucose output is inﬂuenced by liver activity).
One signiﬁcant difference in the eating plan for an athlete is the timing of food intake or consumption. This could include making suggestions to your client on proper complex carbohydrate consumption prior to a bout of physical activity and/or simple carbohydrate consumption afterward. This basic nutrition information is what is expected to achieve results for your client, and to apply the principles of coaching, by relying on your science fundamentals and your speciﬁc knowledge of both macro and micronutrients. Remember, if you possess knowledge above a ‘basic’ level, you may engage your clients in dialogue about nutrition without fear of penalties.
Use caution when making suggestions about speciﬁc food choices and portions. You can certainly provide feedback about food choices made, or to explain to clients HOW to learn the difference between portions and servings from information provided on food labels. There are countless ways that you can strategize healthy eating options for ANY client, no matter what level of experience or circumstance – provided you are referring out clients when they present conditions outside of your normal scope.