How Your Body Uses Food for Energy


The bodies first most readily useable fuel source is glucose which is stored in the muscles and the liver in a form called glycogen. During exercise the amount of glycogen available to be transformed into glucose is a key factor in stamina and strength. With a deficiency of glycogen you will quickly feel fatigued. A high-intensity workout is only possible when glycogen is readily available in adequate amounts for your sports nutrition health.



The bodies second most useable dietary source of fuel is carbohydrates. These are easily broken down into glucose molecules and then used to fuel the body during physical exercise. If they are not used after ingestion then they will be stored as glycogen within the liver until it is needed. Many serious athletes will eat large amounts of carbohydrates several days before an event in order to get their glycogen stores filled so they perform with maximum endurance and strength. Focussed athletes know sports nutrition health and how to achieve their best performance. Sources of quality carbohydrates include: soybeans, kidney beans, lentils, sweet potatoes, apples, oranges, whole wheat products, brown rice. Try to eat more fructose filled foods than any other sugar (word ending with ‘ose’) as well as try to stick to a diet filled with slowly digested carbohydrates, this prevents spikes in blood glucose levels.


Fat’s and Lipids

Once glucose, glycogen and carbohydrates have been exhausted the body turns to body fat as a fuel source (not dietary fat breakdown, body fat!). Generally speaking, after 20 minutes of aerobic exercise the body starts to burn fat stored within the body. Diet’s high in fat are a poor way to increase performance as the fat being ingested will not necessarily be burned during exercise. Sources of quality ‘good fat’ includes: fish (not shell fish), extra virgin olive oil (organic), flax seed oil, hemp seed oil, linseed oil, pumpkin seeds, walnuts and soybeans. Try to use long chain fats as they make up most of the human brain. Unsaturated fats are much more biologically active then saturated fats and should be eaten daily for optimum sports nutrition health.



If these general fuels are in short supply the body turns to breaking down and converting our own muscles protein into glucose for an energy source. When this breaking down of our own lean mass occurs, we build up toxic levels of ammonia decreasing the effectiveness of our workout. Sufficient protein must be included with quality sources and efficient amounts in order to repair our damaged tissues as well as replace any protein being converted for fuel. Generally try to eat high qulity, organic, low fat proteins. When choosing protein supplements for sports nutrition health the most easily absorbed and high quality supplement is Whey! Choose pre-digested proteins which contain high levels of leucine and valine (40 mg per kg of body weight).


When excessive carbohydrates are taken into the body that increase the demand of energy needed, these carbohydrates are converted into fat and stored until burned at a later date (if ever!). This is not good sports nutrition or healthy.


References: Prescription for Nutritional Healing Second Edition

James F. Balch, Phyllis A. Balch Avery Publishing Corp. 1997


Choosing Energy Drinks

By Monique Ryan, MS, RD

It can be difficult to sift through all the different "oses" that are out there and other sports drink ingredients. Sports drinks provide fluid, electrolytes, and of course carbohydrate. For this week's Q&A, we can consider the type of carbohydrate that is being consumed as it relates to the two questions above. As was discussed last week's column, carbohydrates that have a moderate to high glycemic index provide a rapid increase in blood glucose levels and can be effectively used by the muscles as a fuel source. You do not have to consume glucose in a drink to raise your blood glucose levels. Some commonly seen carbohydrate sources are glucose, sucrose, fructose, glucose polymers or maltodextrin (short chains of glucose molecules). Maltose is simply two linked glucose molecules. Research has shown that all these carbohydrates, when consumed in the 6 to 8 percent carbohydrate concentration (the range for the vast majority of sports drinks), are well absorbed and utilized by the muscle for energy. Using more than one type of carbohydrate source allows manufacturers to work with various textures and taste combinations, so that these drinks are as palatable as possible. It might also be of benefit to have various types of carbohydrates in a drink, as they all use slightly different transport mechanisms when being absorbed across the small intestine. This just means that the carbohydrates get into your blood stream more quickly and provide fuel for your muscles more quickly. Generally, it is advisable to avoid sports drinks in which fructose is the only ingredient, as this may cause gastrointestinal upset in some individuals. Fructose is often one of two ingredients in a sports drink, and should be well tolerated in this type of formulation. So what is the best sports drink for you to use? The one which you can tolerate at a full concentration (for the full performance benefit related to carbohydrate), and which you like (so that you will drink enough). Drinks containing glucose polymers may taste less sweet, whereas some endurance athletes may prefer a sweeter taste. Keep in mind that you have to drink plenty, as the recommended amounts are 4 to 8 ounces every 15 to 20 minutes. It can be challenging for some athletes to find the sports drink that works best for them, so keep trying various products and flavors which may contain any variety of carbohydrate ingredients to determine which one works best for you.