Energy represents the capacity to do work, and the human source of energy is FOOD. A calorie is the standard measure of energy. The amount of energy expended depends on the duration and type of activity.
Carbohydrates and fats are primary energy nutrients.
Protein can become a source of energy but to a limited extent. Protein is however, essential for growth and repair of muscle and body tissues.
Fat not only is important in relation to fat-soluble vitamins, but it is also essential as an energy source for low to moderate intensity exercise. Carbohydrate is the optimal energy for high intensity aerobic and anaerobic exercise. For optimal performance, an athlete should eat a calculated balance of macronutrient and micronutrients. (Macronutrients are carbohydrates, proteins and fats, and micronutrients are vitamins and minerals.) Vitamins and minerals are elements critical for chemical processes in the body and thus for normal human functioning. The fibrous indigestible portion of food, called fiber, is also essential for a healthy digestive system. Last but not least, water! Water, is essential as a vehicle for carrying other nutrients.
Calculating your Individual Energy Needs
A simplistic calculation can help determine an estimate of energy required for an athlete.
Energy required = Resting energy Expenditure (REE) (basically what your body needs just to function) + physical activity requirements.
To calculate an estimate of REE:
For every kilogram of body weight, an athlete requires approximately 1.3 calories per hour. For example:
An athlete weighing 60 Kg would require 1.3 x 24 hrs x 70 Kg = approx 1872 calories.
To calculate physical activity requirements:
For every hour of activity, 8.5 calories is required kilogram of body weight. For example: For 2 hours of training, a 60 kg athlete requires 8.5 x 2 (hours) x 60 (kg of body weight) = 1020 calories Thus an athlete weighing 60Kg, who trains for two hours, would require an intake of approx: 1870 + 1020 calories = 2890 calories (approx 3000 calories rounded up)
The Optimal Breakdown of Nutrients for Athletes
Like fuel for a car, energy from food also has an optimal blend. The blend for an athlete may depend on the type of sport s/he is involved in, however, in general: 55-60% of energy should be from carbs. Glycogen is the main source of energy used by the muscles to enable you to undertake both aerobic and anaerobic exercise. Most ingested carbohydrates are initially converted to blood glucose and used for energy or stored as glycogen, but excess may be stored as fat. Blood glucose is essential for optimal functioning of the nervous system, whereas muscle glycogen is essential for endurance exercise. Low levels of glucose or muscle glycogen may be contributing factors in the early onset of fatigue, in other words, training with low glycogen stores will result in a constant feeling of tiredness, a lowering of training performance and an increased risk for injury and illness. 25 – 30% of energy should be from fats. One of the main functions of fat is to provide energy. In general a low-fat diet is recommended for both health and physical performance. An athlete should consume less high fat meats and dairy products and more fruits, vegetables and whole grains, dietary fiber, lean meats, and nonfat dairy. 20 – 25 % of energy should be from protein. The major function of protein is to repair and build tissues and to synthesize hormones, enzymes, and other body components. Protein may be used as a source of energy under certain conditions, such as intense exercise during low carbohydrate stores. Although some athletes may benefit from additional protein, they do not need expensive commercial protein supplements, instead they should obtain the extra protein from increased caloric intake of food associated with their physical activity requirements.
The 60kg athlete would then calculate his daily requirements as follows:
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Carbs – 55% of 3000 = 1650 calories – at 4 kcal per gram = 1650 /4 = 412.5 g |
There are 4 calories per gram of carbs |
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Protein – 20% of3000 = 600 calories – at 4 kcal per gram = 600 / 4 = 150 g |
There are 4 calories per gram of protein |
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Fats – 25% of 3000 = 750 calories – at 9 kcal per gram = 750 / 9 = 83 g |
There are 9 calories per gram of fat |
In Summary
Nutrient balance is critical to good health and performance. The athlete’s goal should be to find the appropriate balance between all the nutrients, since too much or too little of any one nutrient will cause health and/or performance problems. For instance, too little iron intake would lead to poor endurance and lower ability to burn fat, while too much protein could increase urine production and increase the risk of dehydration. The best strategy for maintaining a nutrient balance is to eat a wide variety of foods, regularly consume fresh fruits and vegetables, and avoid a monotonous intake of the same few foods day after day.
The easiest way to assure optimal nutrient exposure is to consume a wide variety of foods. No single food has all the nutrients a person needs to stay healthy so eating a wide variety of foods helps people know that all the needed nutrients are available to them. An added benefit of eating a wide variety of foods is avoidance of nutrient toxicities, which result from excess vitamin and mineral intake.
