Importance of Energy for Human Body

Energy for Human Body

Energy is the ability to do work, and it works in 3 different ways. All human being needs it though if they are not involved in any physical activities. The human body is like a machine, for a machine’s greater efficiency it needs oil and other lubricants. Similarly, the human body also requires it to keep body parts moving and remain healthy.

  • Chemical work (Building cells components)
  • Transport work (Substance among cells)
  • Mechanical work (Muscle construction)

Energy Sources

Everybody needs energy, and it comes from different dietary sources such as Carbohydrates, Protein, Fat and Alcohol. We measure it in terms of calories and joules and easily convertible into any other unit.

The primary body fuel for athletic activities is muscle glycogen and fatty acids which come in the form of carbohydrates and fat. In extreme circumstances such as carbohydrates, the depletion body uses protein 5 -10 percent. Storage Division, The total storage of glycogen, is 500g in which 400g stores in muscles and 100g in the liver that is enough for 2 hours of high-intensity exercises. The storage capacity of glycogen increases by increasing muscle mass, intensive training, and a CHO-rich diet. Energy comes from the substance known as ATP it is very limited to the muscles and remains for 1-2 sec.

Energy Measurements

One calorie is the amount of heat needed to raise the temperature of 1 gm of water by one centigrade. A calorie is a smaller unit hence kcal is commonly used. Number of calories for the energy sources

  • Carbohydrates, 1g = 4 calories
  • Protein, 1g = 4 calories
  • Fat, 1g = 9 calories
  • Alcohol, 1g = 7calories

Energy Systems

There are three energy systems that work together to provide energy.

  • Creatine Phosphate (phosphocreatine/up/anaerobic lactate) this system does not require oxygen, fat, and carbohydrates but infects the use of chemical energy.
  • Lactate (anaerobic glycolysis) refers to the conversion of glucose to lactic acid.
  • The aerobic (oxidative) energy system that produces ATP from the complete breakdown of carbohydrates and fat in the presence of O2.

Carbohydrates Requirements for a Human Body

The human body needs the energy to perform daily base activities, and carbohydrates are the best source to provide desired energy to a greater extent. Body digest carbohydrates or use them to produce energy and excess is stored in the form of glycogen or fat for upcoming events. The brain is also dependent on glucose as a source of fuel along with the working muscles during more intensive exercises. Carbohydrates’ requirements for individuals differently because of their physical activities, gender, working hours, etc. Similarly, athletes’ needs of carbohydrates are more as compared to the average person. Without having a sufficient amount of carbohydrates, their bodies can’t perform efficiently. The lack of energy may cause fatigue in the muscles.

Types of Carbohydrates

The body can get energy from different kinds of carbohydrates such as

  • Monosaccharides (Fructose, Glucose, Galactose), (mono = one, saccharide = sugar) (a simple carbohydrate) glucose – commonly referred to as “blood sugar” galactose – sugar in milk fructose – sugar in fruit.
  • Disaccharides (Citrus Fruits, Maltose), (di = two, saccharide = sugar) (simple carbohydrate) sucrose – table sugar; a combination of glucose + fructose lactose – milk sugar; combination of glucose + galactose.
  • Oligosaccharides (Dietary Sources, Vegetables, Onions, Leeks, Garlic)
  • Polysaccharides (Starchy Foods such as Bread, Pasta, and many Vegetables),(No Starch or Fiber), (poly = many, saccharide = sugar) (complex carbohydrate) starch fiber.

Benefits of using Carbohydrates

Furthermore, the availability of Carbohydrates influences

  • Continuous aerobic activities
  • Intermittent aerobic activities
  • High-intensity anaerobic activities
  • Carbohydrates requirements to athletes

Carbohydrates requirements for athletes depend on these factors

Without adequate intake of carbohydrates will have a negative impact on health (physical and mental fatigue), exercise performance, recovery and training adoption. 60 percent of energy should come from carbohydrates if you want to get rid of adverse impacts on health.

Grams of CHO/kg body weight per day

Activity Level ( Moderate intensity)
3-5 hours per week 5 g 5-7 hours per week 5-6 g 1-2 hours per day 6-7 g 2-4 hours per day 7-8 g More than 4 hours per day 8-10 g

Example: Carbohydrates Requirements

MR A,  Age 28, Weight 90, Exercise 6 days in a week: 2 hours daily workout includes 1-hour weight training, 1 hour includes half an hour cardio that includes 10 minutes rowing, 10 min step raise, 10 min cycling, and half an hour abs exercise.


  • His total intake of CHO is 90 * 7=630
  • Before exercise 2-4 hours  90*2.5=225
  • Exercise more than 1-hour additional 70 g is required
  • Up to hours, post-CHO need
  • 90*2=180
  • Total CHO before during and after is 225+70+180=475
  • Remaining
  • 630-475=155 throughout a day.

Let’s take another example:

Here we already calculated daily calories need for a 200-pound athlete.

Example: Male, 200 lbs, 15% body fat, competitive athlete
3420 daily calories – 581 fat calories – 1120 protein calories = 1719 carbohydrate calories
1719 carbohydrate calories ÷ 4 calories per gram (as indicated on the caloric density chart) = 430 grams of carbohydrates per day
To determine the percentage of calories that come from carbohydrates simply divide the number of carbohydrate calories by the number of overall calories
1719 carbohydrate calories ÷ 3420 overall calories = 50%
50% of the overall calories are derived from carbohydrates.

Hence, a 200-pound adult male athlete is eating a calorie ratio of 17% fat, 33% protein, and 50% carbohydrates.

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