Carbohydrate Requirements: 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 even involved in physical activities. The human body is like a machine, for a machine’s output it needs oil and other lubricants. Similarly, the human body needs the energy to keep the body parts moving.

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

Energy Sources

All we need energy, and it comes from different dietary sources like Carbohydrates, Protein, Fat, and Alcohol. We can collect energy in terms of calories and joules which is easily convertible into other units.

The basic fuel comes from muscle glycogen and fatty acids and main sources are carbohydrates and fat. In extreme circumstances, the body uses protein 5 -10 percent after the depletion of carbohydrates. 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 exercise. The storage capacity glycogen increases by increasing muscle mass, intensive training, and a CHO-rich diet. Energy comes from the substance in which famous ATP is very limited to the muscles.

Energy Measurements

One calorie is the amount of heat 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 need 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.

Read more: Muscle glycogen synthesis before and after exercise

Carbohydrates Requirements for a Human Body

The human body needs the energy to perform daily activities and carbohydrates are the best source to provide desired energy to a large extent. Body digest carbohydrates or use them to produce energy is stored in the form of glycogen or fat for upcoming events. The brain is dependents on glucose as a source of fuel along with the working muscles during more complex exercises. Carbohydrates’ requirements are different in people because of their physical activities and working hours, etc. Similarly, athletes’ needs of carbohydrates are compared to the average person. Without having a large number 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 like

  • Monosaccharides (Fructose, Glucose, Galactose), (mono = one, saccharide = sugar) (a simple carbohydrate) glucose – commonly known 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 like 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

  • Continuous aerobic exercises
  • Intermittent aerobic exercises
  • High-intensity aerobic exercise

Carbohydrates requirements to athletes

Carbohydrates requirements for an athlete consist of these factors

  • Intensity
  • Durations
  • Fitness Level
  • Nutritional Status

Without appropriate 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 effects on health.

Grams of CHO/kg body weight per day

Example: Carbohydrates Requirements

MR A, Age 28, Weight 90, and 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.

Activity Level 3-5 Hours/week 5-7 Hours/week 1-2


2-4 Hours/day >4

Hours/ day

Carbohydrate Requirements 5 gram 5-6 gram 6-7 gram 7-8 gram 8-10 gram


  • 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:

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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