25.10.2021

Metabolism

What is metabolism?

Energy metabolism

① Basal metabolic rate

② Resting metabolic rate

③ Metabolism during physical activities

Energy requirements

Atwater system

What is metabolism?

Metabolism is the process of utilizing the ingested nutrients in the body to excrete unnecessary substances.

There are three major nutrients, "carbohydrate," "lipid," and "protein," generate energy, but we focused on energy intake and consumption, and metabolism. This is called "energy metabolism".

Energy metabolism

There are three stages in energy metabolism:

① Basal metabolic rate

Basal metabolic rate is the amount of energy consumed when you are lying down without doing anything.

In other words, it is the minimum energy consumed to sustain life.

• Approximately 1,300-1,600 kcal per day for men in their 20s

• Approximately 1,100-1,200 kcal per day for women in their 20s

The above calorie count is the minimum number of calories required per day for men and women.

Basal metabolic rate has the following characteristics.

• Increases in proportion to the surface area of ​​the body

• Men are higher than women

• Young people are higher than older people

• Higher in cold than in hot

• For the same weight, the one with more muscle mass is higher

② Resting metabolic rate

Resting metabolic rate is the amount of energy consumed when you are resting in a sitting position.

This is the amount of tension energy for maintaining a sitting posture added to the basal metabolic rate, which is about 1.2 times the basal metabolic rate.

③ Metabolism during physical activities

The amount of metabolism during physical activities is the amount of energy for physical activity (exercise / work) added to the amount of metabolism at rest.

Energy requirements

The energy consumed by humans during work and exercise in their daily lives is called "energy requirement".

When considering the amount of energy that a person should consume in a day, the estimated amount of energy that minimizes the risk of excess or deficiency of energy is used as an index.

This estimated amount of energy varies from person to person.

There are three levels of physical activity, "low, normal, and high," such as those who are doing desk work at home, those who are doing heavy labour carrying heavy luggage, those who are not doing anything, and those who are engaged in intense sports. It must be calculated by multiplying the basal metabolic rate.

Estimated energy requirement = daily basal metabolic rate x physical activity level

Estimated energy requirement (kcal / day)

Atwater system

What is the Atwater system?

"Sugars, lipids, and proteins" that serve as energy are called the three major nutrients.

Atwater system exists as a simple method for estimating the energy contained in the three major nutrients.

The amount of energy generated per 1g from each nutrient is "sugar: 4kcal", "fat: 9kcal", and "protein: 4kcal".

These Atwater system can be used to determine the calorific value of food and menus.

Calculation example using Atwater  system

If a certain ingredient contains "sugar: 5g", "fat: 10g", and "protein: 20g", find out how much energy this product has.

Sum each weight (g) x coefficient (kcal / g).

① Sugar: 5 (g) x 4 (kcal / g)

② Lipid: 10 (g) x 9 (kcal / g)

③ Protein : 20 (g) x 4 (kcal / g)

① ＋ ② ＋ ③

= (5 x 4) + (10 x 9) + (20 x 4)

= 20 + 90 + 80 = 190 Answer 190 kcal

English is my second language, so you may find incorrect sentences.

It would be great help if you leave a comment for me. 

Thank you for reading!