General principles

Human Nutrition 3(3+0)
Lesson 9 : BMR-Methods of Measurements and Factors Affecting BMR

General principles

The general principles of measuring energy metabolism are

  • Measuring the volume of expired air during work for fixed periods of 5 to 10 minutes.
  • Collection of a sample of expired air for the analysis of O2 and CO2contents.
  • Calculation of O2 consumption, CO2 output and R.Q.; and
  • Calculation of the energy output from the R.Q. and O2 consumption.

Factorial method for calculating the daily energy requirement:

  1. The daily calorie requirements of an adult man (65 kgs) for varying degrees physical activity.(sedentary, light work, moderate and heavy work)
  2. To this, 8% extra calories are added to meet the needs of S.D.A. of food.
  3. Total calories are expressed as percentage of basal metabolism.
  4. The extra energy required for work over basal metabolism is termed as activity increment.

Table: Energy expenditure * per day (kcal) for various types of activities (Adult 65kgs. – 25 years)


Sedentary work

Light work

Moderate work

Sleep eight hours

480

480

480

Work six hours

720

1350

2250

Recreation four hours

480

480

480

Walking one hour

225

225

225

Houshold wok and gardening four hours

480

480

480


2385

3015

3915

SDA of food (8%)

190

240

312

Total calorie requirements(k.cal)

2575

3255

4227

*Basal metabolism =1,625 k.cal.

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Last modified: Monday, 6 February 2012, 12:42 PM