Energy Requirements.

Total  daily energy expenditure

1.  RMR  ( Resting Metabolic Rate)  60-75% or Basal Metabolic Rate (BMR)

2.  Thermic effect of exercise            15-30%

3.  Thermic effect of food                  10%

4.  Facultative thermo genesis             10 %

RMR is measurement of the energy expended for maintenance of normal body functions and homeostasis plus a component for activation of the SNS.

BMR is the amount of energy the body expends carrying out activities to sustain life.

Thermic effect of exercise it represents the cost of physical activity above basal levels.

Thermic effect of food “ specific dynamic action” is the result of energy expended to digest, transport, metabolize and store food.

Facultative thermo genesis is the change in energy expenditure induced by changes in ambient temperature, food intake, emotional stress and other factors.

Factors Affecting the metabolic Rate.

1. Body Size.

2. Body Composition  ( %lean body mass and % fat body mass).

3. Male or Female.

4. Thyroid status.  Hyperthyroidism may cause up to 50% increase the BMR.

5. Sleep ( decreases BMR to 10 % )

6. Fever ( every degree of temperature rise above 37 C increases BMR 10% ).

7. Pregnancy.

8. Breast feeding.

9. Smoking  (increases BMR by 10 %)

Energy Measurements.

A Calorie is the amount of heat energy required to raise the temperature of 1ml of water at standard initial temperature by 1 degree C.

1 kilocalorie = 1 Calorie = 1000 calories

One kilocalorie = 4.184 kilojoules

Estimating Basal Metabolism.

1. Body Weight Method.

                       1 kcal/kg/hr

2. Harris –Benedict Equation.

                       Height, Weight, Age, Sex

Male – 66.5 + ( 13.5 * B.W. ) + ( 5.0 * HT.) – ( 6.75 * age )

Female – 655.1 + ( 9.6 * B.W.) + ( 1.8 * HT.) – ( 4.68 * age)

Sample:                Body weight 70 kg.

                              Body Weight Method:  70 kg * 24 = 1680 kcal

If a totally inactive 70 kg man consumes a diet of 1680 kcal, he will maintain his body weight.

          3500 kcal is equivalent to 1 pound of body weight.

If a person’s total expenditure for the day is 2500 kcal and he/she only eats 2000 kcal, there is a negative balance 500 kcal.

 Food Energy.

CHO     4.0 kcal/gm

FAT      9.0 kcal/gm

PROT    4.0 kcal/gm

ALCHOL  7.0 kcal/gm

Sample:    food per serving may have the following breakdown:

8 gm of CHO

6 gm of PROT

5 gm of FAT

(8 gm * 4 ) + ( 6 gm  * 4 ) + ( 5 gm* 9) = 101 kcal