super

1. M.Prasad Naidu
MSc Medical Biochemistry, Ph.D,.

2. Introduction
Energy expenditure
2 types
Energy Expenditure in doing D2D activities
EE in doing involuntary works
Calorific value of foods
Bomb calorimeter
Unit of Energy

3. Introduction
Calorific value may be defined as the amount of heat
energy obtained by burning 1gm of the food stuff
completely in the presence of O2
A calorie may be defined as the amount of heat
required to raise the temp of 1gm of water by 10
C
Average values
Car – 4.1; Fats – 9.3; Pro-4.7

4. BMR
The rate of energy production under basal conditions
per unit time (1hr) and per sq.mt of body surface is
known as BMR or
 the amount of heat given out by a subject who
though awake is lying a state of max.physical and
mental rest under comfortable conditions of temp,
pressure & humidity, 12-18hrs after meal (post
absorptive state)

5. Basal conditions
Person should awake but at complete rest both
physical and mental
Person should be without food for atlease 12-18hrs
i.e., post absorptive state
Person should be in recumbent /reclining position on
bed
Person should remain in normal environmental
conditions like normal temp, humidity, pressure etc

6. Determination of BMR
1. Open circuit method: both O2 consumption
and CO2 output are measured
Requires a high degree of tech skill and a
combussom apparatus
Less rapid and more accurate
Tissot method and Douglous method
2. Closed circuit method: only O2 consumption
Clinical practice (2-6 min under basal conditions)
Closed circuit system
Benedict-roth metobolism apparatus

7. Factors affecting BMR
 Age: children much higher than adults
 6y65.5
 12y50.4
 20-30y 40
 40-70y  38.5 to 35
 Sex: women < males (females 5-17y more)
 Surface Area: α BMR ( Cal/Sq.m/hr)
 Climate: colder (high) tropical (low)
 State of Nutrition: BMR malnutrition, starvation↓
 Body Temp: BMR 10% with a rise in 1↑ 0
C
 Barometric pressure: rapid fall of O2 BMR↑
 Habits: Trained athlets & manual workers
 Drugs: Caffine, Benzidrine,epinephrine,alcohol BMR↑
 Anaesthetics BMR↓
 Hormones: thyroid, adrenal medulla, anterior pituitary BMR↑
 ! Mg thyroxine BMR by about 1000 cal↑
 Androgens  10% BMR↑
 Pregnancy: the BMR of pregnant mother after 6 months of gestation rises

8. Clinical aspect
Pathological variations in BMR:
1. Fever:
2. Diseases: (Leukaemias 21-80%), (Polycythemia
10-40%),(Cardiac failure / hypertension 28-80%)
3. Endocrine Diseases
Determination of BMR is mainly used for the
assesment of thyroid function
In Hyperthyroidism +75% or more
In hypothyroidism  -40% or more

9. Importance of BMR
As a diagnostic aid
In the calculation of caloric requirements of an
individual for prescribing a diet of adequate calorific
value and planning nutrition for individuals or
communities and populations at large
To note the effect of foods and drugs on BMR