Basal metabolic rate (BMR) is the minimum energy required by the body at rest to sustain vital functions like respiration and circulation. BMR is measured using Benedict's-Roth apparatus and is expressed in calories per square meter of body surface area per hour. Normal BMR values range from 35-38 kcal/m2/hr for adult males and 32-35 kcal/m2/hr for adult females. Several factors can affect a person's BMR, including body surface area, age, gender, climate, starvation, exercise, fever, and hormones. An accurate measurement of BMR is important for calculating energy needs and diagnosing thyroid disorders.

1. BASAL METABOLIC RATE
- JASSIM

2. Definition
Requirement of BMR
Calculation of BMR
Normal values
Factors affecting BMR
Significance of BMR
CONTENTS
01
02
03
04
05
06

3. Introduction
Basal metabolic rate is defined as
the minimum energy required by
a person at complete physical
,mental,digestive rest.

4. Requirement of BMR
BMR is the minimum amount of energy required
to carry out basal vital body functions like
respiration, heart rate, circulation, renal functions,
brain functions, conduction of nerve impulse and
transport across membrane etc.

5. Calculation of BMR
BMR is measure using Benedict's-Roth apparatus
Procedure: The subject breathes in oxygen for 6
minutes. Let the volume be Y liters. Calorific value of
O, is 4.8 Kcal/liter. So, Heat produced in 6 minutes =
4.8 x Y Kcal
Heat produced in a hour = 4.8 Y X 10 Kcal.
BMR=(4.8 X Y X 10 Kcal)/A , where A is surface area in
sqm

6. Normal values
BMR is expressed in Kcal/square meter body surface area/hour
(i.e. Kcal/sq.m/hr).
Adult male= 35-38 Kcal/square meter body surface area/hour.
Adult female =32-35 Kcal/square meter body surface
area/hour.
Children =53 Kcal/square meter body surface area/hour.

7. Factors affecting BMR
1) Surface area: BMR is directly proportional to the body
surface area. Higher the body surface area, higher is the
BMR.
2) Age: BMR is higher in infants and young children as
compared to adults. BMR is at its highest during the first 5
years of age and then gradually decreases.
3) Gender: Males have higher BMR than females.

8. 4) Climate: BMR is higher in cold climates compared to warm
climates
5) Starvation: BMR decreases during starvation.
6) Exercise: BMR increases during exercise.
7) Fever: BMR increases during fever. (10- 12% increase is
noted per degree centigrade rise in body temperature).
8) Hormones: Thyroxine increases BMR. So BMR increases in
hyperthyroidism and decreases in hypothyroidism.

9. Significance of BMR
1) Planning balanced diet:
Determination of BMR is important in calculating
energy requirement by a person and planning a balanced
diet.
2) Diagnosis of thyroid hormone disorders:
In hypothyrodism BMR decreases (up to 40%
decrease). In hyperthyroidism, BMR increases (up to 70%
increase).

10. THANK YOU