a. increased in starvation
b. it is not influenced by hormonal changes
c. it is not affected by dietary changes
d. decreased by 40 % in starvation
e. it is not affected by energy expenditure
Some important points about basal metabolic rate :
1. the energy expended by an individual during resting post-absorptive state is called Basal Metabolic Rate. It represents the energy required for normal body functions .
2. in starvation it is decreased by 40 % .
3. it is influenced by hormones like thyroid hormones and catecholamines .
4. it is affected by dietary component . eg: diet containing protein increases metabolic rate than same amount of carbohydrate and fat .
5. from 50 % to 70 % of the daily energy expenditure in sedentary individuals is attributable to BMR until very old age .
Factors affecting BMR are :
1. Age : BMR is higher in children than adults. With advancing age BMR gradually falls and in neonate BMR is high .
2. Sex : women have lower BMR than male
3. Surface area : BMR is directly proportional to body surface area .
4. Exercise : increases BMR .
5. Climate : in colder climates BMR is higher than in tropical climates.
6. Nutrition : BMR decreases 20-30 % in malnutrition ,starvation, wasting disease .
7. Body temperature : BMR rises by 14 % for each Celsius degree of elevation .
8. Hormones : circulating levels of hormones secreted by thyroid ,adrenal medulla ,anterior pituitary ( eg: GH ) , male sex hormones increase BMR .
9. Emotional state : sympathetic stimulation .
10. Pregnancy , lactation
11. Race
12. Sleep , drugs , barometric pressure etc .
Download and read this article by American journal of nutrition which discusses about the various factors affecting the BMR on priority basis.
The MCQ above was asked in the PGIMER ( PGI ) chandigarh 2001 december paper .
