BMR.ppt

biochem

2. DIET & NUTRITION
• Caloric valueis defined as the amount of heat energy obtained by burning 1 gm
of food stuff completely in the presence of O
2.
• In vitro caloric valueof different foodstuffs is determined in a special apparatus
called BOMB CALORIMETER.
PROCEDURE & PRINCIPLE: -
1. A weighed amount of the sample is burnt in an atmosphere of O2 by an
electrically heated platinum wire.
2. The heat evolved is absorbed in a weighed amount of water which surrounds the
burning chamber.
3. Rise of temperature is recorded with the help of sensitive thermometer.
• Unit of energy:-The unit of energy is calorie (c) .
• What is CALORIE ? is defined as amount of heat required to raise the
temperature of 1 gm of water by 1C
◦
( specifically from 15 C
◦
to 16 C)
• KILOCALORIE:-is a unit thousand times of the ordinary calorie. Kilocalorie
ic Calorie with capital C.Calorie usually means kilocalorie.
• AVERAGE ENERGY VALUE
• Carbohydrates:-4.1
• Fats:-9.3
• Proteins:-4.1

3. • Metabolicrate:-outputofenergybyapersonwhichisexpressed
askcals/sqmeterbodysurfacearea/hr.
• Basalmetabolicrate(BMR):-Definedastheamountofheatgivenoutbya
subjectunderbasalconditionandisexpressedaskcals/squaremetersurfacearea
ofthebody/hourunderbasalconditions.
• TheBasalconditions
1.Person should be awake, at complete rest both physical & mental.
2.Person should be in overnight fast (post absorptive state)
3.Should be in recumbent /reclining position in bed
4.There should be normal environment, normal temperature & pressure
Normal BMR values
• Adult males =40C/sqm/hr
• Adult female =37C/sqm/hr
Factor influencing BMR
 Age, sex & climate
 Surface area
 Racial variation
 State of nutrition
 Body temperature
 Barometric pressure
 Habits & drugs
 Various hormones
 Pregnancy
BMR calculation by Harris method
BMR (Men)=66+(13.7×W)+(5×H)-=6.8×A
BMR (women)=55+(9.5xW)+(1.8xH)-(4.7xA)
BMR by Read’s formula:-
BMR=0.75 (PR+ 0.74x PP) -72

4. BMR / BEE
BMR calculation requires : surface area , RQ & O2 consumption / L
1. Du Bois’surface area formula:
A=H0.725×W0.425×71.84
Where,
A= Surface area in sq.cm
H= Height in cm
W= Weight in Kg.
A (in sq. meter)= H0725×W0.25×0.007184
2.Surface area is also calculated by using Nomogram.
• A BMR between -15 to +20% is considered normal.
Present deviation of BMr
difference between actual & standard BMR
=___________________________________ x 100
standard BMR for particular age & sex

5. Increased BMR
Fever : infections and febrile diseases
Thyrotoxicosis
Leukaemias & polysythemia
Hyperthyroidism & cushing diseases
Decreased BMR
Myxoedema
Addison disease
During sleep
Importance of BMR
1.As a diagnostic aid
2.For calculation of caloric requirements
3.To find out Effect of food and drugs.

6. Respiratory Quotient (RQ)
• RQ is the ratio of the volume of CO2 produced by the
volume of O2 consumed(CO2/O2),during a given time.
• A Normal RQ in a healthy adult over mixed diet =0.85
• FACTORS AFFECTIN RQ: -
1.nature of diet
CHO=RQ 1
Fats= RQ 0.7
proteins=RQ 0.8
2.Interconversions in body
3.Muscular exercise
4.Starvation
RQ isincreasedin acidosis, febrile conditions.
RQ is decreasedin alkalosis, advanced D.M.
IMPORTANCE OF RQ
1. a guide as to the type of food burning
2. helpful in determining metabolic rate
3. helps in diagnosis of various diseases
CALORIC REQUIREMENT depends upon
1.BMR
2.Specific dynamic action (SDA)
3.Physical activity
Kcals/LO2 at RQ values.
Kcal/L
O2
RQ
4.6890.71
4.7390.75
4.8010.80
4.8250.82
4.8620.85
5.0471.00

7. Energy expenditure/hr of 70 Kg person
84 kcalsLying still and awake
100 kcalsSitting at rest
120 kcalsStanding still
192 kcalsWalking slowly (I mile/hour)
348 kcalsWalking moderately fast (4 miles/hour)
500 kcalsSwimming
650 kcalsWalking very fast
1100 kcalsWalking upstairs

8. Total calorie requirements/24 hrs
MEN: Calories
Shoe maker (sedentary) 2000-2400
Carpenter (light work) 2700-3200
Farmer(moderate work) 3200-4000
Labourer (heavy work) 4000 or more
WOMEN:
House wife 2300-2900
Seamstress( needle) 1800-2100
Seamstress (machine) 2300-2900
Infants up to 6 months 110-120
Infants up to 1 yr. 115-150
Children 1-10 yrs. 115-2000
Boys 10-18 yrs. 2500-3000
Girls 10-18 yrs. 2250-2300

9. Standard BMR values (kcals/sq.meter/hr)
BMR
Male Female
Age
(years)
53.0 53.001
49.3 48.405
44.0 42.510
38.6 35.320
36.3 34.940
34.9 32.760

10. SOME TERMINOLOGIES
•Resting Metabolic Energy (RME)
It is energy expenditure measured in individuals at rest without food for 2 hrs.
It is 10 % greater than BMR.
•Minimum Metabolic Rate
It is minimum metabolic rate during sleep / starvation.
•Maximum Metabolic Rate
It is metabolic rate during the severest possible muscular exercise/athletes.
•Dietary Reference Intake (DRI)
The DRI consists of four dietary reference standards for the intake of
nutrients designated for specific age group, sex & physiologic states.
1.Estimated average requirement (EAR)
2.Recommended dietary allowance (RDA)
3.Adequate intake (AI)
4.Tolerable upper intake level (UL)
•Body Mass Index (BMI)
BMI (kg/m2) is the ratio of (wt in kg) ÷(height in meters)
2

11. Energy calculations
1. Apersonutilized60LO2inonehourwhilehewaswalking.HisRQwas0.85.findouthisenergy
expenditurein24hourswhilehewaswalking(atRQ0.85,1literofO2liberates4.862kcals).
2. InatestforBMR,awomanaged40yrs,64inchtallandweighing125poundsconsumes1200ml
O2atSTPin6mins.FindoutherBMR.(RQ0.82,O2Liberated4.825kcals).
3. Anadultmanof70kgbodywt&surfacearea1.7sq.meter,basalrequirements40C/sqmeter/hr.
calculateCal/24hr.
4. Ayoungmedicalstudentaged21yrs.havingwt.52kgandBMR39,dailytakescarbohydrates
210g,proteins55gandfats65g.Howmanykcals.doesheconsumeeachday.
5. Auniversitystudentaged32yrs,height170cmandwt68kg,consumedanaverageof1.2LofO2
atnormaltemperature&pressurein6minperiod.CalculatehisBMR&%BMRdeviation.(1
LiterO2consumed=4.825C,surfacearea=1.8sq.meter).
6. Apersonconsumes250mlO2and200mlCO2in1min.Calculategasvolumesin24hrs.Also
findoutRQ.
ImportantVivaQuestions:
 DefineBMR&namefactorseffectingBMR.
 Enumerateconditionincreasing/decreasingBMR.
 ExplainRQandfactorsinfluencingRQ.
 Explainspecificdynamicactionoffood.