BMR (Basal Metabolic Rate)

Basal Metabolic Rate (BMR):-

  BMR is the amount of energy per unit of time that a person needs to keep the body functioning at rest.

  BMR is calculated by three different equations:-

(i) Katch McArdle formula:-

BMR Kcal/Day

= 370 + 21.6 x Lean Body Mass ( kg)

LBM= Wt(kg) x ((100-Bodyfat%/100)

Or, 

LBM for Male:-

 0.407x wt (kg) +0.267 x height (cm) -19.2

LBM for Female:-

0.252 x wt (kg) + 0.473 x height (cm)- 48.3

(ii) Miffin St. Jeon equation:-

BMR Kcal/day

= {10 x body wt. (kg)} + { 6.25 x height ( cm) - 5 x age ( yr) + s* Kcal / day

        Where, s*= +5 for male and -161 for female.

(iii) Harris Benedict's Equation(1919):-

It is the oldest method.

For Male:-

BMR Kcal/day

= 66.5 + {13.75 x wt (kg)} + {5.003 x height ( cm)} - {(6.75 x age (yr)}

For Female:-

BMR Kcal/Day

= 655.1 + {9.563 x wt. (kg)} + {1.805 x height ( cm) } -{4.676 x age (yr)}

Determination of daily calorie needs :-

Daily calorie needs depends upon activity factors which is variable:-

(i) Sedentary ( little or no exercise )

     Kcal = BMR x 1.2

(ii) Little exercise/ sports 1-3 days/week

     Kcal = BMR x 1.375

(iii) Moderately active ( moderate exercise/ sports 3-5 days/week):-

     Kcal = BMR x 1.55

(iv) Very active ( hard exercise/ sports 6-7 days /week):-

    Kcal BMR x 1.725

(v) Extremely active ( very hard exercise/ special / physical job):-

   Kcal = BMR x 1.9

Factors of BMR:-

(i) Fat Free Mass ( FFM):-

It is the wt of the body without the wt of fat tissue.

   FFM of male > FFM of female

(ii) Fat Mass:- Much lower FM also has an influence on BMR.

(iii) Age:- During growing period BMR increases with the increase of age .It is due to increase of mussle tissue i.e. FM. The case is opposite in adult age ,since, FM drops.

(iv) Sex:- BMR of male is higher than the BMR of female, because FM is high in male. So, +5 Kcal /day for male and -161 Kcal for female is added in Maffin St Jeon formula.

(v) Exercise:- During exercise BMR increases.

(vi) Temperature:- With the increase of body temperature the BMR of the individual is also increases.

(vii) Temperature of environment:- In cold weather BMR turns high to keep body worm.

(viii) BMR is high in Increase of hormone in blood and Pregnency time . Genetics of individual has also affect on BMR.

Exercise:-

Calculate the BMR of a male aged 60 yrs , height 5'4" and 150 lb wt.

Solition:-

5'4"= 162.56 cm

150 lb= 68.04 kg

So, BMR Kcal/day

= 10 x 68.04 + 6.25 x 162.56 - 5 x 60 + 5

= 680.4 + 1016 - 300 + 5

= 1696.4 - 300+5

= 1696.4 - 295

=1401.4 Kcal/day

Find out the BMR of a 25 yr female of 5'8" and 132 lb wt.

Solution,

5'8" = 172.72 cm

132 lb = 59.87 kg

BMR Kcal 

= 10 x 59.87 + 6.25 x 172.72 - 5x 25 - 161

= 598.7 + 1079.5 -125-161

= 1678.2- 286

= 1392.2 Kcal/day