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Weight for Height

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					Weight for Height
Desirable Body Weight

  Desirable, ideal, optimal
  “What weight should I be?”
  Weight for height
  Weight for height with frame size
  Weight with optimal % body fat
  BMI - Body Mass Index
Weight for Height

   Epidemiologists needed a measure of obesity
   Often questionnaire data on height and weight
    alone
   “Ideal” and “Desirable” Weight tables
   Metropolitan Life Weight for Height Tables
Weight for Height Tables

                                                     WOMEN2
                                Height     Small      Medium    Large
                               ( Inches)   Frame       Frame    Frame
                                 58"       102-111    109-121   118-131
Metropolitan Insurance Co.,      59"       103-113    111-123   120-134
1983, weights at ages 25-59      60"       104-115    113-126   122-137
                                 61"       106-118    115-129   125-140
based on lowest mortality.       62"       108-121    118-132   128-143
                                 63"       111-124    121-135   131-147
Weight in pounds according       64"       114-127    124-138   134-151
                                 65"       117-130    127-141   137-155
to frame (in indoor clothing     66"       120-133    130-144   140-159
weighing 3 lbs., shoes with      67"       123-136    133-147   143-163
                                 68"       126-139    136-150   146-167
1" heels).                       69"       129-142    139-153   149-170
                                 70"       132-145    142-156   152-173
                                 71"       135-148    145-159   155-176
                                 72"       138-151    148-162   158-179
Frame Size
                              Height (cm)   Humerus Width
                                                (cm)
                       Men     155-157.5      6.35-7.30

                               160-167.5      6.67-7.30
Estimate of
                               170-178        7.00-7.62
Skeletal Proportion            180-188        7.00-7.94
                                 190.5        7.30-8.25

                      Women    145-157.5      5.72-6.35

                               160-178        6.03-6.67
                                 180.5        6.35-7.00
Weight for Optimal % Body Fat

   If you know the current % body fat, weight for
    any optimal % body fat can be calculated.
                            Classification        Men       Women
Consensus of an expert      Essential fat         1 – 5%    3 – 8%
panel (1986).
                            Most Athletes        5 – 13%    12 – 22%
Arbitrary cut-off points.   Optimal Health       10 –25%    18 – 30%
                            Optimal Fitness      12 – 18%   16 – 25%

                            Borderline Obesity   22 –27%    30 – 34%
Calculation of optimal weight range

   1. Calculate Fat Weight (FW)
          FW = body weight x Ft
            –   Where Ft = fractional expression of % body fat

   2. Calculate Fat-Free Weight (FFW)
          FFW = Body Weight – FW
   3. Calculate the desired target weight (TW)
          TW = FFW / (1 – Fx)
            –   Where Fx = fractional expression of % body fat
Example Calculation: Young Male
Current weight =100kg, %body fat = 34%

   1. Calculate Fat Weight (FW)
          FW = body weight x Ft
          FW = 100 x .34 = 34kg

   2. Calculate Fat-Free Weight (FFW)
          FFW = Body Weight – FW
          FFW = 100 – 34 = 66kg

   3. Calculate the desired target weight (TW)
          TW = FFW / (1 – Fx)
          @ 12%; TW = 66 / (1 - .12) = 66 / 0.88 = 75kg
          @ 18%; TW = 66 / (1 - .18) = 66 / 0.82 = 80.5kg
Weight range taking into account error in
determination of % body fat

   95% confidence estimates of % body fat
    –   % Fat (1.96 x S.E.E.)
    –   34 (1.96 x 3.7) = 26.7 to 41.3% body fat
   95% confidence estimates of FFW are:
    –   upper limt FFW = 100 – 26.7 = 73.2kg
    –   lower limit FFW = 100 – 41.3 = 58.7kg
   Lower limit for target weight at 12% body fat
           –   TW = 58.7 / (1 - .12) = 58.7 / 0.88 = 71.6kg
   Upper limit for target weight at 18% body fat
    –   TW = 73.2 / (1 - .18) = 73.2 / 0.82 = 83.2kg
Body Mass Index
 (Quetelet Index - 1833)
Adolphe Quetelet (1796-1874)


   After development is complete, the weight of
    individuals of both sexes approximates the
    square of the height
   Quetelet Index
     – Weight / Height2
“Best” Weight for Height Index as an
indicator of obesity


 High  correlation with weight
 Low correlation with height
 Good correlation with “fatness”
  criterion
Human Architecture

Tall people are more linear than short
 people
Tall people tend to have proportionally
 longer limbs
Males tend to have proportionally longer
 limbs than females
Allometry

 Growth of one part in relation to the
  growth of another part
 Isometry - same proportions
  maintained during growth (same
  shape)
Physical Dimensions

 [L]   = Length
 [T]   = Time
 [M]   = Mass
VELOCITY =   DISTANCE / TIME
         =   [L]/[T]
         =   [L]1[T]-1
Geometrical Similarity System

   with increase in size there is no change in shape or body composition
Geometrical Similarity System


Length      = [L]1
Mass        =    [L]3


Time        = [L]1
VELOCITY =   DISTANCE / TIME
         =   [L]1/[L]1
         =   [L]1[L]-1
         =   [L]0
Huxley’s Allometric Curve



     Y=     aXb
Huxley’s Allometric Curve


Log10Y = log10a + blog10X
Curve is linearized by “logging” both sides
“b-value” is used to describe relative growth
Canada Fitness Survey (1981)
(20-29 years old)


            WT/HT     BMI     WT/HT3 WT/HTb
Females b=1.549
Weight       0.967   0.861    0.706    0.918
Height       0.144   -0.127   -0.369   -0.005
S 5 SF       0.805   0.821    0.781    0.821
Kin 303 (96-3)
                 Females - Sum 6 Skinfolds vs BMI

      250

      200

      150
 mm




      100

      50

       0
            15             20              25       30
                                  BMI
Ross et al. 1988
    Correlations of BMI with sums of selected anthropometric
    measures (Canada Fitness Survey 1981)

                 Sum of 5      Sum of corrected      Sum of Bone
                 Skinfolds       Limb Girths          Breadths
    Males          0.67              0.56                0.36

    Females        0.72              0.48                0.42


    Correlations of BMI are “good” with sum of skinfold corrected-
     girths and even bone widths
BMI

 BMI  is not an indicator of body fat in
  individuals it is a measure of weight
  for height
 May be used in conjunction with
  other measures

				
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posted:6/6/2013
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Zhengqin Wu Zhengqin Wu
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