1 / 44

Body Composition Chapter 4

Body Composition Chapter 4. Body Composition. The relative proportion of fat and fat-free tissue in the body Body composition is not determined by body weight per se, but what the weight is composed of Most commonly uses the 2-compartment model. Confusing Terminology.

philmeade
Download Presentation

Body Composition Chapter 4

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Body CompositionChapter 4 .

  2. Body Composition • The relative proportion of fat and fat-free tissue in the body • Body composition is not determined by body weight per se, but what the weight is composed of • Most commonly uses the 2-compartment model

  3. Confusing Terminology • Overweight- deviation in body weight from some standard in relation to height • Overfat- body fat greater than some standard (BMI ≥ 25) • Obesity- higher amounts of fat that detrimentally affects health (BMI ≥ 30)

  4. Health Consequences of Obesity • Coronary Heart Disease • Hypertension • Type II Diabetes • Hyperlipidemia • Cancers • Orthopedic problems • Poor self-image

  5. Body Composition Terminology • Fat weight (FW)- total fat amount in pounds • % fat- percentage of total body weight that is fat weight • Fat-free weight (FFW) – total fat-free tissue in pounds • % fat-free- percentage of total body weight that is fat-free tissue

  6. Fat Weight + Fat-Free Weight = Body Weight% Fat + % Fat Free = 100%

  7. Computational Example • Weight = 200 lbs; % fat = 20%; • Fat Weight = 200 x .20 = 40 lbs • Fat-Free Weight = 200 - 40 = 160 lbs

  8. Computing Ideal Weight • Ideal Weight = FFW / Ideal % FFW • Example • Body Wt = 180; %fat = 20%; What is ideal body weight at 10% fat? • FW = 180 lbs x .20 = 36 lbs • FFW = 180 - 36 = 144 lbs • IBW = 144 / .90 = 160 lbs

  9. Components of Fat-Free Weight • Muscle • Bone • Organ Systems

  10. Components of Fat Weight • Essential Fat • most is non-visible • associated with deeper body structures • Non-essential or Storage Fat • Beneath the skin and visible • Adipose tissue fat

  11. Gender Differences In Body Fatness Gender Differences in Body Composition

  12. Gender Differences • Females are proportionately fatter than males (as % of body mass) • Female sex hormones promote fat deposition • Male sex hormones promote muscle growth • Most of the female’s increase in fatness is due to an increase in the essential fat stores • Males and females have similar levels of non-essential fat

  13. Quantification of Body Composition • Height/Weight Ratio • Body Mass Index (BMI), Quetelet Index • Body density or % fat • Waist to Hip Ratio

  14. Height/Weight Ratio • Subjective measure • Assumes an average proportion of weight is fat • May incorporate frame size • Not a very desirable method

  15. Body Mass Index • Weight/Height2 ; kg/meters2 • Extensively used in epidemiology studies • Most commonly used measure to define obesity • Does not measure fatness

  16. Problems With BMI • Weight = 280 lbs • Height = 77 inches • %fat = 30% (obese) • BMI = 33 (obese) • Weight = 280 lbs • Height = 77 inches • %fat = 15% (healthy) • BMI = 33 (obese)

  17. Waist/Hip Ratio • Waist circumference/Hip circumference • Waist- smallest circumference between the umbilicus and xiphoid process • Hip – largest circumference around the buttocks • Implication is that as waist get bigger there is more abdominal storage fat

  18. Density and % Fat • Hydrodensitometry • (Underwater Weighing) • Hydrostatic Weighing • Air Displacement Plethysmography • Anthropometry • Skinfolds • Circumferences & Diameters • Bioelectrical Impedance

  19. Hydrodensitometry (UWW) • Measures body volume using Archimedes' principle • Loss of weight in water is equal to the weight of the volume of water displaced • Density = mass or weight/volume

  20. Advantages of Hydrodensitometry • One of the most accurate methods • Disadvantages of Hydrodensitometry • Very subject dependent • Takes 15 minutes • Requires the ability to submerge subject under water • High skill required of technician

  21. Plethsmyography (Bod Pod) • Body volume is determined by using Boyle’s Law – volume is inversely proportional to pressure. • Bod Pod measures pressure differences. • Density = mass or weight/volume

  22. Advantages of Plethysmography • Good accuracy • Little requirement from subject so good for children and older adults • Takes 5 minutes • Low skill required of technicial • Disadvantages of Plethysmography • Cost of equipment is $30,000

  23. Skinfolds • Based on the principle that subcutaneous fat at various locations (ie. The skinfolds) is predictive of total body fatness • Most equations use at least 2 skinfolds • Generally, the more skinfolds the more accurate the prediction of body fatness

  24. Advantages of Skinfolds • Subject has to do little • Many specific equations are available • Cost effective • Only takes 2-3 minutes • Moderate accuracy • Disadvantages of Skinfolds • High technical skill required

  25. Bioelectric Impedance Analysis (BIA) • Measures the resistance to a small electrical current introduced into the body (Impedance) • Once the impedance is determined then body water is determined. • Principle is that water is a good conductor and fat is a poor conductor of the electrical current. • More resistance = less body water = more fat • Less resistance = more body water = more muscle

  26. Advantages of BIA • Subject has to do little • Only need access to hand and foot • Equipment is relatively inexpensive- $2000 • Moderate accuracy • Disadvantages of BIA • Highly dependent on hydration status

  27. Interpreting % Fat Values • All methods of measuring % fat have a certain amount of inaccuracy! This inaccuracy is determined by the Standard Error of Estimate (SEE). • The SEE tells you the amount of deviation from the true % fat you can expect from a particular method.

  28. There is a 67% probability that the true % fat is within + or - one SEE from the measured value. • Example: Measure % fat = 20%; SEE = 3 % units of body fat There is a 67% probability that the true % fat is between + or - one SEE or 3 % units of fat. or between 17 - 23 %.

  29. There is a 95% probability that the true % fat is within + or - two SEE from the measured value. • Example: Measured %fat = 20% SEE = 3 % There is a 95% probability that the true %fat is within + or - two SEE or 6% of the measured value or 14 - 26 %.

  30. SEE of Common Methods • UWW – 1.5-2.5% • Plethysmography – 2.2-3.7% • Skinfolds – 3-4% • Bioelectric Impedance • Whole Body – 3-4% • Segmental – 4-6%

  31. Healthy Values for %Fat • Reasonable & Healthy %fat Range • Males: 10 - 20% • Females: 15 - 30%

  32. Computing UWW WT in air (kg) BD = Wt in air – WT in H2O - RV (L) +0.1 Density H2O

  33. Converting Density to % FatSiri Equation 495 - 450 %fat = Density

More Related