1. Body Composition Assessment
A description of assessment methods.

2. Body Composition
The relative % of body weight that is fat and fat-free tissue

3. Why measure body comp? Health Implications Make BW recommendations
there is an ideal % fat for health reasons (prevent onset of diabetes, CHD, BP, etc…)
Make BW recommendations
can use % fat values to determine an ideal BW
how much fat to lose versus how much muscle to gain

4. Height - Weight Tables
Body composition is a better indicator of fitness than body weight/height. Standard height-weight tables do not provide accurate estimates of what you should weigh because they do not take into account the composition of the weight. A subject can be overweight according to these tables yet have very little body fat.

5. For example: Body Builder: 5’5” 200 pounds
overweight according to height/weight tables
4% body fat
ALL MUSCLE!!!

6. Fat Mass vs. Fat-free Mass
Two Component Model
Fat-free mass is composed of all of the body's nonfat tissue including bone, muscle, organs, and connective tissue. Fat mass includes all the body’s fat along with essential fat.

7. Essential Fat All fat is not bad!!
We need fat for padding of organs, insulation, energy source
There is a minimum amount that we need to function daily = essential fat
Gender specific
males ~ 3%
females ~ 7%

8. Essential Fat Why the differences?
A male at 7% is like a female at 17%
Women are more complicated!!
Women have babies, menstrual cycles, etc… and need more fat for the survival of the species

9. Methods 1. Under Water Weighing (Hydrodensitometry)
2. Bioelectrical Impedance (BIA)
3. Dual-Energy X-ray Absorptiometry (DEXA)
4. Near-Infrared Interactance (NIR)

10. Methods
Anthropometric Measures (anthro=body; metric=measuresbody measurements)
5. Skinfolds
6. Circumference (WHR)
7. Diameters (body typing)
8. Height (BMI)
9. Others…..??

11. Hydrodensitometry
Used to be considered the most accurate (up for debate now that DEXA is used)
+2.5% if done with experienced subjects

12. UWW Fat Component - Fat (adipose)+Neural+Essential Fat
density of 0.9 g/ml
Fat-Free Component - muscle+bones+ tendons+organs
density of 1.10 g/ml

13. UWW
Water Density ~ 1.0 g/ml (temperature of the water affects the density)
Thus, if more fat  will float (fat is less dense than water)
If more muscle  will sink (muscle is more dense than water)

14. Procedures 1. Wear light clothing (swimsuit)
2. Use bathroom prior to weighing
3. Calibrate scale
4. Weight the chair or seat and equipment
5. Measure water temp
6. Remove all air from clothing

15. Procedures 7. Sit in seat 8. Submerge
9. Blow all air out of lungs and remain still
trials; average of the highest three
11. Subtract weight of apparatus from average UWW

16. Equations
% fat = 457÷BD
%fat = 495÷BD - 450

17. Sources of Error Not getting all air out Reading scale wrong
Are not using the correct equation
Estimation of RV

18. BIA
Based on the premise that fat-free tissue is a better conductor of an electrical current (contains water and electrolytes) than fat tissue
The resistance to current flow is inversely related to FFM

19. BIA Abstain from eating or drinking for 4 hours prior
No exercise 12 hours prior
No alcohol 48 hours prior
No diuretics (caffeine) prior to assessment

20. Advantages Non-invasive Safe Easy to administer
Accurate on some populations
Field technique

21. Disadvantage The accuracy has been questioned:
Skinfolds 2.4 % error
BIA 5% error
Visual 3.1% error
Race cannot be entered into the machine
Children distribute water differently than adults

22. NIR
Based on the premise that the degree of infrared light absorption is related to the composition of the substance through which light passes
Fat and Fat-Free Mass absorb and reflect light differently

23. Advantages
Non-invasive
Safe
Easy to administer
Field technique

24. Disadvantages Cost? Is it worth it? Few Age/Gender Specific Equations
Accurate?
Futrex %
Futrex 5000A 6.3%
Futrex %
Sum
BIA %

25. Skinfolds
Measurement of subcutaneous adipose tissue at specific anatomical sites
BD or %fat is obtained with the use of equations (either population specific or generalized)

26. SF Procedures Take all measurements on the right side of the body
Identify and mark site
Grasp skin and fat between thumb and index finger 1cm above marked site
Continue grasping at the site while taking the measurement

27. SF Procedures
Take at least 2-3 non-consecutive measurements - if values vary by +2mm take additional measurements
No measurements directly after exercise

28. Sites Chest Subscapular Midaxillary Suprailiac Abdominal Triceps
Biceps
Thigh
Calf

29. Equations Jackson’s 3-site
Males - BD= (sum3) (sum3) (age)
chest, abdomen, thigh
Females - BD= (sum3) (sum3) (age)
triceps, suprailiac, thigh

30. Skinfolds
Use text table 4.1, 4.2, 4.3, 4.9

31. Circumferences
1. Waist to Hip Ratio
2. Determination of Body Comp

32. Waist to Hip Ratio Indication of the pattern of body fat distribution
Indicator of the health risks of obesity
excess trunk fat - increased risk of hypertension, type 2 diabetes, high cholesterol, CAD, premature death

33. Measurements Made with a tape measure
Waist - at the level of the umbilicus
Hips - biggest part of the gluteals

34. Waist to Hip Ratio Risks increase with increasing ratios Men
Very low risk <.95
Low risk
High risk >1.00

35. Waist to Hip Ratio Risks increase with increasing ratios Women
Very low risk <.80
Low risk
High risk >.85

36. Determination of Body Comp
Figure 4.5 and Table 4.4, 4.9

37. Body Mass Index (BMI)
Ratio of a person’s weight (kg) to the height squared (m2)
Used to categorize people with respect to their degree of obesity
Not used to determine % fat
Table 4.7 and Table 4.8

38. BMI <20 - underweight 20-25 kg/m2 - acceptable
kg/m2 - overweight
> obesity

39. Calculations for Optimal BW
1. Determine % fat
2. Calculate Fat Weight
BW * %fat ÷ 100
3. Calculate Fat-Free Weight
BW - FW
4. Calculate Desirable Weight
FFW ÷ (1- (desired %fat ÷ 100))

40. Calculations 5. Calculate amount of weight that needs to be lost
BW - Desirable Weight
6. Calculate kcal deficit
3500 kcal per pound of weight needed to be lost
7. Assuming loss of 1 pound (3500 kcals) per week, calculate # weeks to reach goal

41. Assignment
Lab 4B