1. BODY COMPOSITION
Chapter 6

2. TEST YOUR KNOWLEDGE
Exercise helps reduce the risks associated with overweight and obesity even if it doesn’t result in improvements in body composition. True or False?
TRUE. Regular physical activity provides protection against the health risks off overweight and obesity. It lowers the risk of death for people who are overweight or obese as well as for those at a normal weight

3. TEST YOUR KNOWLEDGE
Which of the following is the most significant risk factor for the most common type of diabetes (type 2 diabetes)?
Smoking
Low-fiber diet
Overweight or obesity
Inactivity
C. All four are risk factors for diabetes, but overweight / obesity is the most significant. It is estimated that 90% of cases of type 2 diabetes could be prevented if people adopted healthy lifestyle behaviors. About 18 million Americans have type 2 diabetes, and more than 6 million of those with diabetes don’t know it.

4. TEST YOUR KNOWLEDGE
In woman, excessive exercise and low energy (calorie) intake can cause which of the following?
unhealthy reduction in body fat levels
Amenorrhea (absent menstruation)
Bone density loss and osteoporosis
Muscle wasting and fatigue
ALL FOUR. Very low levels of body fat, and the behaviors used to achieve them, have serious health consequences for both men and woman.

5. BODY COMPOSITION The relative amounts of fat and fat-free mass
Fat-free mass: all the body’s non-fat tissues:
Bone
Water
Muscle
Connective tissue
Organ tissues
Teeth
Body fat:
Essential fat
Nonessential (storage fat)

6. Essential fat
Lipids incorporated to the nerves, brain, heart, lungs, liver and mammary glands
Crucial for the body functioning
3-5% body weight in man
8 – 12% body weight in woman

7. Nonessential fat Extra fat or fat reserves stored in the body
Exists primarily in fat cells or adipose tissue
Located below the skin and around major organs
The amount of nonessential fat depends on many factors: gender, age, heredity, metabolism, diet and activity level.

8. Overweight and obesity
Muscle tissue is denser and heavier than fat, a fit person can easily weight more than the recommended weight on a height/weight table.
For the same reason, an unfit person may weight less than the table’s recommended weight.
It is important to consider body composition – percent of body fat.
Example:
2 woman  5 ‘5’’ tall weight 130 pounds
One has 15% of body weight as fat
The other has 34% of weight as fat
None of them is overweight by most standards, but the second woman is over-fat

9. Overweight and obesity
Overweight: The total body weight above the recommended range for good health
BMI ≥ 25
Obesity: A serious degree of overweight
BMI ≥ 30

10. Prevalence of overweight and obesity among Americans

11. Excess body fat and wellness
As overweight and obesity increase, so do the problems associated with them
Risk of chronic disease and premature death
Metabolic syndrome  resistance to the effects of insulin, high blood pressure, high blood glucose levels, abnormal blood fat levels and fat deposits in the abdominal region.
Heart disease
Cancer
Hypertension
Impaired immune function
Gall bladder and kidney diseases
Skin problems
Sleep and breathing disorders
Erectile dysfunction
Pregnancy complications
Back pain
Arthritis
Bone and joint disorders.
Diabetes

12. Problems associated with overweight and obesity…
Body fat distribution and health
Excess fat in the abdominal area increases the risk of several diseases
Causes are unknown but it appears that abdominal fat is more easily mobilized and sent into the bloodstream

13. Problems associated with overweight and obesity…
Performance of physical activities
Too much body fat makes physical activity difficult
As a consequence, overfat people don’t exercise
An become less fit. They don’t have muscular strength, endurance and flexibility.

14. Problems associated with overweight and obesity…
Emotional wellness and self-image
Being perceived as fat can cause discrimination from others
Can contribute to psychological problems such as depression, anxiety and low self-esteem.
The ideal body presented by the media is an unrealistic goal

15. Problems associated with very low levels of body fat
Having too little body fat is also dangerous
Fat is essential for the functioning of the body
Too little body fat represents
Less than 8-12% in women
Less than 3- 5% in men
Extreme leanness is linked with reproductive, circulatory and immune system disorders and with premature death.
It might also cause amenorrhea in woman and loss of bone mass.

16. Assessing body mass index, body composition and body fat distribution
Body mass index (BMI)
Measure of body weight that is useful for classifying the health risks of body weight
Based on the concept that weight should be proportional to height
BMI doesn’t distinguish between fat and muscle.
Calculated dividing your body weight (Kg) by the square of your height (m).

17. Calculate your BMI
Divide body weight in pounds by 2.2 to convert it to kilograms
Multiply height in inches by to convert it to meters.
Multiply the result of step 2 by itself to get the square of the height measurement.
Divide the result of step 1 by the result of step 3 to de3termine BMI.

18. Assessing body mass index, body composition and body fat distribution…
National Institute of Health NIH guidelines
Consider body fat distribution and other disease risk factors in addition of BMI
Uses the measure of the waist circumference
Disease Risk Relative to Normal Weight and Waist Circumference
Classification
BMI (Kg/m2)
Obesity Class
Men ≤ 40 in. (102 cm)
Women ≤ 35 in. (88cm)
> 40 in (102 cm)
> 35 in (88 cm)
Underweight
Normal
Overweight
Obesity
Extreme Obesity
< 18,5
18,5 – 29,9
25,0 – 29,9
30, 0 – 34,9
35,0 – 39,9
≥ 40,0 I II
III --
Increased
High
Very High
Extremely high
Very high

19. Assessing body mass index, body composition and body fat distribution…
Percent Body Fat
Underwater weighting
The individual is submerged and weighted under water
The percentages of fat and fat-free weight are calculated from body density
Considers that muscle has a higher density and fat a lower density than water.
Overweight people tends to float and weight less under water
Lean people tend to sink and weight more under water.

20. Percent Body Fat Skinfold Measurements
Involves measuring the thickness of skinfolds at several different sites on the body.
You can sum up the skinfold values as an indirect measure of body fatness.
Measured with a device called caliper

21. Percent body fat The Bob Pod
Small chamber containing computerized sensors
Measures body composition by air displacement rather than water displacement
Determines the percentage of fat by calculating how much air is displaced by the person sitting inside the chamber

22. Percent body fat Bioelectrical Impedance Analysis (BIA)
Works by sending a small electrical current through the body and measuring the body’s resistance to it.
Fat-free tissues, where most water is located, are good conductors of electrical current
Fat is a bad conductor.
The amount of resistance to electrical current is related to the amount of fat-free tissue in the body.

23. Percent body fat Advanced Techniques:
DEXA  Dual-Energy X-Ray Absorptiometry
Measures the tissue absorption of high- and low-energy X-ray beams
TOBEC  Total Body Electrical conductivity
Estimates lean body mass by passing a body through a magnetic field.

24. Assessing body mass index, body composition and body fat distribution…
Waist circumference measurement
Waist to hip ratio calculation
Divide your waist circumference by your hip circumference

25. Setting body composition goals
Establish a goal
Choose a target value for BMI or percent body fat
Make sure your goal is realistic: genetics limits your capacity to change your body composition.
If your body composition is close to the recommended range you might want to set a lifestyle goal rather than a specific percent body fat or BMI goal.
Set a target range for body weight
Don’t stick rigidly to a recommended body weight calculated from any formula, other factors should also be considered