DEFINITION: Describes the percentages of fat, bone, muscle, and fluid that make up body weight Factors that affect a person’s body composition: Heredity Diet Exercise Occupation

Two people at the same height and same body weight may look completely different from each other because they have a different body composition.

Healthy Body Fat Percentages MALEFEMALE Adults % 20-25% Adolescents10-20% 15-25% Why are adolescent recommendations different than those of adults? Kids grow and develop at different times Why are boys and girls recommendations different? Boys and girls have different hormones that effect their body composition

This is the most widely used method for assessing percent body fat A Skinfold Caliper is designed for measurement of subcutaneous (beneath the skin) tissue 7 SITE SKINFOLD Chest Triceps Axilla Abdomen Suprailiac Thigh Subscapular 3 SITE SKINFOLD (MEN) Chest Abdomen Thigh 3 SITE SKINFOLD (WOMEN) Tricep Thigh Suprailiac HOW ACCURATE IS IT? ± 3% error

Advantages and Disadvantages Advantages Easy to use once skill has been learned Very personalized and Noninvasive Inexpensive way of estimating percent body fat Disadvantages Training required Mostly concerned with subcutaneous fat May not be an ideal measurement for those who are obese and very lean

Bioelectric Impedance Description By standing barefoot on metal foot plates, an undetectably low voltage electric current is sent up one leg and down the other. Since fat is a very poor conductor of electricity, fat will impede the current more so than lean tissue. By measuring the resistance to the current, the machine estimates the percent body fat.

Advantages vs. Disadvantages Advantages Requires little or no technical knowledge Takes less than a minute Can be easily transported from place to place Personalized Disadvantages Moderate accuracy ( ± 3% ) Tends to overestimate lean people and underestimate obese people

Underwater Weighing A.K.A. Hydrostatic Weighing Description This method uses Archimedes principle describing buoyancy. Because bone and muscle are more dense than water, a person with less fat will weigh more in the water. Conversely, fat floats. Therefore, a large amount of fat mass will make the body lighter in the water.

ADVANTAGES AND DISADVANTAGES Advantages This method is currently considered the "gold standard" in percent body fat measurement Accurate (± 1.5 %)%) Very Personalized Disadvantages Usually requires a lot of equipment and space Time consuming and involved Requires in-depth knowledge to administer the tests and compute the calculations Being submerged under water may produce anxiety

Provides an indication of the appropriateness of a person’s weight relative to height Body mass index is determined by the following formula: weight (kg) / height 2 (m) Example: a student weighing 100 lbs (45.36 kilograms) who is 5 feet (1.52 meters) tall would have a BMI of 19.6.

BMI ADVANTAGES Fast Does not require much skill Procedure is less invasive and may be better accepted in some districts. DISADVANTAGE Least accurate (± 5%- 6%) Body mass index does not estimate body fat Only provides information on the appropriateness of the weight relative to the height

ASSESSMENT OF BODY COMPOSITION Doctor’s Office BMI Personal Trainer Bioelectric Impedance Hydrostatic Weighing Skinfold measurements

Good Body Composition Decrease levels of body fat that cause obesity Decrease risk of coronary heart disease Decrease chances for stroke Decrease chances for diabetes Lower blood pressure Lower Cholesterol levels