Weight Versus Body Composition Comparing and Contrasting the Methods for Assessing Body Composition

Statistics: Let’s see how you do. Between 1962 and the year 2000, the number of obese Americans has almost tripled. Answer the following questions with the I-Clickers: 1. What percent (approximate) of Americans are considered overweight? a) 15% c) 60% b) 30% d) 75% 2. What percent (approximate) of Americans are considered obese?

Statistics: Let’s see how you do. 3. Childhood obesity in the U.S. has ____ in the past 20 years. a) stayed the same c) tripled b) doubled d) quadrupled 4. On the average, adult Americans gain ___ pound(s) yearly between the ages of 35 and 50. a) one pound / year c) three pounds / year b) two pounds / year d) five pounds / year

Statistics: Let’s see how you do. 5. According to the U.S. Surgeon General, obesity is responsible for _____ deaths every year. a) 100,000 c) 300,000 b) 200,000 d) 500,000

What is body composition? When we just measure our weight, we are unable to distinguish between pounds that come from fat and pounds that come from muscle. Both numbers together are a better indicator of health and fitness. It is not the amount of weight you have, but the amount of total body fat that is potentially dangerous to your health. Body composition is the proportion of fat and fat-free mass (muscle, bone and water) in the body.

Recommendations for body fat percentages Medical professionals have determined that a healthy range of body fat is: Men = 14% - 20% Women = 17% - 24% Note: For your own body fat range, consult your physician.

Methods for Comparing Body Fat Height-Weight Charts Body Mass Index Waist to Hip Ratio Skin-fold Measurements Hydrostatic Weighing Electrical Impedance Analyzers

Height - Weight Charts In the past, many individuals relied on height-weight charts to determine if his/her weight was at an acceptable level. These charts listed an “acceptable range” (example: 110-135 pounds) based on a person’s gender age height Strengths: easy to use Weaknesses: can be inaccurate for some people because it doesn’t measure body fat

Hydrostatic Weighing In this method, an individual is submerged and weighed under water. The percent of body fat can be calculated from body density. Muscle has a higher density and fat has a lower density than water. Calculations are made to determine the percentage of body fat.

Hydrostatic Weighing Weaknesses: Requires special equipment and facilities, not available everywhere Testing is time-consuming and involved Is sometimes undesirable because it can be difficult and uncomfortable to achieve accurate results Therefore, it is recommended to measure three to five times and average the results for the most accurate body composition analysis (BCA).

Strengths of Underwater Weighing It has long been considered the laboratory “gold standard” because it is fairly accurate, especially if the Body Composition Analysis is measured several times with all the results averaged together.

Skin-fold Measurement The skin-fold measurement technique measures the thickness of fat under the skin. Using hand-held calipers that exert a standard pressure, the skin-fold thickness is measured at various body locations (three to seven test sites are common.) The numbers are put into an equation to predict body density and body fat percentage.

Skin-fold Measurement Strengths: easy to use once skill has been mastered inexpensive doesn’t take much time noninvasive method Weaknesses: range of error (+/- 3% error, when done accurately) competence of technician the calipers have to be accurately calibrated in order to increase accuracy

Example: Weight = 150 lbs, Height 5’5” (65”) Body Mass Index (BMI) BMI is a number calculated from a person’s weight and height. Pounds and Inches Formula: Weight (lb)/[height (in)]^2 x 703 (Calculate BMI by dividing weight in pounds by height in inches squared and multiplying by a conversion factor of 703.) Example: Weight = 150 lbs, Height 5’5” (65”) Calculation: [150/(65)^2] x 703 = 24.96

Interpretation of BMI for Adults The standard weight status categories associated with BMI ranges for adults are shown in the following table: BMI Weight Status Below 18.5 Underweight 18.5-24.9 Normal 25.0-29.9 Overweight 30.0 and above Obese

Advantages and Disadvantages: Body Mass Index does not always accurately predict when weight could lead to health problems because it does not show the difference between fat and muscle. For example, someone with a great deal of muscle may have a BMI in an unhealthy range but still be healthy and have little risk of having a heart attack. The BMI is not accurate for people under 5 feet and in older people who tend to lose muscle mass as they age. It is easy to find a chart or website to calculate your BMI. For most people, BMI is a reliable way to determine if weight is putting health at risk.

Waist to Hip Measurement Waist size is a key indicator of one’s risk of developing obesity-related diseases. If someone carries excess fat around the waist, they are more likely to develop health problems than if they carry fat mainly in the hips and thighs. This is true even if the BMI is within the normal range. Abdominal fat cells appear to produce certain compounds which may influence cholesterol and glucose metabolism.

Waist to Hip Measurement Use a non-stretchable tape measure. Make sure it is level around the body, parallel to the floor and tighten the tape without depressing the skin. Measure the waist at its narrowest point, usually above the belly button. Measure the hips around the widest part of the hip bones. Then divide the waist measurement by the hip measurement.

Waist to Hip Ratio Scoring: Acceptable Unacceptable Excellent Good Average High Extreme male <0.85 0.85-0.90 0.90-0.95 0.95-1.00 >1.00 female <0.75 0.75-0.80 0.80-0.85 >0.90

Waist to Hip Measurement Women with a waist measurement of more than 35 inches or men with a waist measurement of more than 40 inches may have a higher risk of disease and of developing certain health problems such as: type 2 diabetes heart disease, stroke some types of cancer sleep apnea osteoarthritis gallbladder disease liver disease irregular menstrual periods

Waist to Hip Measurement Android or "apple-shaped" obese people are more vulnerable to disease than those who are "pear-shaped."

Strengths and Weaknesses This method does not indicate how much fat or how much muscle a person has so it is not a precise method for determining body composition. However, it is a good way to know whether someone is at increased risk for heart disease and/or diabetes.

Bioelectrical Impedance The individual stands barefoot on metal foot plates and an unfelt, safe, extremely low energy/high frequency electrical signal is sent up one leg and down the other. Since fat is a very poor conductor of electricity, a lot of fat will impede the current more so than lean tissue. By measuring the resistance to the current, the machine estimates the percent body fat.

Bioelectrical Impedance Accuracy depends on the individual doing the following: Not eating or drinking within 4 hours of the test Not exercising within 12 hours of the test Voiding (urinating) prior to the test Avoiding alcohol Not taking diuretics prior to the test, unless instructed by the doctor Weaknesses: Tends to overestimate lean people and underestimate obese people Accuracy is dependent on variable listed above

Bioelectrical Impedance Strengths / Advantages: Requires only an electrical outlet and the machine Unit can easily be transported Testing takes less than a minute Requires little or no technical knowledge of the operator Cost of administration: free - $30

Why is maintaining a healthy important? Look at the leading causes of death in the U.S. For which of these causes of deaths does a person’s chances increase if they become overweight? Are there other risk factors associated with weight that would increase a person’s chances of developing these conditions?