Understand the different techniques used to assess body composition and what it means to be Overweight or Obese
There are multiple ways to measure what a person's body is made of. Some methods are better than others. One distinction everyone must understand when viewing these techniques below is that not all of them will measure Percent Body Fat. Some just give you a status of your health.
BMI
For instance, the simplest form of measuring how healthy your body is can be completed using your Bod Mass Index (BMI) ("Glossary"). BMI is calculated by taking the your weight (in kilograms) and dividing it by the square of your height (meters2).
For more information, please go to this page. It includes a table of health categories based on BMI values: https://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/index.html
Online tools are readily available for you to do this... Click Here for BMI calculator
However, the BMI is overly simplistic and could be missing many people who could be obese...
Click Here for a news report that questions the use of BMI
Body Fat Distribution
Other techniques that do not look at the total amount of fat you have on your body, but where that fat is located, is either the waist circumference or waist-to-height ratio.
Both of these will look at how much fat is in/around your belly in Adipose Tissue ("Glossary") because the amount of fat on your abdomen is related to your level of risk for multiple diseases... Click Here for article on Abdominal Fat and Disease
The following video describes the waist circumference measurement up to the :43 second mark, then talks about the Waist-to-Hip (not height ratio). But researchers having been shying away from Waist-to-Hip because it can give a false positive indicator of disease for thin people...
Click Here for Waist Circumference video
The Waist-to-Height ratio can be calculated here... Click Here for waist-to-height ratio calculator. Research has been showing how it is an improvement over normal weight-based measures for testing for diseases... Click Here for waist to height ratio research article
Percent Body Fat
There are Three "Gold Standard" measures of Body Composition:
1) Hydrostatic Weighing (also called underwater weighing)
2) DEXA scan
3) Cadaver studies
The most accurate Direct Method is a Cadaver study (yes that means dead people)... but since we want this measurement on a live person, we'll just skip over this one.
The most accurate Direct Method (on a live human being) is a DEXA scan. But this technique can cost hundreds of dollars to perform (so it is not too practical).
Everything else used to measure Body Composition is considered an "Indirect" method (because you are not looking directly at the amount of fat in a dead person or with a computer scanner).
Hydrostatic Weighing (Underwater)
The most accurate method we have to date for an Indirect measure of body composition is underwater weighing (Click Here to watch how underwater weighing is completed). Every other technique found below this one that measures percent body fat is based off of this technique. But the measurements below are much easier to do, especially in a classroom setting.
Skinfold Analysis
The pinching of skinfolds. This is the technique that you can choose to do (or not to do) in our class when we test body composition. Here is a video that shows where the "pinches" will happen when you do this technique... Click Here for video on Male skinfold test and Click Here for video on 3 site skinfold test for females (If you perform this test in class, you will not be asked to get into small shorts/sports bra). Though this technique is not as accurate as underwater weighing, it is still very good and can be used over time to track progress.
Infrared Analysis
One measure that many gyms will use is Infrared analysis...
However, it is not the most accurate nor the most reliable... Click Here for Infrared analysis information
Bioelectrial Impediance Analysis (BIA)
A second measure that is not the greatest is BIA. It can be accurate when done in a controlled setting (like a research laboratory). But at home, there are multiple factors that can through the measurement off... Click Here for BIA information
NORMATIVE CHARTS
For your assignment in this section, you need to look at "Norms" for BMI and Percent Body Fat (if you do the skinfold test).
BMI chart: https://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/index.html (the chart is found under the heading of "How is BMI interpreted for Adults")
Percent Body Fat charts: http://www.bmi-calculator.net/body-fat-calculator/body-fat-chart.php
One last point...
We keep discussing having too much fat. But there is another side to that coin, having too little fat on the body. Having too little fat on the body has its own consequences...
Click this link for Low body fat health issues
And for women, having low body weight, or low calorie intake from excessive dieting, or excessive exercising can lead to Amenorrhea: https://www.mayoclinic.org/diseases-conditions/amenorrhea/symptoms-causes/syc-20369299