Name ____________________
Body Composition Lab
Regents Biology
Background information:
When people consider their body composition, they commonly concern
themselves with their body weight as measured by the bathroom scale and whether or not
their total weight in pounds is greater than available reference norms. Instead, they
should focus on the components of the body that combine to make up total body weight.
Total body weight is comprised of two main components -lean mass; which includes
muscle, bone, connective tissue, & blood; & the second component-fat.
Lean tissue is composed of water, protein, and minerals. Body fat consists of
essential and storage fat. Essential fat is stored in bone marrow, body organs, and the
nervous system. It is required for normal physiological functioning, & in females, serves
to produce female sex hormones. Storage fat is a nutritional reserve found in spaces
between muscles and under the skin. .
All body fat consists of millions of tiny fat cells, each a spherical sac, filled with
droplets of oil known as triglycerides. When triglycerides are not used as an energy
source they are stored in the adipose areas of the body. Adipose cells are notorious for
filling or swelling with fat when it is available in excess. As a result, fat cells increase in
size. There are three periods in your life when the numbers of fat cells naturally increase.
1. Third trimester of prenatal life (7-9 months).
2. First year of life.
3. Adolescent growth spurts.
Body fat percentage refers to the percentage of body fat mass in regards to body
weight. The weight that is not fat is referred to as the lean body mass (fat free body
mass). The human body is made up mainly of water with fat being the next largest
percentage. The remainder of the body consists of carbohydrates and proteins in the
muscles and minerals stored in the bones. Genetics or overeating can predispose an adult
to being over-fat.
The average body fat percentage for a woman is 18-25% and for a man is 1220%.Obesity is defined as the percent of body fat that increases the risk of disease.
Females who become excessively lean, such as long distance runners, gymnasts, skaters,
and ballerinas often experience menstrual dysfunction when their body fat range drops
below the 12-17% range. It seems that women gain fat more easily versus men and have
a harder time losing it. This is a result of the female hormones keeping fat high and
muscle mass low. This lower percentage of muscle mass means women burn fewer
calories than men at rest. Testosterone, the male sex hormone helps build muscle mass
thus males have a higher percent of muscle, burn more calories at rest & have a lower
body fat percentage. Before puberty, males and females have approximately 15% body
fat. After puberty, girls may have 18% body fat while boys may drop to 10% body fat.
Purpose:
In this lab you will learn the information needed to assess your body composition. You
will calculate parts of your body composition and then use an analyzer to determine your
body composition. Finally, you will discuss ways that people can alter their body
composition.
Procedure:
Somatotype
1. Everyone is born with a certain body type or somatotype in which genetics plays a
major role. An endomorph has a body type that is rounded and soft and has a
tendency to carry a higher percentage of body fat. A mesomorph has a square
body with broad shoulders, hard, rugged, prominent muscles and larger
bones -an athletic build. An ecotomorph refers to a thin, fragile, delicate,
linear body type - a runway model build. You may, of course, be a combination
of these.
Which somatotype do you have? _________________________
Frame Size
2. To determine your frame size, measure your wrist in inches with a tape measure
and compare it to the chart below.
Frame Size
Wrist measurement
Height = 5’2” or
under
Wrist measurement
Height = 5’3” to
5’4”
Wrist measurement
Height = 5’5” & up
Small
Medium
Large
5.5” or less
5.56” to 5.75”
5.76” & up
6” or less
6.01” to 6.25”
6.26” & up
6.25” or less
6.26” to 6.5”
6.56” & up
Wrist Measurement _______________
Frame Size __________________
Height/W eight Chart
3. Using your determined frame size, find your height in the appropriate column of
the table below & record the estimated weight range that is provided.
Height ______ Frame Size: _______________ Estimated weight range_______________
Men
Women
Height Small Medium Large
frame frame
frame
128-134
131-141
138-150
5’2”
130-136
133-143
140-153
5’3”
132-138
135-145
142-156
5’4”
134-140
137-148
144-160
5’5”
136-142
139-151
146-164
5’6”
138-145
142-154
149-168
5’7”
140-148
145-157
152-172
5’8”
142-151
148-160
155-176
5’9”
158-180
5’10” 144-154 151-163
161-184
5’11” 146-157 154-166
149-160
157-170
164-188
6’0”
152-164
160-174
168-192
6’1”
172-197
6’2” 155- 168 164-178
158-172
167-182
176- 202
6’3”
162-176
171-187
181-207
6’4”
Weight in shoes with 5 pounds of
clothing
Heig Small Medium Large
ht
frame frame
frame
4’10” 102-111 109-121 118-131
4’11” 103-113 111-123 120-134
5’ 0” 104-115 113-126 122-137
5’1” 106-118 115-129 125-140
5’2” 108-121 118-132 128-143
5’3” 111-124 121-135 131-147
5’4” 114-127 124-138 134-151
5’5” 117-130 127-141 137-155
5’6” 120-133 130-144 140-159
5’7” 123-136 133-147 143-163
5’8” 126-139 136-150 146-167
5’9” 129-142 139-153 149-170
5’10” 132-145 142-156 152-173
5’11” 135-148 145-159 155-176
6’0” 138-151 148-162 158-179
Weight in shoes with 3 pounds of
clothing
Measuring Body Fat
There are many methods to measure and monitor the percentage of body weight that is
fat. You will learn only a few of these.
Waist to Hip Ratio
4. Using a tape measure, find the size of your waist & hips & record the
measurements below. Waist should be measured level with your belly button
while the hip measurement should be taken at the top of your hip bone.
Waist size: _______________
Hip size: _______________
Divide your waist size by your hip size to determine your waist to hip ratio:
Waist/Hips: _______________
If your ratio is greater than or equal to 0.95 for a male or .86 for a female, you have
an apple shape & are at an increased risk for heart disease.
Check one:
Are you at high risk? ____________
or
low risk? ______________
Bioelectrical Impedence
5. This method measures the resistance to a mild electric current that is passed
through the body. Electric currents pass easily through hydrated fat-free tissue
(lean body mass) as compared to fat tissue. Because bioelectrical impedence
measures the body’s water resistance to an electrical current, it is affected by
hydration level, food intake, exercise, skin temperature, and menstrual stage.
Use the Body Fat Analyzer to determine your body fat % & your BMI. BMI will
be discussed in the next section.
To enter data into the analyzer:
1. Press ON/OFF to turn machine on.
2. Press SET to enter as a guest.
3. Press UP or DOWN to change the setting to NORMal. Then press SET.
4. Use the UP or DOWN buttons to adjust your height. Then press SET.
5. Press the UP or DOWN buttons to adjust your weight. Then press SET.
6. Press the DOWN key to enter your age. Then press SET.
7. If you are male press SET again. If you are female, press the UP or DOWN key
until the machine displays female, then press SET.
8. The machine will read READY. To begin to take a reading, stand with your arms
out straight and press the START key. If the machine is working a bar will flash
across the bottom.
9. Record the numbers displayed on the machine in the spaces below. The top
number on the machine is body fat percentage. The bottom number is BMI.
% body fat __________
Body Mass Index
BMI __________
6. The body fat analyzer uses the formula below to calculate your Body Mass Index
(BMI).
(Weight X 703)/ (Height in inches squared)
Body Mass index uses height & weight to estimate a person’s health status with
regards to weight but is extremely inaccurate for individuals who have high muscle
mass since it does not distinguish between fat weight & lean weight.
BMI
< 18.5
18.6- 24.9
25.0- 29.9
30.0 +
Interpretation
Underweight
Normal
Overweight
Obese
According to the National Institutes of Health (1998), 97 million (55%) of people in
the United States have a BMI of 25 or more.
Calculating Desirable Weight
7. Once you have determined your fat percentage, you can make a judgment as to
whether your value is optimal. If you desire to be a different weight, you can use
the following equations to target a percentage of body fat that is healthy based on
your lean body mass. For sake of this exercise, determine a different percent body
fat than your own (desired or not) and calculate a desired weight. The healthy
range of body fat for males is 6-18% while for females a healthy range is
between 18-25%.
SHOW YOUR WORK IN THE SPACE BELOW THE EQUATION:
1. To determine your fat mass weight (the amount of pounds that is fat alone):
a. Divide your body fat percentage by 100.
b. Multiply your answer from a. by your total weight in pounds (as read on
the scale).
Fat mass weight = ____________
2. To determine your lean body weight (the amount of muscle, bone, etc. on your
body):
Subtract your fat mass weight (your answer to #1 above) from your total weight in
pounds (as read on the scale).
Lean body weight= ____________
3. To determine your desired weight (a healthy weight based on your muscle mass &
frame size):
a. Select a healthy body fat percentage for your sex. For sake of this exercise
use a number different than your actual body fat percentage even if it is
not desired. Remember healthy male %= 6-18% & females= 18-25%.
b. Divide your selected body fat percentage by 100. Answer = __________
c. Subtract the answer from b. from 1. Answer = __________
d. Divide you lean body weight from number 2 above by your answer from
c. The result is your desired weight to obtain that body fat percentage
without losing muscle.
Desired body weight = ____________ pounds
Counting Calories
8. To maintain weight a person requires approximately 15 calories per day for every
pound.
a. Calculate the number of calories needed to maintain your current weight
by multiplying your current weight by 15.
Calories needed per day to maintain current weight = ____________
b. Calculate the number of calories needed per day to reach your desired
weight from exercise 7 on the previous page by multiplying your desired
weight by 15.
Calories needed per day to reach desired weight = ____________
For many individuals achieving a few pounds of weight loss can be achieved by cutting
relatively few calories per day. For example, by choosing not to eat one extra bowl of
cereal with milk per day (or choosing to exercise moderately for 30 minutes), an
individual can cut approximately 300 calories from their diet. One pound of body weight
is the equivalent of 3,500 calories thus by cutting only 300 calories per day, an individual
can lose one pound in approximately 12 days.
Questions:
1. According to the height and weight chart and based on your frame size, list the weight
that is appropriate for you. _________________. Are you at this weight now or is it goal
that you would like to reach?
2. If someone's hip-to-waist ratio fell within the high risk for disease category, what steps
could they take to assure good personal health in the future?
3. Why is it better to know your body fat percentage than your weight alone?
4. Edna Eatalot weighs 525 pounds. How many calories does Edna require per day to
maintain her current weight? _______________
5. Billy Bob has a height of 5'4" and a wrist size of 6". What is his frame
size?_______________
6. JoJo Jellybean weighs 165 pounds and measures 20% body fat. How many pounds of
fat does JoJo have on her body? _______________. (Refer back to #1 in exercise 7 for
assistance.)
7. Jim Gymansium adds exercise to his daily routine & burns 200 calories per day. He
also decides to cut out a few snacks from his daily diet & replace them with healthier
alternatives. This cuts an additional 500 calories per day. How many days will it take Jim
to lose 2 pounds? ____________________ (Remember 1 pound = 3,500 calories.)