Good Nutrition

Unit Overview
Nutrition Labels
Graphing
Percents
Formulas
Final Activities
Selected Resources
Credits




Download this unit
(PDF Version)
Student CopyTeacher Copy

Activity 4: Formulas and Equations
(Student Copy)

Materials

  • calculators

Part A

  • In writing formulas, tell what each of your symbols represents.
  • For pertinent items, record variable measures-such as height and weight-that were used to arrive at answers.

1.
  1. Write formulas for females and males for the pounds-per-square-inch method for estimating desirable body weight.

    Females: allow 100 pounds for the first 5 feet, then add 5 pounds for each inch thereafter


    Males: allow 105 pounds for the first 5 feet, then add 6 pounds for each inch thereafter


  2. Estimate your body weight or that of a classmate using the method.


    Does the method seem to give a reasonable estimate of desirable body weight? Why or why not?


Desirable body weight is only an estimate, because it does not account for factors such as body composition (fat versus muscle, the latter weighing more) or body frame size.

2. You might be considered to be overweight if your body weight is 10% or more above your desirable body weight, and you might be considered to be underweight if your body weight is 10% or more below your desirable body weight. A person whose body weight is 20-40% above her/his desirable body weight is considered to be mildly obese, whereas 41-99% above desirable body weight is moderately obese and 100% above is severely (morbidly) obese. Health risks are associated with being either too far above or below your desirable body weight.

  1. Construct a formula for determining the percent difference between actual and desirable body weight.


  2. Use your formula to complete the following chart. The third column shows the estimated then actual percent difference between the actual and desirable body weights (round to the nearest whole percent). Estimate the percent difference before you find the actual difference. The last column tells whether the actual body weight is "normal," (less than 10% from the desirable body weight), underweight, overweight (10-19% above desirable body weight), or one of the classifications of obese.

    Actual
    Body Weight    		 Desirable
    Body Weight    		 Percent Difference
    (estim./actual)    		 Body Weight
    Classification
    177 lb.
    140 lb.
    		 /
    131 lb.
    122 lb.
    		 /
    171 lb.
    195 lb.
    		 /


3. The Recommended Dietary Allowance for protein for adults is 0.8 grams per kilogram (2.2046, or about 2.2, pounds) of desirable body weight.

  1. Write a formula for an adult's daily protein needs in grams.


  2. Using the desirable body weight for you or a classmate (found by using the method shown in #1 or by consulting a height/weight table), use your formula to determine how many grams of protein are recommended for your (or her/his) daily diet.


4. The approximate number of calories you expend by running a certain distance can be found by taking 0.73 times your body weight in pounds times the number of miles run.

  1. Write a formula for calories expended for running a certain distance.


You do not need to tell what each symbol represents in B and C (i.e., give the formula only without explanation).

  1. Write a formula for swimming, which uses about four times as many calories as running.


  2. Write a formula for bicycling, which uses about one-third as many calories as running.


  3. Find the amount of calories that you or a classmate would expend for running, swimming, and bicycling 2.5 miles each (probably not all back-to-back!).
    running:
    swimming:
    bicycling:


5. Harris-Benedict Estimated Basal Energy Expenditure (BEE) tells how many calories you expend or use daily (and, thus, can ingest to maintain weight):

females:
BEE = 655.10 + (9.56 x weight in kg) + (1.85 x height in cm) - (4.68 x age in yrs.)

males:
BEE = 66.47 + (13.75 x weight in kg) + (5.0 x height in cm) - (6.76 x age in yrs.)

Use the above formula to find the base energy expenditure for yourself or for a classmate. Now multiply your answer by a factor from 1.2 to 2.1 to allow for your activity and stress levels, which expend more energy (calories). The lowest number (1.2) represents the lowest level of activity and stress, whereas the highest number (2.1) represents the highest amount of activity and stress (estimate a number for the person for whom you are finding a BEE). Remember to convert your weight from pounds to kilograms (see #1) and your height from inches to centimeters (1 in. = 2.54 cm).


6. A simpler formula--used to estimate basal metabolic rate (BMR)--follows. BMR is the rate at which you use energy (measured in calories expended daily) when completely at rest.

females:
BMR = 21.6 x K, where K is body weight in kilograms

males:
BMR = 24 x K, where K is body weight in kilograms

  1. Find the estimated BMR for yourself or for a classmate. Remember to change your weight from pounds to kilograms. Also, remember that the answer should be listed as calories per day.


  2. Your BMR declines as you grow older, at the rate of about 2% per decade beginning with the 30s.

    • Find the BMR at age 50 for the person listed in A above.


    • Describe how you found your answer.


    • What meaning does the decline of BMR with age have in regard to your body weight?


© Copyright
Area 10 Mathematics and Technology Professional Development Center
Permission is granted to duplicate these materials for classroom use.

Last updated on 1/30/1999
Comments: egalindo@indiana.edu
http://www.indiana.edu/~atmat/units/nutrition/nutr_s4.htm