A F T E R
the bell
Calories, energy, and the food you eat
There is a great deal of discussion in the United
FIGURE 1
States today about obesity. In any local newspaper you will find articles on the failure of schools
to provide nutritious foods, the war against
obesity and related diseases, and eating foods
that improve and support health. Recently, the
problem of obesity has increased to epidemic
proportions. The best way to battle this epidemic
is through education.
In today’s world of numerous diets and super-sized portions, finding the correct answers
to our nutritional questions can be difficult.
However, there is one basic physical science
rule that holds true: If the caloric intake is
greater than the energy the body needs, the
excess calories will be stored as fat for future
use; conversely, if the calories consumed are
less than the body needs, the energy deficit
will cause the body to burn fat or muscle
tissue. Although generalizations regarding
calorie consumption can be made, assessing
individual caloric needs and utilization is
more difficult. The calories an individual
needs can be affected by metabolism, muscle mass, level
of physical activity, and amount of sleep.
Part of the solution in controlling obesity is to make students aware of the amount and type of food they eat. Once
students recognize this fact, the next step is to have them
read food labels and understand the meaning of the terms
associated with the food. A large part of this understanding
has a great deal to do with how much students know science
content. For example, we often hear how cholesterol negatively affects the body. With a greater scientific background,
students can learn that high-density lipoprotein (HDL), or
good cholesterol, is very important for the body and improves
one’s health because it lessens the amount of low-density
lipoprotein (LDL), or bad cholesterol, in the bloodstream.
LDL, on the other hand, brings cholesterol into the body,
and therefore can negatively impact one’s health.
Students should become familiar with the food and
nutrition pyramid (Figure 1). The U.S. Department of
Stephen J. Farenga ([email protected]) is an associate professor of science education and Daniel Ness ([email protected]) is
an associate professor of mathematics education at Dowling College
in Oakdale, New York.
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The new USDA food pyramid
Agriculture (USDA) recently changed the appearance
of the food pyramid to emphasize that all the food groups
are necessary; the important considerations are how much
food in each group is consumed, and the type of food
within each group that is consumed.
A good activity is to have students calculate the average
amount of energy that a body consumes per hour. Students
should be aware that energy is measured in calories.
Resources
USDA food pyramid: www.mypyramid.gov.
This website identifies the food groups without creating a
hierarchy of some foods being more important than others.
Instead, the USDA shows that all food groups are important.
Whole foods are generally preferred and considered healthier
than processed foods.
Nutrition fundamentals: Calories: http://sportmed.usfencing.org/docs/
Nutrition/Calories.pdf
This document, prepared jointly by the U.S. Olympic Committee Sports Medicine Division and the International Center for
Sports Nutrition, provides nutrition fundamentals regarding the
calories used during specific levels of activity.
A F T E R
the bell
ACTIVITY 1
Two ways to estimate calories consumed
You can calculate the average amount of energy you require per hour by converting your mass in pounds to kilograms
(multiply by 0.453, the constant for converting pounds to kilograms).
Then, multiply the mass in kilograms by 1.0 for males and 0.9 for females. For example, an individual with a mass of
130 pounds would multiply 130 by 0.453. The result is 58.89. This result is then multiplied by 1.0 for a male (approximately
59 calories per hour) and by 0.9 for a female (approximately 53 calories per hour). These are only averages, and the
burning of calories will depend on the amount of physical activity.
The U.S. Olympic Committee Sports Medicine Division
Calories per pound per day
and the International Center for Sports Nutrition provide
Activity level
Male
Female
an additional way to calculate the calories per pound used
Sleeping or resting
11
10.5
in one day while engaged in activities (see Resources).
Because different activities will require varying energy
Very light
14
13.5
levels, you will need to decide what level of activity you
Light
17
16
conduct for the majority of the day. Activity levels range
Moderate
18.5
17
from very light to heavy (see below).
Heavy
22.5
20
In this part of the activity, you will select a general activity level that relates to your daily routine. Then, calculate the
average number of calories your body burns per day.
For example, Agatha weighs 120 pounds. On most days, she walks to and from school. She is also on the school
swim team and practices approximately one hour
Name of activity and activity level
per day. Agatha often walks to her friend’s house
Name of activity
Activity level
on her way back home. At home, she often helps
her parents complete light household chores. The
Sleeping
Extremely light
rest of the day, Agatha completes her homework
Sitting or standing
Very light
and sleeps. According to the U.S. Olympic
Walking, bowling, golfing
Light
Committee Sports Medicine Division, Agatha would
Jogging,
swimming,
speed
walking
Moderate
be considered within the “light” category, and her
Long distance running, climbing, soccer
Heavy
calorie estimate would be 120 × 16 = 1,920 calories
per day.
ACTIVITY 2
Reading what you eat
For Teachers
Nutrients are water, minerals, carbohydrates, fats, proteins, and vitamins. Each of these substances provides the
body with energy and material for growth. Water is important because it transports nutrients in solution and serves
as a solvent that dissolves food, enzymes, and waste materials.
Minerals are inorganic substances required by the body. Approximately 14 minerals are required for activities
such as chemical reactions, transmission of nerve impulses, the carrying of oxygen to the cells, and cell growth
and maintenance. Calcium and phosphorus are the two most abundant minerals in our bodies. Both calcium
and phosphorus are important minerals for bones and phosphorus is an important element of deoxyribonucleic
acid (DNA).
Carbohydrates provide the body with glucose. Simply put, glucose is a simple sugar that contains carbon, hydrogen,
and oxygen atoms. Carbohydrates, the body’s fuel source, drives all life processes.
Fats are organic molecules that are also composed of carbon, hydrogen, and oxygen, but arranged in different
proportions. Fats serve as a source of stored energy for the body. Certain fats are important for good health. Fats
help to protect vital organs, control dehydration, help dissolve certain vitamins, and are important components of
cellular membranes.
Proteins are an essential component of muscles, skin, and internal organs, and also serve as enzymes that
regulate the rate of chemical reactions in the body. Proteins provide the body with the required building materials for
growth and maintenance. They are complex macromolecules that are composed of carbon, hydrogen, oxygen, and
nitrogen. The subunits of proteins are called amino acids.
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A F T E R
the bell
ACTIVITY 2
Reading what you eat (cont.)
Vitamins are complex molecules required by the body for proper functioning. They serve as catalysts that assist
enzymes in chemical reactions, such as the joining together of amino acids. Although some vitamins such as
D and K can be synthesized by the body, most others can be obtained by eating a balanced diet.
There are additional lessons that can easily be integrated in the topic of nutrition. Students can discuss
their attitudes toward certain food issues, such as super-sizing and the over-processing of food. Students
can also determine how accurately they predict portion sizes, determine the caloric intake from certain foods,
and identify the amount and type of food they will consume within a 24-hour period.
For Students
Food labels list the nutritional information of packaged foods. In this exercise, study the labels to identify what
minerals are present in the foods you are consuming. Then, research and record how these specific minerals
help the body to function.
Minerals like these belong to a group of elements called the metal cations, which are essential in human
nutrition. There are additional minerals, such as iodine (I), chlorine (Cl), fluorine (F), zinc (Zn), and copper
(Cu), which can also be investigated and added to the chart.
Recommended
daily requirement
Nutrients
Health benefits
Types of foods that
contain this nutrient
Stronger bones and
teeth; proper muscle
and nerve function;
blood clotting
Dark green vegetables;
milk and other dairy
products; eggs
Minerals
calcium (Ca)
800 milligrams
sodium (Na)
magnesium (Mg)
iron (Fe)
phosphorus (P)
potassium (K)
Fats
Carbohydrates
Proteins
Vitamins
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