In this lesson, students pick out a full day's worth of meals from a
McDonald's menu with an eye towards the Zone Diet, which specifies
percentages of fat, carbohydrates, and protein. The gist of the Zone
Diet is that whenever you eat, you should strive to consume
40% carbohydrates, 30% protein and 30% fat. As a result, this diet has
also been referred to as the 40‑30‑30 diet.
Many sources indicate that an average person requires about
2,000 calories per day. That number varies based on several factors,
but is used as the target for this lesson. To prepare for the lesson,
you might research some details on the Internet. For example, you can
find out what various athletes consume in a day. You will find that
it's much more than 2,000 calories. There was an urban legend floating
around for a while that Michael Phelps (Olympic swimming gold medalist)
was consuming 12,000 calories per day. That turned out to be untrue,
but it might be interesting to start things off with a classroom
discussion regarding how many calories various athletes consume. That
could lead into a discussion regarding whether students know how many
calories they consume and what proportion of nutrients are contained in
the foods they eat.
Another lesson opener could be the portrayal of diet in the
media. Some students may have seen the movie Supersize Me. Discuss the
nutritional concerns about eating fast food. This can naturally
progress into a discussion of diets. Suggest the idea of being "in the
Zone." Ask whether any students have noticed a relationship between
what they eat and how they feel. Do they sometimes feel sleepy? hyper?
or just right?
Depending on time, you may wish to have a longer discussion
about nutrition. If you choose to do this, you may wish to share the
following information on nutrients with students:
- Carbohydrates: our main source of energy
- Fats: one source of energy and important in relation to fat soluble vitamins
- Minerals: inorganic elements that are critical to normal body functions
- Proteins: essential to growth and repair of muscle and other body tissues
- Roughage: the fibrous indigestible portion of our diet essential to health of the digestive system
- Vitamins: important in many chemical processes in the body
- Water: essential to normal body function, both as a vehicle
for carrying other nutrients and because around 60% of the human body is water
In nutrition, some information focuses on food weight and other
information focuses on calories. Make students aware of this before
they begin the activity to help them avoid errors based on these units.
There is not a one-to-one relationship between food weight and
calories. The Zone Diet percentages are all with regard to calories, so
if you only have weight information, you need to convert to calories to
match the Zone Diet percentages.
Fortunately, the conversions between food weight and calories
are simple and students may have already studied this information in
physical education or health class. Here are the conversions, which are
also provided on the activity sheet:
- Fat: 1 gram = 9 calories
- Carbohydrates: 1 gram = 4 calories
- Protein: 1 gram = 4 calories
This information can be written on the board or put up via a transparency.
Hand out the Big Math and Fries Activity Sheet and calculators.
Big Math and Fries Activity Sheet
For this lesson, students should use
calculators because of the number of calculations required. You can
choose how many decimal places that they should round to. Just remember
that some of their calculations will be converted from decimal to
percent, so they'll need at least two decimal places for those
calculations. Students should also be given McDonald's nutrition facts.
You can either hand out paper copies or display McDonald's nutrition information via a computer projector (conduct a simple Internet search to find this information).
Have students read the McDonald's nutrition information, and try to
pick out enough food so that the total number of calories adds up to
2,000 for the day. It is difficult to meet all the caloric and Zone
diet requirements at once, so suggest to students to begin with only
one or two. Students can attempt to ensure that their percent of
calories from fat for the day is less than 30%. If students can do
that, they've done well. Then challenge students who succeed to
additional goals, such as keeping carbohydrates to 40% of the total
calories and keeping protein to 30% of the total calories. It is
difficult to achieve all three, but students should be able to keep fat
under 30%. More advanced students may be able to get close to the
proper percentage for all three nutrients. When more advanced students
finish, have them help slower students who are not finished yet.
A nice wrap-up for this lesson would be to have students that
came closest to achieving Zone proportions present their findings and
explain how they achieved their results. You might also have students
could create posters to present their findings and explain why they
would recommend the meal combinations that they came up with.
Questions for Students
1. Were you able to stay under 30% for total calories from fat? Do you feel that you designed a healthy day of eating?
[Answers will vary]
2. What steps did you take in order to meet the requirements of 2,000 calories total and a 40-30-30 ratio?
[Answers will vary. What you're looking for are the
strategies that students used to try to balance the results. For
instance, did successful students focus on one nutrient, get the
appropriate percentage and then change one food item to balance the
other nutrients? Did they first calculate the total amount of grams
needed for each nutrient base on a 2,000 calorie diet and then work
backwards? Or did they come up with something new and unique?]
3. If you were not able to meet the Zone Diet requirements of
40-30-30, could you tweak a few items to change that? If so, which
items would you change and how does that improve your
carbohydrates-protein-fat ratio for the day?
[Students should look at nutrient percentages that are too
high and try to figure out which items they could remove or replace in
order to get better ratios.]
4. Would it be easier to design one Zone friendly meal and, if so, which items would you choose?
[Yes, it would probably be easier to design just one meal
to meet the ratios. This should lead students to think about balancing
nutrient ratios when they go to eat a meal or a snack.]
5. If you were to design the McDonald's nutrition pamphlet, what would you change from the current design?
[Answers will vary. One suggestion might be to provide percentage of each nutrient, not just fat.]
- Were most students able to adjust their food choices to achieve
Zone proportions? If not, what problems did they run into? How could
these problems be avoided?
- Were any students confused about the difference between
calculating the calories due to the nutrient weights and calculating
the percent of calories from a particular nutrient? If so, how could
this confusion be avoided in the future?
- Were students motivated to achieve Zone proportions or did they just pick various menu items to get the work part over with?
- Did students feel that this lesson was interesting or of use to them?
- Mathematically analyze the food they eat.
- Identify the relationship between nutrients and the calories.
- Perform calculations, including percents and conversions.
NCTM Standards and Expectations
- Work flexibly with fractions, decimals, and percents to solve problems.
- Understand and use ratios and proportions to represent quantitative relationship.
- Develop, analyze, and explain methods for solving problems involving proportions, such as scaling and finding equivalent ratios.
Common Core State Standards – Mathematics
Grade 7, The Number System
Solve real-world and mathematical problems involving the four operations with rational numbers.
Common Core State Standards – Practice
Make sense of problems and persevere in solving them.