Calories In, Calories Out : A Lesson by Mathalicious

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How many calories does a body burn each day, and how many does it need? We know that exercise is one way to burn calories, but is it the only way? Is it even the main way?

In this lesson, students learn the math behind eating and exercise. They use unit rates and expressions to calculate how many calories our bodies burn from exercise, and how many they burn automatically. Finally, they combine this with food and come up with a plan to help someone lose weight.

Students will

For a given exercise, calculate number of calories someone will burn in m minutes
Use formula for resting metabolic rate to calculate number of calories person will burn automatically
Given 2000-calorie daily intake, explain how excess calories eaten/burned will translate into weight gain/loss
Given a menu of foods, come up with diet that will help someone maintain healthy weight

Before you begin

For males, the formula for resting metabolic rate is RMR = 4.5w + 15.9h – 5a + 5, where w represents weight in pounds, h represents height in inches, and a represents age in years. (The formula is slightly different for women.) While this formula is by no means overly complicated, it would be helpful if students were already familiar with substituting values and evaluating expressions.

Note: Approximately 1 in 3 American children are overweight or obese, while many others struggle with eating disorders. To avoid insecurities, teasing, etc., the lesson does not ask students to calculate their own caloric intake. Instead, it does its best to treat the human body as fundamentally no different than a car or any other machine: something that requires fuel to burn. The goal is for students not only to understand the math behind eating and exercise, but also to remove some of the stigma behind it. Still, before beginning the lesson, you might remind students that this is a sensitive topic for millions of people across the country, and that you expect their behavior to demonstrate understanding and empathy.