Question

A 12 -oz can of most colas has about 120 nutritional calories \((1\) nutritional calorie \(=1 \mathrm{kcal}) .\) Approximately how many minutes of walking are required to burn up as energy the calories taken in after drinking a can of cola? (Walking uses up about \(250 \mathrm{kcal} / \mathrm{h} .)\)

Short answer

Answer: It takes approximately 28.8 minutes of walking to burn off the energy from a 12-oz can of cola containing 120 kcal.

Step-by-step solution

Understand the given information and convert units if needed

We are given that a 12-oz can of cola contains 120 nutritional calories. One nutritional calorie is equal to 1 kcal. Therefore, a can of cola contains 120 kcal. We're also given that walking burns 250 kcal/h. Since we need to find the time in minutes, we must first convert kcal/h to kcal/min.

Convert kcal/h to kcal/min

To convert from kcal/h to kcal/min, divide the value by 60 as there are 60 minutes in an hour: \(\frac{250\text{ kcal}}{1\text{h}} \cdot \frac{1\text{h}}{60\text{min}} =\frac{250}{60}\text{ kcal/min}\) Now we have the energy burnt in walking per minute, which is approximately 4.17 kcal/min.

Calculate the number of minutes needed to burn 120 kcal

Now that we have the rate of energy spent per minute of walking (4.17 kcal/min), we will calculate the number of minutes needed to burn 120 kcal. We will set up a proportion: \(\frac{\text{Energy burned walking}}{\text{Energy of cola}} = \frac{\text{Walking rate}}{\text{Minutes of walking}}\) \(\frac{250\text{ kcal}/\text{60 min}}{120\text{ kcal}} = \frac{1}{\text{Minutes of walking}}\) Now, we'll solve for the "Minutes of walking": \(1 = \frac{120\text{ kcal} \cdot 60\text{ min}}{250\text{ kcal}}\) \(\text{Minutes of walking} = \frac{60 \cdot 120}{250}\) \(\text{Minutes of walking} \approx 28.8\) So it would take approximately 28.8 minutes of walking to burn off the energy taken in after drinking a can of cola.

Key concepts

Energy Expenditure

When we talk about energy expenditure, we're referring to the number of calories burned by the body to sustain basic physiological functions and physical activity. Calculating energy expenditure is important for managing weight and understanding the balance between caloric intake and caloric usage.

Energy expenditure is often measured in kilocalories (kcal), with one kilocalorie being equivalent to the amount of heat required to raise the temperature of one kilogram of water by one degree Celsius. The Total Daily Energy Expenditure (TDEE) is the cumulative number of calories burned in a day and includes resting metabolic rate (RMR), calories burned through daily activities, and structured exercise.

Solving the textbook exercise involves understanding the energy expenditure from walking, an activity which, in this context, burns approximately 250 kcal per hour. In order to personalize this information, students should consider factors such as body weight, walking speed, and physiology, which all affect the actual calories burned during physical activities like walking.

Nutritional Calorie

A nutritional calorie, commonly just called a calorie, is a unit of energy that is used to measure the energy content of foods and beverages. Technically, a nutritional calorie is equivalent to a kilocalorie (kcal) and is defined as the amount of heat needed to raise the temperature of one kilogram of water by one degree Celsius at one atmosphere of pressure.

It is important for students to recognize that the calorie content indicated on food packages refers to nutritional calories (kcal). In the given exercise, a 12-oz can of cola is said to contain about 120 nutritional calories (or 120 kcal). Understanding how to equate calories consumed through foods and drinks to calories burned through physical activities is essential for maintaining a balanced diet and lifestyle.

Moreover, when considering nutritional information, it is also valuable to be aware of the quality of the calories ingested, as different foods have varying effects on satiety, metabolism, and overall health, despite their calorie counts.

Physical Activity

The term physical activity encompasses any body movement produced by skeletal muscles resulting in energy expenditure. Broad examples include walking, running, cycling, swimming, and many other forms of exercise and everyday movements. Regular physical activity is crucial for maintaining overall health and can contribute to weight management, improved cardiovascular health, and strengthened muscles and bones.

In our exercise scenario, walking is the physical activity used to demonstrate the concept of energy expenditure. Walking typically expends 250 kcal per hour, which is a moderate rate when compared to other activities. To optimize understanding of the calorie burning process during physical activity, students should know that variables such as intensity, duration, and an individual's body composition can significantly impact total energy expenditure. These factors should be taken into account when applying calculations from textbook exercises to real-life scenarios.