Question

One way to lose weight is to exercise! Walking briskly at 4.0 miles per hour for an hour consumes about 400 kcal of energy. How many hours would you have to walk at 4.0 miles per hour to lose one pound of body fat? One gram of body fat is equivalent to 7.7 kcal of energy. There are 454 g in 1 lb.

Short answer

You would have to walk for approximately \(8.7 \, hours\) at 4.0 miles per hour to burn one pound of body fat.

Step-by-step solution

Determine the energy required to burn one pound of body fat

First, we need to find out how much energy in kcal is required to burn one pound of body fat. To do this, we will multiply the number of grams in 1 lb (454 g) by the energy equivalent of 1 gram of body fat (7.7 kcal). \[454 \, g \times 7.7 \, kcal/g = 3,495.8\, kcal\] So, 3,495.8 kcal of energy is required to burn one pound of body fat.

Calculate the number of hours required to burn one pound of body fat

Now, we will divide the total energy required to burn one pound of body fat, which we found in Step 1 (3,495.8 kcal), by the energy consumed per hour while walking briskly at 4.0 miles per hour (400 kcal/hour): \[\text{Hours Needed} = \dfrac{3,495.8\, kcal}{400 \, kcal/hour} = 8.7395 \, hours\]

Round to a reasonable value

It would be more practical to round our result to one decimal place. It also makes the answer more readable. \[8.7395 \, hours \approx 8.7 \, hours\] So, you would have to walk for approximately 8.7 hours at 4.0 miles per hour to burn one pound of body fat.

Key concepts

Caloric Expenditure

When we talk about caloric expenditure, we are referring to the amount of energy, measured in calories, that your body uses. This energy is spent on day-to-day activities and bodily functions. Exercising increases this expenditure because your body needs more energy to sustain the physical activity involved. For example, walking briskly for an hour at a speed of 4.0 miles per hour burns about 400 calories. This is an effective way to increase your caloric expenditure if you're looking to lose weight.

Calculating your daily caloric expenditure can help you understand how many calories you consume versus how many you burn. By maintaining a calorie deficit (burning more calories than you consume), your body will rely on stored energy, such as body fat, to make up the difference, leading to weight loss.

• Daily activities and exercises contribute to higher caloric expenditure.
• Caloric expenditure can be tracked to manage weight loss effectively.

Energy Conversion

Energy conversion is the process of changing energy from one form to another. In the context of weight loss and exercise, it is particularly important in understanding how our body transforms stored body fat into usable energy when exercising. When you walk briskly and consume 400 kcal per hour, your body is converting stored energy into kinetic energy for movement.

This conversion is key to burning calories. It starts with breaking down glucose and fats during exercise. The energy from these molecules is used to fuel muscular activity and bodily functions. By converting stored fat into energy, you help reduce your body's fat reserves.

• Energy conversion is central to the process of burning stored fat.
• The body uses chemical reactions to convert fats and glucose into energy during exercise.

Body Fat

Body fat is essential for storing energy, cushioning organs, and regulating body temperature. However, excess body fat can lead to health issues. Understanding the energy value of body fat can help in weight management. One gram of body fat equals 7.7 kcal. Thus, a pound of body fat, composed of 454 grams, represents approximately 3,495.8 kcal.

When you aim to lose weight, the goal is to create a caloric deficit, leading your body to break down these fat reserves for energy. This process reduces body fat, which is particularly beneficial for improving overall health.

• Body fat serves as an energy reserve for the body.
• Managing body fat levels is crucial for maintaining health.

Walking and Fitness

Walking is a simple, accessible form of exercise that offers numerous health benefits. It is effective for weight loss due to the calories burned during the activity. Walking briskly at 4.0 miles per hour can burn 400 kcal in just one hour, making it a great choice for increasing physical activity levels.

Besides aiding in weight loss, walking increases cardiovascular fitness, strengthens muscles, and can improve mood. Developing a regular walking routine can contribute significantly to your fitness goals. To maximize benefits, consistency and gradual progression in intensity or duration are key.

• Walking is a low-impact exercise suitable for most fitness levels.
• Regular walking sessions can significantly contribute to fitness and weight loss.