Ch. 22 - Metabolism and Energy Balance

Introduction

This tutorial provides a comprehensive overview of metabolism and energy balance, based on insights from the BYUH BIOL261 video. Understanding these concepts is essential for studying biological processes and maintaining a healthy lifestyle.

Step 1: Understand Metabolism

• Metabolism refers to all chemical reactions that occur within the body to maintain life.
• It can be divided into two main categories:
  • Catabolism: The breakdown of molecules to obtain energy. For example, the digestion of food.
  • Anabolism: The synthesis of all compounds needed by the cells. This includes processes like muscle building.

Practical Tip

Focus on foods that support both catabolic and anabolic processes, such as proteins for muscle synthesis and carbohydrates for energy.

Step 2: Explore Energy Balance

• Energy balance is the relationship between the energy consumed through food and the energy expended through physical activity.
• It can be categorized into three states:
  • Positive Energy Balance: Consuming more calories than expended, leading to weight gain.
  • Negative Energy Balance: Expending more calories than consumed, leading to weight loss.
  • Neutral Energy Balance: Consuming calories equal to those expended, maintaining weight.

Common Pitfall

Be mindful of hidden calories in beverages and snacks, which can easily tip the balance toward a positive energy state without realizing it.

Step 3: Recognize the Role of Basal Metabolic Rate (BMR)

• BMR is the number of calories your body needs to maintain basic physiological functions at rest.
• Factors influencing BMR include:
  • Age
  • Gender
  • Muscle mass
  • Hormonal levels

Practical Advice

To estimate your BMR, you can use the Mifflin-St Jeor Equation:

• For men:

  BMR = 10 * weight(kg) + 6.25 * height(cm) - 5 * age(y) + 5
  

• For women:

  BMR = 10 * weight(kg) + 6.25 * height(cm) - 5 * age(y) - 161
  

Step 4: Assess Total Daily Energy Expenditure (TDEE)

• TDEE accounts for all calories burned in a day, factoring in BMR and physical activity.
• To calculate TDEE:
  • Multiply BMR by an activity factor based on your lifestyle:
    • Sedentary (little or no exercise): BMR x 1.2
    • Lightly active (light exercise/sports 1-3 days/week): BMR x 1.375
    • Moderately active (moderate exercise/sports 3-5 days/week): BMR x 1.55
    • Very active (hard exercise/sports 6-7 days a week): BMR x 1.725
    • Super active (very hard exercise/physical job & exercise 2x/day): BMR x 1.9

Step 5: Apply Knowledge for Weight Management

• To achieve weight loss, create a caloric deficit by:
  • Reducing caloric intake
  • Increasing physical activity
• For weight gain, aim for a caloric surplus by:
  • Increasing caloric intake
  • Reducing physical activity if necessary

Real-World Application

Keep a food diary to track your calorie intake and expenditure to help achieve your desired energy balance.

Conclusion

Understanding metabolism and energy balance is crucial for managing weight and overall health. By following these steps, you can calculate your BMR and TDEE, allowing you to make informed decisions about your dietary and exercise choices. Consider these guidelines as a foundation for a healthier lifestyle and explore further resources for in-depth knowledge.