📚 Part 1: Understanding Energy Balance

1. Energy balance occurs when energy intake equals energy output. Which statement best describes a positive energy balance?

Energy intake is less than energy output

Energy intake equals energy output

Energy intake is greater than energy output

Energy output stops completely

2. Which factors affect your Basal Metabolic Rate (BMR)? Select all that apply:

Age

Body size and composition

Gender

What you ate for breakfast

Genetics

3. Fill in the blanks: Your body uses energy for three main purposes: _________ metabolic rate (energy for basic body functions), _________ activity (planned exercise), and _________ activity thermogenesis (fidgeting, posture).

4. A kilojoule is a unit of energy. Approximately how many kilojoules does the average teenager need per day?

2,000-3,000 kJ

6,000-8,000 kJ

8,000-12,000 kJ

15,000-20,000 kJ

🏃 Part 2: Metabolism and Physical Activity

5. Explain the difference between aerobic and anaerobic metabolism. Include which energy systems your body uses for each type.

6. Match the physical activity with its approximate energy expenditure per hour for a 60kg teenager:

Walking (moderate pace)

Swimming (freestyle)

Basketball

Sitting/studying

2,500 kJ/hour

1,200 kJ/hour

400 kJ/hour

2,100 kJ/hour

7. Sarah is a 15-year-old who plays netball 3 times per week and walks to school daily (20 minutes each way). Describe how her energy needs would differ from someone of the same age who is sedentary. Include at least two specific reasons.

⚖️ Part 3: Applying Energy Balance Principles

8. Calculate this energy balance scenario: Jake consumes 10,500 kJ in food during one day. His BMR uses 7,200 kJ, he burns 1,800 kJ during football training, and 600 kJ through other daily activities. What is his energy balance for the day?

Energy balance = _________ kJ

9. List three healthy strategies a teenager could use to maintain energy balance if they wanted to avoid weight gain:

10. Explain why 'crash diets' that severely restrict energy intake are not recommended for teenagers. Include the effects on metabolism in your answer.