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Questions and Answers
Which macronutrient provides the highest amount of energy per gram?
Which macronutrient provides the highest amount of energy per gram?
What is the impact of thyroid hormones on basal metabolic rate (BMR)?
What is the impact of thyroid hormones on basal metabolic rate (BMR)?
How does body surface area influence BMR?
How does body surface area influence BMR?
Which factor is known to decrease the basal metabolic rate (BMR)?
Which factor is known to decrease the basal metabolic rate (BMR)?
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What happens to metabolic rate as a person ages?
What happens to metabolic rate as a person ages?
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What is the definition of basal metabolic rate (BMR)?
What is the definition of basal metabolic rate (BMR)?
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What does energy balance refer to?
What does energy balance refer to?
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Which of the following does NOT contribute to a person's energy output?
Which of the following does NOT contribute to a person's energy output?
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What is a kilocalorie (kcal)?
What is a kilocalorie (kcal)?
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Which nutrient is NOT a direct source of calories for the body?
Which nutrient is NOT a direct source of calories for the body?
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Study Notes
Energy and Metabolism
- Metabolism refers to the chemical reactions in the body that release energy from food.
- A calorie is a unit of heat energy.
- Kilocalories (kcal) are used to express the energy in food.
- One gram of carbohydrates, protein, and fat contain 4, 4, and 9 kcal respectively.
- The basal metabolic rate (BMR) is the amount of energy required to maintain essential bodily functions at rest.
Energy Balance
- Energy balance is the relationship between energy intake and energy expenditure.
- Factors affecting energy expenditure include physical activity, BMR, and specific dynamic action (SDA).
- SDA is the extra energy used by the body to process food.
Factors Affecting BMR
- Body surface area: Taller people have higher BMRs.
- Sex: Males have higher BMRs due to a greater lean body mass.
- Body temperature: Fever increases BMR
- Hormones: Thyroid hormones stimulate metabolism leading to higher BMR in hyperthyroidism and lower in hypothyroidism.
- Age: BMR declines with age.
- Diet: Starvation or calorie restriction significantly reduces BMR.
- Pregnancy/breastfeeding: Increase metabolic rate.
- Environment: Cold climates result in higher BMR compared to warm climates.
- Rapid growth & development: Infancy, growth spurts, recovery from illness or injury increase BMR
- Disease states: BMR is higher in certain conditions like cardiac failure, leukemia, and hypertension.
- Weight: Higher weight leads to higher BMR.
- Exercise: Regular exercise builds lean tissue which raises BMR and results in higher calorie expenditure.
Body Weight and Body Mass Standards
- Ideal body weight refers to the optimal weight for good health.
- Body Mass Index (BMI) is a more reliable indicator of healthy weight, based on height and weight.
- BMI is calculated by dividing weight in kilograms by the square of height in meters.
- BMI is a general indicator and may not be accurate for individuals with fluid retention, athletes, or the elderly.
Caloric Needs
- Total Daily Energy Expenditure (TDEE) is the total number of calories burned by the body in 24 hours.
- Calculating TDEE involves accounting for BMR, physical activity, and SDA.
- Example calculations for individuals with varying levels of work demonstrate the energy requirements for different daily activities.
- The caloric requirements for different work types are:
- Light work: 2100-2600 kcal/day
- Moderate work: 2500-3000 kcal/day
- Heavy work: 3000-3500 kcal/day
- Very heavy work: 3500-4000 kcal/day
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Description
Test your knowledge on energy, metabolism, and factors affecting basal metabolic rate (BMR). This quiz covers essential concepts like energy balance, caloric content, and the physiological factors influencing metabolism. Perfect for students studying biology or health sciences.
