Basal Metabolic Rate (BMR) in Nutrition
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Questions and Answers

What percentage of daily energy is used to digest food?

  • 20%
  • 10% (correct)
  • 5%
  • 30%

    • What is the primary purpose of knowing one's basal metabolic rate?

  • To maintain, lose, or gain weight (correct)
  • To track daily energy expenditure
  • To measure resting metabolic rate
  • To monitor physical activity

    • What happens when an individual consumes more calories than their basal metabolic rate?

  • No change in weight
  • Weight gain (correct)
  • Weight loss
  • Increased physical activity

    • How does physical activity affect basal metabolic rate?

    <p>It increases BMR</p> Signup and view all the answers

    What is the primary difference between basal metabolic rate and resting metabolic rate?

    <p>BMR is the minimum energy needed, while RMR is the actual energy expenditure</p> Signup and view all the answers

    What is the primary difference between Basal Metabolic Rate (BMR) and Resting Metabolic Rate (RMR)?

    <p>RMR includes calories needed for eating, sweating, and using the restroom, whereas BMR does not</p> Signup and view all the answers

    What is the purpose of the Mifflin-St.Jeor equation?

    <p>To calculate the Basal Metabolic Rate in humans</p> Signup and view all the answers

    What is the significance of the 'mouse-elephant curve' in calculating BMR in animals?

    <p>It describes the relationship between BMR and body mass raised to the 3/4 power</p> Signup and view all the answers

    What is the difference between mass-specific metabolic rates and whole-organism metabolic rates?

    <p>Mass-specific metabolic rates are reported per unit of body mass, while whole-organism metabolic rates are reported per unit of time</p> Signup and view all the answers

    What is the role of the sympathetic nervous system in measuring BMR?

    <p>It must be deactivated to measure BMR accurately</p> Signup and view all the answers

    What is the primary difference between endotherms and ectotherms?

    <p>Their ability to regulate body temperature</p> Signup and view all the answers

    According to the given data, which of the following organisms has a higher mass-specific metabolic rate?

    <p>A 2-gram mouse</p> Signup and view all the answers

    What is the normal range of variation in basal metabolic rate (BMR) for humans of the same gender, height, and weight?

    <p>-15% to +5%</p> Signup and view all the answers

    Which of the following factors does NOT affect a human's basal metabolic rate (BMR)?

    <p>Blood type</p> Signup and view all the answers

    What is an advantage of being an ectotherm?

    <p>Higher energy efficiency</p> Signup and view all the answers

    Study Notes

    Basal Metabolic Rate (BMR)

    • BMR is the minimum number of calories required for basic bodily functions at rest, such as breathing and circulation.
    • At rest, the body should be at a comfortable temperature and not digesting food.
    • Approximately 70% of daily energy is used to maintain organ function, 10% for digestion, and 20% for physical activity.
    • Understanding BMR aids in weight management; consuming more calories than BMR leads to weight gain, while consuming less results in weight loss.
    • Activity levels significantly influence BMR, with more active individuals having a higher BMR than inactive individuals.

    Resting Metabolic Rate (RMR)

    • RMR is sometimes used interchangeably with BMR but refers to the number of calories burned at rest including more than life-sustaining functions.
    • Activities included in RMR measurements are eating, sweating, shivering, and using the restroom.
    • The conditions for measuring BMR are stricter than for RMR, requiring the sympathetic nervous system to remain inactive.

    Biological Definition of BMR

    • BMR in biology defines the continuous supply rate of some chemical or process, focusing on the allometric relationship between body mass and metabolic rate.
    • Allometry, describing the relationship of body size to shape, was first detailed by Otto Snell in 1892.

    Calculating Basal Metabolic Rate

    • The Mifflin-St. Jeor equation, introduced in 1990, is commonly used to calculate human BMR.
    • The formula includes weight (kg), height (cm), age (years), and a constant based on gender (+5 for males, -161 for females) due to muscle mass differences.
    • Example BMR calculation for a 30-year-old woman (5'3", 130 lbs) results in 1,263.4 calories for maintenance, while her RMR would be approximately 1,375.6 calories.

    BMR Calculation in Animals

    • BMR in mammals can be assessed using respirometry to measure oxygen consumption.
    • Dr. Max Kleiber’s discovery outlines that BMR closely correlates with mass raised to the 3/4 power, illustrated by the mouse-elephant curve.
    • A 2-gram mouse has a BMR of 0.009, whereas a 2-kilogram elephant has a BMR of 1.68, highlighting metabolic differences across species.

    Variance in BMR

    • Normal BMR range for humans is between -15% to +5%, indicating individual differences even among similar demographics.
    • Factors affecting BMR include age, genetics, weather, diet, pregnancy, and supplementation.
    • BMR is influenced by temperature; endotherms (mammals) require energy to maintain a constant body temperature, while ectotherms (reptiles, fish, insects) have fluctuating temperatures based on the environment.

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    Description

    Learn about the concept of Basal Metabolic Rate (BMR), its definition, and how it affects our daily energy expenditure. Understand the percentage of energy used for different bodily functions.

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