Energy Expenditure Flashcards
(39 cards)
What is the formula for energy balance, and what components does it include?
Energy balance = energy intake - energy expenditure
Components: carbohydrates, lipids, proteins, alcohol (intake), basal metabolic rate, physical activity, thermic effect of food, thermoregulation (expenditure).
How is energy intake assessed, and what methods are commonly used for this purpose?
Assessed through calories consumed.
Methods: 24-hour recalls, food records.
What are the main factors influencing basal metabolic rate (BMR)?
Includes respiration, heartbeat, renal function, muscle tone, blood circulation.
Organs like liver, lung, heart, brain, kidneys contribute to 60-80% of basal metabolism.
Muscle contributes ≤ 25% of basal metabolism.
How is BMR assessed, and what conditions are considered during measurement?
Measured by consumed O2 and produced CO2 under standardized conditions.
Conditions: postabsorptive state, ideally after awakening, lying down, relaxed, motionless, and at a comfortable temperature.
What is Resting Metabolic Rate (RMR), and how does it differ from BMR?
RMR is measured under conditions similar to BMR but without food intake or exercise 4-5 hours before the test.
RMR is 10% higher than BMR, considering the calories needed for digesting foods.
What are the factors influencing BMR and RMR related to age and body composition?
Highest BMR during infancy due to growth.
BMR decreases with maturation.
In adults, BMR decreases with age, influenced by changes in fat-free mass and fat mass.
How does gender impact BMR, and what is the observed difference between men and women?
Men have a 10% higher BMR than females.
Men: 1 kcal/kg/hr; Women: 0.9 kcal/kg/hr due to different body compositions.
What physiological states influence BMR and RMR?
Pregnancy, fever, hyperthyroidism, fasting, menstrual cycle.
Define Thermic Effect of Food (Diet-Induced Thermogenesis).
It’s the metabolic response to food, leading to increased heat production after a meal.
Involves digestion, absorption, active transport, metabolism, and storage of energy from ingested food.
Constitutes 5-30% increase in energy expenditure over BMR.
What are the contributions of different macronutrients to the Thermic Effect of Food?
Greatest effect for protein (20-30% increase in energy expenditure).
Intermediate effect for carbohydrates (5-10%).
Smallest effect for fat (0-5%).
Define Thermoregulation (Regulatory Thermogenesis) and its impact on energy expenditure.
It’s the change in metabolism to maintain or restore the body’s core temperature.
Environmental temperature changes lead to alterations in energy expenditure.
Hypothermia and hyperthermia are examples of extreme responses to environmental temperature changes.
How does environmental temperature impact thermoregulation?
In a cold environment, the body generates heat, contributing to increased energy expenditure.
In a warm environment, reduced muscle tonus and sweating contribute to altered energy expenditure.
What is the role of physical activity in energy expenditure, and how variable is it among individuals?
Physical activity is the most variable component, accounting for 20-40% of total energy expenditure.
It depends on factors like intensity, duration, and frequency of activity.
How are methods like calorimetry used to assess energy expenditure?
Calorimetry involves the determination of body heat loss.
Direct calorimetry measures heat dissipation, while indirect calorimetry measures oxygen consumption and carbon dioxide expiration.
What is Respiratory Quotient (RQ), and how is it used in indirect calorimetry?
RQ = CO2 produced / O2 inhaled.
It’s used to calculate macronutrient composition, with different values for carbohydrates, fat, and protein.
Explain the Doubly Labeled Water method and its application in assessing energy expenditure.
It involves adding stable isotopes to water and measuring their disappearance in blood and urine.
It helps calculate energy expenditure by assessing the turnover rates of labeled oxygen and hydrogen.
Despite its accuracy, it has limitations such as high costs and potential errors in food records.
What are the limitations of direct calorimetry, and why is indirect calorimetry more commonly used?
Direct calorimetry is expensive, laborious, and uncomfortable for subjects.
Indirect calorimetry, measuring oxygen consumption and carbon dioxide expiration, is more practical and less invasive.
What is the significance of the Respiratory Quotient (RQ) in different physiological conditions?
RQ can indicate the form of energy expenditure, such as BMR or thermic effect of food.
Different RQ values represent different macronutrient compositions and metabolic states.
How is the Doubly Labeled Water method applied in assessing energy expenditure, and what are its limitations?
It involves adding stable isotopes to water and measuring their disappearance in blood and urine.
Limitations include the reliance on food records
Define energy balance.
Energy balance is achieved when energy input, derived from food and beverages, equals energy output, which includes metabolism, organ function, regulation of body temperature, and exercise.
What is negative energy balance, and what are its causes?
Negative energy balance occurs when energy intake is less than energy expenditure. Causes include insufficient food availability, anorexia nervosa, bulimia nervosa, and certain medical conditions like cancer.
Explain the female athlete triad and its management.
The female athlete triad involves disordered eating, irregular menstruation, and low bone density, often seen in young female athletes. Management includes reducing preoccupation with food, achieving a healthy weight, and decreasing training intensity.
What characterizes positive energy balance?
Positive energy balance occurs when energy input exceeds output, leading to the gain of adipose tissue, muscle, and weight. It can result from excessive caloric intake, a sedentary lifestyle, or genetic/biochemical factors.
How can exercise impact energy balance?
Exercise contributes to negative energy balance, benefiting weight loss in overweight individuals. However, it may be detrimental to individuals with certain eating disorders or conditions like bulimia nervosa or the female athlete triad.
