L3 energy balance
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Transcript of L3 energy balance
Usable power
Derived from stored chemical energy in foods we eat
Allows people to:
power bodies
produce heat
Energy balance:
• relationship between energy intake and energy used by the body
• Energy expenditure:
• energy used by the body
Measurement of chemical form of energy in foods
Amount of energy needed to raise temperature of 1,000 g of water by 1º C
Mistakenly called calories
Bomb calorimeter measures kilocalories
Kilojoule: Amount of energy needed to move 1 kg with an acceleration of 1 meter per second
Metabolism of carbohydrate, protein, fat, and alcohol
End products of carbohydrate, protein, and fat metabolism:
carbon dioxide
water
energy in the form of ATP
End products of alcohol metabolism:
some of the same by-products
long-chain fatty acids
Simple calculations based on basic knowledge
Scientific databases contain analyses based on:
laboratory studies
manufacturer information
Availability and use of software programs based on these databases
Comprised of several components
Unique for each person
Measured indirectly or calculated using equations
Total energy expenditure:
processes in the body
physical activity
Energy required for vital functions in body at rest
Basal energy expenditure:
expression of basal metabolism as kcalories over 24 hours
different from resting energy expenditure
heavier individuals have higher resting metabolic needs
gender differences due to muscle mass and organ size
debates on relationship to age
Energy expended for body temperature regulation
varies based on surface area to weight ratio
thermoregulation challenges alter energy use
adjust energy expenditure calculations when thermoregulation issues occur
impact of extreme ambient temperatures
with normal conditions, little change
Increased needs with infancy, childhood, adolescence, pregnancy, and lactation
A person’s metabolic rate is dependent on many things, including physical activity and the amount of muscle.”
The metabolic rate is influenced by the activity level, the amount of muscle mass, and body temperature, among other things. Muscle and organ tissue is more metabolically active than fat, so if the person who is overweight has more fat mass, the basal metabolic rate may be slower than someone of the same weight who has more muscle mass.
However, people will not become overweight if they have high metabolic rate. Increasing physical activity will help develop more muscle mass, which is more metabolically active.No two individuals will have exactly the same metabolic rate.
Metabolic cost of digestion, metabolism, and storage of nutrients
Typically 10% of every value of the food
Protein thermic effect: 20 to 30%
Alcohol thermic effect: up to 13%
Fat thermic effect: less than 5%
Thermogenesis
Physical component of energy expenditure
actual exercise
nonexercise activity
NEAT:
any activity involving muscle contraction
activities of daily living
Energy expended depends on activity intensity and duration
• Usually expressed as a ratio or percentage of basal energy expenditure
• Laboratory measurements:
–calculate kcalories used per minute of activity for various body weights
–heavier person expends more energy in same activity than a lighter person
Predictive equations:
estimate energy intake
equations based on height, weight, gender, and age
high margin of error
based on healthy, normal weight individuals
altering equations leads to more inaccuracies
no established equation for older population
Relationship between energy intake and energy expenditure
Balance fosters weight maintenance
Negative energy balance:
insufficient energy to support needs
causes: insufficient intake and/or increased expenditure
Positive energy balance:
energy intake exceeds needs
causes: increased intake and/or decreased expenditure
Individual differences
Influence of biology and other factors on appetite, satiety, and metabolism
Low levels of activity prevalent
Increased intake widespread
Goals of national recommendations:
reduce obesity
provide adequate energy
Estimated Energy Requirements:
recommendations for population groups
role of registered dietitian
no advice supporting weight loss/weight gain
Excess energy consumption compared to needs
Interventions when weight gain increases disease risk
Target energy consumption or expenditure contributing to imbalance
Nurse’s role in intervention:
explore sources of kcalories and “empty” calories
brainstorm ways to create deficit
find opportunities for physical activity
Socioeconomic levels tied to positive energy balance
Importance of education
A positive energy balance results from caloric intake exceeding energy expenditure, ultimately leading to weight gain. Children who do not engage in much physical activity tend to have a higher weight than those who are active. Impaired glucose tolerance may result when there is excess weight but it tends to develop over a period of years.
Result of insufficient energy consumption and/or excess physical activity
Intervention necessary when health risks increase
Target aspects of consumption or expenditure contributing to imbalance
Team approach
Nutrition assessment
Assessment of physical activity levels
Elevation of metabolic response
Avoidance of predictive equations
Use of indirect calorimetry or modified approach