1. Chapter 6 Energy Balance Ask the students to define the term balance.
Ask how this definition would relate to energy in the body.

2. Chapter 6
Lesson 6.1
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3. Key Concepts
Food energy is changed into body energy and cycled throughout the body to do work.
The body uses most of its energy supply for basal metabolic needs.
How is food energy changed into body energy?
Explain the forms of energy, including adenosine triphosphate, glycogen, and fat.
What happens if there is an imbalance between intake of food and output of work?
Explain that energy balance can be over an hour, a day, a week, and so forth. It is normal to overeat at times and undereat at times.
What diseases can lead to body energy imbalances?
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4. Basic Energy Needs
The body needs constant energy for voluntary and involuntary activity
Voluntary work and exercise
Includes all physical actions related to usual activities and additional physical exercise
Seems to require most of the energy output, but is usually not the case
Explain that because the body needs constant energy, without storage of energy we would need to be eating constantly.
How does a sedentary lifestyle affect body energy balance?
List some common voluntary activities with the students’ help.
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5. Basic Energy Needs, cont’d
Involuntary work: includes all activities of the body that are not consciously performed
Circulation, respiration, digestion, absorption
Requirements include:
Chemical energy: in many metabolic products
Electrical energy: in brain and nerve activities
Mechanical energy: in muscle contraction
Thermal energy: to keep the body warm
Does voluntary or involuntary work demand the greatest energy requirements? Why?
Ask the students to remember what they learned about the digestive system. What are some involuntary movements made after swallowing food?
Provide examples of body systems involved in each type of energy.
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6. Basic Energy Needs, cont’d
Fuel is provided in the form of nutrients
Only three energy-containing nutrients:
Carbohydrate is primary fuel
Fat assists as storage fuel
Protein is a back-up fuel source
Alcohol also provides energy but is not a nutrient
To maintain health, the average daily food energy intake should equal the daily body energy needs.
Why is protein used only when carbohydrate and fat stores are inadequate?
Why is alcohol not considered a nutrient?
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7. Measurement of Energy
Calorie: Amount of energy in food or expended in physical actions
Kilocalorie (1000 calories or 1 Calorie): Amount of heat necessary to raise 1 kg of water 1° C
Large Calorie unit used in nutrition science to avoid dealing with large numbers
Abbreviation: kcalorie or kcal or Cal
Why is kilocalorie the preferred term in nutrition science?
Ask the class to explain the difference between calorie and Calorie in their own words.
The joule is used internationally as the unit of energy measurement.
How are kilocalories converted to kilojoules (kJ)? 1 kcal = kJ
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8. Fuel Factors Carbohydrate: 4 kcal/g Fat: 9 kcal/g Protein: 4 kcal/g
Alcohol: 7 kcal/g
What is the caloric value of 5 g of carbohydrate?
10 g of fat?
30 g of protein?
40 g of alcohol?
Explain why fat is the best storage form of energy. Mention the caloric density of fat and that if the body’s major form of energy storage were protein or carbohydrate, it would take a much larger space to store the same amount of energy.
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9. Caloric and Nutrient Density
Density: The degree of concentration of material in a given substance
Caloric density: Concentration of energy in a given amount of food
Foods high in fat have the highest caloric density
Nutrient density: Concentration of all nutrients in a given amount of food
To help students understand density, use the example of a box full of feathers next to a box full of marbles. Both boxes are the same size, but one is more dense than the other.
Explain that density can be both good and bad. Nutrient-dense foods are usually better than calorie-dense foods, although a food may be both.
List examples of nutrient-dense and calorie-dense foods.
Ask students to consider the nutrient density of the foods they ate at breakfast. Is their diet balanced among the various nutrients?
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10. Chapter 6
Lesson 6.2
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11. Key Concepts
A balance between intake of food energy and output of body work energy maintains life and health.
States of being underweight and overweight reflect degrees of body energy imbalance.
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12. Energy Balance Two energy systems support human life
External energy cycle: Plants transform radiation from the sun into stored chemical energy (carbohydrates, proteins, and fats)
Internal energy cycle: Animals, including human beings, use the stored chemical energy for body needs
Explain why these are called “cycles.” Mention water, carbon dioxide, and heat energy.
Ask the students to explain the difference between external energy and internal energy.
Explain that energy is stored in the bonds of nutrients.
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13. Energy Intake
The body’s energy balance depends on energy intake in relation to energy output
Energy intake
Three macronutrients are stored as:
Glycogen
Adipose tissue
Muscle mass
Energy intake is the calculated energy value of actual food consumption
Stored energy is used when food is not available.
How does the body supply energy during sleep? Glycogen stored in the liver and muscles maintains normal blood glucose levels during sleep.
Where in the body is glycogen stored? Liver and muscles
How long does the glycogen store typically last? 12 to 48 hours
Ask students to think about their energy intake over the last 24 hours. How many think they are in energy balance?
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14. Energy Output
Activities to sustain life require energy from food and body reserves
Three demands for energy determine the body’s total energy requirements
Resting energy expenditure (REE)
Physical activity
Thermic effect of food (TEF)
Chemical changes occurring during these activities are called metabolism.
Exchange of energy in overall balance is usually expressed in kilocalories.
The TEF also is the energy required during digestion.
Of the three demands for energy, which requires the most energy? Resting energy expenditure—liver, brain, heart, kidneys, and gastrointestinal tract—accounts for 60% to 75% of basal metabolic needs.
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15. Resting Energy Expenditure
Sum of all internal working activities of the body at rest
Expressed as kcal/day
Basal energy expenditure (BEE) is similar to REE but requires complete physical rest (difficult to achieve)
An individual with an REE of 1500 kcal/day would need to consume that amount of energy over a 24-hour period to maintain current weight while at complete rest.
What is the difference between REE and BEE? REE refers to all internal working activities of the body at rest; BEE is measured when an individual is at complete digestive, physical, and emotional rest.
Which organ systems use much of the body energy for their cellular functions? Liver, brain, heart, kidneys, and gastrointestinal tract
How does this requirement compare to their overall total body weight? These organs amount to less than 5% of body weight.
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16. Measurement of Resting Metabolic Rate
How are resting metabolic rate (RMR) or basal metabolic rate (BMR) measured?
Indirect calorimetry
Metabolic rate calculated on the basis of the rate of oxygen utilization
Thyroid function test
Measures the activity of the thyroid gland and the blood levels of the hormone thyroxine
What is indirect calorimetry? Measurement of the amount of energy a person uses at rest
Where is indirect calorimetry usually performed? The subject breathes into a mouthpiece or ventilated hood system while lying down.
What does the thyroid gland help regulate?
Explain the relation of iodine to thyroxine and how this hormone affects metabolism.
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17. Measurement of Resting Metabolic Rate, cont’d
General formula
Men
1 kcal x kg body weight x 24 hours
Women
0.9 kcal x kg body weight x 24 hours
What is the conversion factor for pounds and kilograms?
Ask students to estimate their body weight in kilograms. Have them calculate their RMR (also called BMR).
Mention alternative formulas used to calculate RMR.
Have students calculate RMR according to the Mifflin-St. Jeor equation. Is the result similar to that obtained with the formula depicted on the slide?
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18. Factors Influencing Basal Metabolic Rate
Lean body mass (muscles and organs)
Greater metabolic activity in lean tissues
Growth periods
Growth hormone stimulates cell metabolism and raises BMR
Body temperature
Fever increases BMR
Hormonal status
Example: Hypothyroidism = Decreased BMR
Does lean body mass increase or decrease BMR?
Whose BMR most likely will be higher: a 30-year-old man with a high body fat content or a 32-year-old female triathlete?
What percentage of BMR is raised by the growth hormone? 15% to 20%
A patient has a fever of 100° F. How much of an increase in BMR occurs? Fever increases BMR 7% for each 1° F rise in temperature.
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19. Physical Activity
Energy expenditure for physical activity goes above and beyond energy used for resting energy needs.
Energy output during physical activity varies widely across individuals.
Representative kilocalorie expenditures of different types of physical activities are presented in Table 6-2 in the text.
How can a person increase energy expenditure to lose weight? Increase physical activity, build lean muscle mass
What physical activities have high energy expenditure values? Aerobics, cycling, running, fast walking, weight training
Explain that the side effects of emotional stress—muscle tension, restlessness, and agitated movements—might increase energy expenditure, but only slightly.
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20. Energy Expenditure per Pound per Hour
Ask students to calculate kilocalories burned by multiplying their weight in pounds by activity factor by hours.
Which activities would increase their energy output?
Which activities in a nursing student’s daily routine decrease energy output?
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21. Physical Activity Level Factors
Categorize physical activity level (PAL) according to standard values
1.2: Chair or bed bound
: Sedentary
: Very light
: Moderate
: Heavy
Have students calculate their BMR and then multiply by the appropriate PAL factor.
What is the PAL factor for a construction worker who does strenuous work during a 10-hour shift?
What is the PAL factor for a receptionist who sits at a desk for 8 hours and drives to work?
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22. Thermic Effect of Food After eating, food stimulates metabolism
Extra energy for digestion, absorption, and transport is required.
This stimulating effect is called the thermic effect of food (TEF).
5% to 10% of the body’s total energy needs for metabolism relate to the processing of food.
How does the TEF compare to the BMR and physical activity expenditures?
Explain that even though it does take energy to digest, absorb, and transport food, no food produces a negative energy balance. All foods provide energy, including celery and cabbage (two of the more famous foods for weight loss), even if the kilocalories are quite low.
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23. Contributions of RMR, Physical Activity, and TEF on Total Energy Expenditure
Which is the most variable piece of this pie chart?
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24. Total Energy Requirement
Total energy requirement: Resting energy expenditure + Physical activity + TEF
To maintain daily energy balance:
Food energy intake = Body energy output
Intake > output = Weight gain (extreme: obesity)
Intake < output = Weight loss (extreme: anorexia)
To lose weight, what needs to be reduced and what needs to be increased?
If a woman weighs 150 lb (68 kg), eats 2500 kcal/day, and does not exercise, will she gain or lose weight? She will gain weight (energy expenditure = 2307 while kcal intake = 2500).
Explain that the term “anorexia” used here is a clinical term and not the same as anorexia nervosa, the eating disorder.
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25. Life Cycle Growth periods Adulthood
Extra energy per unit of body weight is necessary to build new tissue
Infancy, adolescence, pregnancy
Adulthood
Energy needs level off
With aging, energy needs decline
Do activity levels tend to vary among life stages?
Talk about the extra calories needed during pregnancy and lactation and why this occurs. Ask the class how many more calories, on average, a pregnant woman needs.
Explain why caloric adjustments must be made in the older adult years.
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26. Energy Output in Exercise
Which phase in life has the greatest caloric demand?
Which has the least?
How does gender affect the values?
Figure information:
Copyright PhotoDisc.
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27. Gradual Reduction of Kilocalorie Needs During Adulthood
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28. Dietary Reference Intakes
Food and Nutrition Board of the Institute of Medicine created recommendations for energy intake based on gender, age, and other considerations
See Table 6-5 in text
Ask students to identify where they fit on the Food and Nutrition Board recommendations.
What organ systems are especially affected by an imbalance in energy intake and output?
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29. Dietary Reference Intakes, cont’d
Dietary guidelines for healthy Americans indicate energy needs based on three recommendations:
Maintain body weight in a healthy range
To prevent gradual weight gain over time, make small decreases in food and beverage calories and increase physical activity
Make recommended intakes within energy needs
USDA Food Guide
DASH eating plan
Explain that weight gain is gradual. To combat this increase, small decreases in energy intake must take place.
Review the DASH eating plan and the recommendations from MyPyramid.
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30. Summary Energy is the force or power to do work.
For human beings, food provides energy.
Energy is measured in “large” calories, or kilocalories.
Metabolism is the sum of the body processes involved in converting food into various forms of energy.
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31. Summary, cont’d
When food is not available for energy, stored energy is used in the form of glycogen, fat, and tissue protein.
Total body energy requirements are based on:
Basal metabolism needs measured by BMR
Energy for physical activity
TEF
Energy requirements vary throughout life
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