Chapter 6 Energy Balance

Chapter 6Lesson 6.1

Key ConceptsThe body uses most of its energy intake for basal metabolic work needs.Food energy is changed into body energy and cycled throughout the body to do work.

What is basal metabolism?How is food energy changed into body energy?What happens if there is an imbalance between intake of food and output of work?What diseases can lead to body energy imbalances? What are treatments for these conditions?

Basic Energy NeedsThe body needs constant energy for voluntary and involuntary activityVoluntary work and exerciseIncludes all physical actions related to usual activities and additional physical exercise

(Cont'd)

Is the basal metabolism considered voluntary or involuntary work?If a person is sedentary, how will this affect body energy balance?

Basic Energy Needs(Contd)

Involuntary work: includes all activities of the body that are not consciously performedCirculation, respiration, digestion, other internal activitiesRequirements include:Chemical energy: in many metabolic productsElectrical energy: in brain and nerve activitiesMechanical energy: in muscle contractionThermal energy: to keep the body warm

(Cont'd)

Does voluntary or involuntary work demand the greatest energy requirements?Why?Provide examples of body systems involved in each type of energy.

Basic Energy Needs(Contd)

Fuel is provided in the form of nutrientsThree energy nutrients:Carbohydrate is primary fuelFat assists as storage fuelProtein is a back-up fuel sourceIf sufficient carbohydrate is not consumed to meet energy needs, the body burns fat

To maintain health, average daily food energy intake should equal the daily body energy needs (output).If the body intake is less than the energy output, what nutrient source is burned? (fat)What nutrient do Americans consume too much of?

Measurement of EnergyCalorie: Amount of energy in food or expended in physical actions (common usage)Kilocalorie (1000 calories): Amount of heat necessary to raise 1 kg of water 1 degree Centigrade Large calorie unit used in nutritional science to avoid dealing with large numbersAbbreviation: kcalorie or kcal

Why is kcal the preferred term in nutritional science?What other unit of measurement is sometimes used?How are kcal converted to kilojoules (kJ)? (1 kcal = 4.184 kJ)

Fuel FactorsCarbohydrate: 4 kcal/gFat: 9 kcal/gProtein: 4 kcal/gAlcohol: 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?

Caloric and Nutrient DensityDensity: the degree of concentration of material in a given substanceCaloric density: concentration of energy in a given amount of foodFoods high in fat have the highest caloric densityNutrient density: concentration of all nutrients in a given amount of food

What does the term fuel density refer to?How does it relate to caloric density?Which nutrient has the highest caloric density?What would a nutrient with high vitamin and mineral content be considered?Ask students to consider the nutrient density of the foods they ate at breakfast. Is their diet balanced among the various nutrients?

Chapter 6Lesson 6.2

Key ConceptsA 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.

Energy BalanceTwo energy systems support human lifeExternal energy cycle: plants transform the suns radiation into stored chemical energy; Internal energy cycle: humans eat plant and animal foods

How is energy transformed in the external cycle? (Food chain continues as animals eat plants and other animals.)How is energy transformed in the internal cycle? (Stored energy changes into body fuels, glucose, and fatty acids and cycles them into other energy forms [chemical, electrical, mechanical, thermal].)What are the relationships between the two cycles? (As the internal cycle continues, water is excreted, carbon dioxide is exhaled, and heat is radiated, returning these end products to the environment.)

Energy IntakeThe bodys energy balance depends on energy intake in relation to energy outputEnergy intakeThree energy nutrients in foodEnergy intake is the calculated energy value of actual food consumption

Stored energy is used when food is not available (during sleep or longer fasting periods, for example).Sources of stored energy include glycogen, adipose tissue, and muscle massWhat are the three energy nutrients found in food? (carbohydrates, fats, proteins)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)When is muscle mass used as a food source? (during long periods of fasting or starvation)

Energy OutputActivities to sustain life require energy from food and body reservesThree demands for energy determine the bodys total energy requirements Resting energy expenditure (REE)Physical activityThermic effect of food

Chemical changes occurring during these activities are called metabolism.Exchange of energy in overall balance is usually expressed in kcals.All internal working activities are referred to as what? (basal energy expenditure [BEE])Of the three demands for energy, which requires the most energy? (Resting energy expenditure liver, brain, heart, kidneys, and GI tractaccount for 60% to 75% of basal metabolic needs.)

Resting Energy Expenditure (REE)Sum of all internal working activities of the body at restExpressed as kcal/dayBasal 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 in order 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 GI tract) How does this requirement compare to their overall total body weight? (These organs amount to less than 5% of body weight.)

Measurement of Resting Metabolic RateHow can resting or basal metabolic rate be measured?Indirect calorimetryMetabolic rate calculated based on the rate of oxygen utilizationThyroid function testMeasures the activity of the thyroid gland and the blood levels of the hormone thyroxine

(Cont'd)

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 mouthpiece or ventilated hood system while lying in bed.)What does the thyroid gland help regulate? (The thyroid hormone regulates metabolism.)How is iodine related to thyroxine? (Iodine is an important part of the hormone thyroxine; unusually high or low intakes of iodine are associated with thyroid disease.)

Measurement of Resting Metabolic Rate(Contd)

General formulaMen1 kcal x kg body weight x 24 hoursWomen0.9 kcal x kg body weight x 24 hours

What is the conversion factor for pounds and kilograms? (1 kg = 2.2 lbs.)Ask students to estimate their body weight in kilograms.Have students then calculate their RMR (also called BMR).What is an alternative formula for calculating BMR? (Harris-Benedict equations)Ask students to use the Harris-Benedict equation to calculate their BMR. Is it the result similar to the result obtained with the formula depicted on the slide?

Factors Influencing Basal Metabolic RateLean 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 BMRHormonal statusEx. Hypothyroidism = decreased BMR

How does lean body mass affect BMR? (BMR is higher in lean bodies, thus requiring more energy.)Whose BMR most likely will be higher: a 30-year-old male with a high body fat content or a 32-year-old female triathlete? (female triathlete)What percentage of BMR is raised by the growth hormone? (15% to 20%)What additional energy requirements in kcal are needed during pregnancy? (additional 300 kcal/day, on average)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.)

Physical ActivityEnergy expenditure for physical activity goes above and beyond energy used for resting energy needsEnergy output during physical activity varies widely across individuals

Representative kcal 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)What physical activities have high energy expenditure values? (aerobics, cycling, running, fast walking, weight training)Does studying for nursing examinations require large amounts of energy? (no)What side effects of emotional stress might increase energy expenditure slightly? (muscle tension, restlessness, agitated movements)

Energy Expenditure per Pound per Hour

Ask students to calculate kcal burned by multiplying their weight in pounds by activity factor by hours.Which activities would increase their energy output? Which activities in a nursing students daily routine decrease energy output?

PAL FactorsCategorize physical activity level (PAL) according to standard values (1.2 to 2.4, depending on lifestyle) and then multiplying by resting metabolic rate

What is the physical activity level (PAL) factor? 1.2: chair or bed-bound1.4-1.5: sedentary1.6-1.7: very light1.8-1.9: moderate2.0-2.4: heavyCalculate your BMR and then multiply by 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 eight hours and drives to work?

Thermic Effect of FoodAfter eating, food stimulates metabolismExtra energy for digestion, absorption, and transport is required.This stimulating effect is called the thermic effect of food (TEF).5%-10% of the bodys total energy needs for metabolism relates to the processing of food

How does the thermic effect of food compare to the BMR and physical activity expenditures?How can the thermic effect of food intake be calculated?

Total Energy RequirementTotal energy requirement: resting energy expenditure + physical activity + thermic effect of foodTo maintain daily energy balance:Food-energy intake = body-energy outputIntake > output = weight gain (extreme: obesity)Intake < output = weight loss (extreme: anorexia)

In order to lose weight, what needs to be reduced and what needs to be increased?If a woman weighs 150 lbs. (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.])

Total Energy Expenditure

Which energy requirement has the greatest demand? (resting metabolic rate)Which has the least?

Life CycleGrowth periodsExtra energy per unit of body weight is necessary to build new tissueInfancy, adolescence, pregnancyAdulthoodEnergy needs level offWith aging, energy needs decline

Do activity levels tend to vary among life stages? What effect does this have along with BMR variations?What caloric adjustments need to occur during growth periods?During advancing age?How many more calories should be consumed during pregnancy or lactation?

Caloric Allowances (Birth to 18)

Which phase in life has the greatest caloric demand?Which has the least?How does gender affect the values?

Gradual Reduction of Kcal Needs

What percentage of reduction in kcal should occur during adulthood?How can considering caloric density and nutrient density when planning meals help maintain an energy balance throughout life?What activities are recommended forms of exercise for older adults?How does weightlifting influence energy balance?

Dietary Reference IntakesFood 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)

(Cont'd)

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?

Dietary Reference Intakes(Contd)

Dietary Guidelines for healthy Americans indicate energy needs based on two recommendations:Maintain a healthy weightChoose a diet low in fat, saturated fat, and cholesterol; use sugars in moderation; eat plenty of fruits, vegetables, and grain products

Does the typical American diet follow the dietary guidelines?How does fast food relate to these guidelines?

What is basal metabolism?How is food energy changed into body energy?What happens if there is an imbalance between intake of food and output of work?What diseases can lead to body energy imbalances? What are treatments for these conditions?Is the basal metabolism considered voluntary or involuntary work?If a person is sedentary, how will this affect body energy balance?Does voluntary or involuntary work demand the greatest energy requirements?Why?Provide examples of body systems involved in each type of energy.To maintain health, average daily food energy intake should equal the daily body energy needs (output).If the body intake is less than the energy output, what nutrient source is burned? (fat)What nutrient do Americans consume too much of?Why is kcal the preferred term in nutritional science?What other unit of measurement is sometimes used?How are kcal converted to kilojoules (kJ)? (1 kcal = 4.184 kJ)What is the caloric value of 5 g of carbohydrate?10 g of fat?30 g of protein?40 g of alcohol?What does the term fuel density refer to?How does it relate to caloric density?Which nutrient has the highest caloric density?What would a nutrient with high vitamin and mineral content be considered?Ask students to consider the nutrient density of the foods they ate at breakfast. Is their diet balanced among the various nutrients?

How is energy transformed in the external cycle? (Food chain continues as animals eat plants and other animals.)How is energy transformed in the internal cycle? (Stored energy changes into body fuels, glucose, and fatty acids and cycles them into other energy forms [chemical, electrical, mechanical, thermal].)What are the relationships between the two cycles? (As the internal cycle continues, water is excreted, carbon dioxide is exhaled, and heat is radiated, returning these end products to the environment.)Stored energy is used when food is not available (during sleep or longer fasting periods, for example).Sources of stored energy include glycogen, adipose tissue, and muscle massWhat are the three energy nutrients found in food? (carbohydrates, fats, proteins)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)When is muscle mass used as a food source? (during long periods of fasting or starvation)Chemical changes occurring during these activities are called metabolism.Exchange of energy in overall balance is usually expressed in kcals.All internal working activities are referred to as what? (basal energy expenditure [BEE])Of the three demands for energy, which requires the most energy? (Resting energy expenditure liver, brain, heart, kidneys, and GI tractaccount for 60% to 75% of basal metabolic needs.)An individual with an REE of 1500 kcal/day would need to consume that amount of energy over a 24-hour period in order 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 GI tract) How does this requirement compare to their overall total body weight? (These organs amount to less than 5% of body weight.)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 mouthpiece or ventilated hood system while lying in bed.)What does the thyroid gland help regulate? (The thyroid hormone regulates metabolism.)How is iodine related to thyroxine? (Iodine is an important part of the hormone thyroxine; unusually high or low intakes of iodine are associated with thyroid disease.)What is the conversion factor for pounds and kilograms? (1 kg = 2.2 lbs.)Ask students to estimate their body weight in kilograms.Have students then calculate their RMR (also called BMR).What is an alternative formula for calculating BMR? (Harris-Benedict equations)Ask students to use the Harris-Benedict equation to calculate their BMR. Is it the result similar to the result obtained with the formula depicted on the slide?How does lean body mass affect BMR? (BMR is higher in lean bodies, thus requiring more energy.)Whose BMR most likely will be higher: a 30-year-old male with a high body fat content or a 32-year-old female triathlete? (female triathlete)What percentage of BMR is raised by the growth hormone? (15% to 20%)What additional energy requirements in kcal are needed during pregnancy? (additional 300 kcal/day, on average)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.)Representative kcal 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)What physical activities have high energy expenditure values? (aerobics, cycling, running, fast walking, weight training)Does studying for nursing examinations require large amounts of energy? (no)What side effects of emotional stress might increase energy expenditure slightly? (muscle tension, restlessness, agitated movements)Ask students to calculate kcal burned by multiplying their weight in pounds by activity factor by hours.Which activities would increase their energy output? Which activities in a nursing students daily routine decrease energy output?What is the physical activity level (PAL) factor? 1.2: chair or bed-bound1.4-1.5: sedentary1.6-1.7: very light1.8-1.9: moderate2.0-2.4: heavyCalculate your BMR and then multiply by 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 eight hours and drives to work?How does the thermic effect of food compare to the BMR and physical activity expenditures?How can the thermic effect of food intake be calculated?In order to lose weight, what needs to be reduced and what needs to be increased?If a woman weighs 150 lbs. (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.])Which energy requirement has the greatest demand? (resting metabolic rate)Which has the least?Do activity levels tend to vary among life stages? What effect does this have along with BMR variations?What caloric adjustments need to occur during growth periods?During advancing age?How many more calories should be consumed during pregnancy or lactation?Which phase in life has the greatest caloric demand?Which has the least?How does gender affect the values?What percentage of reduction in kcal should occur during adulthood?How can considering caloric density and nutrient density when planning meals help maintain an energy balance throughout life?What activities are recommended forms of exercise for older adults?How does weightlifting influence energy balance?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?Does the typical American diet follow the dietary guidelines?How does fast food relate to these guidelines?