Download - Chapter 006
Williams' Basic Nutrition & Diet Therapy
Chapter 6
Energy Balance
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14th Edition
Lesson 6.1: Food Energy, Body Energy, and Basal Metabolism
Food energy is changed into body energy to do work. The body uses most of its energy supply for basal
metabolic needs.
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Human Energy System (p. 81)
Basic energy needs Voluntary work: conscious activities of daily living Involuntary body work: greatest share of energy
output• Circulation• Respiration• Digestion• Absorption
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Human Energy System (cont’d) (p. 81)
Involuntary body work (cont’d) Chemical energy: many metabolic processes Electrical energy: brain and nerve activities Mechanical energy: muscle contraction Thermal energy: to maintain body temperature
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Sources of Fuel (p. 81)
Provided in the form of ATP Carbohydrate: primary source of fuel Fat Protein
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Measurement of Energy (p. 81)
Calorie is the term in common usage Kilocalorie (1000 calories) is used in nutrition
science Amount of heat needed to raise 1 kg of water 1° C Abbreviated as kcalorie or kcal
Joule (J): international unit Convert kcal to kJ: multiply kcal by 4.184
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Food Energy: Fuel Factors(p. 82)
Carbohydrate: 4 kcal/g Fat: 9 kcal/g Protein: 4 kcal/g Alcohol: 7 kcal/g
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Caloric and Nutrient Density(p. 82)
Density: degree of concentration of material in a given substance
Caloric density: high concentration of energy in a small amount of food
Fats have highest caloric density Nutrient density: relative concentration of nutrients
(e.g., vitamins and minerals) Food guides recommend foods that are nutrient-
dense
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Lesson 6.2: Balancing Intake and Output; Effects of Imbalance
3. A balance between intake of food energy and output of body work maintains life and health.
4. States of being underweight and overweight reflect degrees of energy imbalance.
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Energy Balance (p. 82)
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
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Energy Intake (p. 82)
Energy intake The body’s energy balance depends on energy
intake in relation to energy output Main source of energy is food, supplemented by
energy stored in body tissues
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Sources of Food Energy (p. 82)
Sources of food energy Carbohydrates, protein, and fat Energy intake can be computed by tracking intake
and calculating its energy value Nutritrac on Evolve is an excellent tool for
calculating energy intake ChooseMyPlate is another free software tool for
calculating energy intake
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Sources of Stored Energy (p. 82)
Sources of stored energy Glycogen: 12- to 48-hour store in liver and
muscles Adipose tissue: varies by individual, most
concentrated form of energy Muscle mass: used only during longer periods of
fasting or starvation
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Energy Output (p. 83)
Metabolism: chemical changes that occur during: Normal body functions Regulation of body temperature Tissue growth and repair
Total energy demands determined by: Resting energy expenditure Physical activity Thermic effect of food
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Resting Energy Expenditure(p. 83)
Sum of all working internal activities of the body Expressed in kilocalories per day Also called resting metabolic rate (RMR), basal
energy expenditure (BEE)
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Case Study
Sara, a 35-year-old female, has a REE of 1500 kcal/d. She works 6-8 hours a day and usually takes a 2-mile walk after work.
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Case Study (cont’d)
How many calories does Sarah need to consume each day to maintain her current weight?
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Case Study (cont’d)
What is the difference between REE and BEE?
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Case Study (cont’d)
Which organ systems use much of the body energy for cellular function?
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Energy Output (p. 83)
Measuring basal metabolic rate or resting metabolic rate Sometimes done in clinical practice Uses indirect calorimetry Measures exchange of carbon dioxide
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Energy Output (cont’d) (p. 83)
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Predicting Basal Metabolic Rate (p. 84)
Multiply 0.9 or 1 kcal/kg body weight by 24 (hours in a day)
Other measures are available Mifflin-St. Jeor equation found to give most reliable
RMR
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Case Study
Calculate YOUR resting metabolic rate.
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Case Study
Calculate YOUR RMR according to the Mifflin-St. Jeor equation. What is the result?
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Predicting Basal Metabolic Rate (cont’d) (p. 84)
Thyroid function tests also can be used Thyroid hormone regulates metabolism
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Factors That Influence Basal Metabolic Rate (p. 84)
Lean body mass: 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
decreases BMR
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Physical Activity (p. 86)
Exercise reduces risk of many diseases, improves quality of life
Energy expenditure can be estimated by categorizing activity and multiplying RMR by category factor (1.0 to 2.5)
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Thermic Effect of Food (p. 88)
Digestion Absorption Transportation of nutrients to cells
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Total Energy Requirement (p. 88)
Total energy requirement made up of: RMR + 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)
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Total Energy Requirement (cont’d) (p. 89)
Use Clinical Applications box, “Evaluate Your Daily Energy Requirements”
Record food and activities for a day Calculate energy intake (kilocalories) and output
(kilocalorie expenditure)
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Recommendations for Dietary Energy Intake (p. 90)
General life cycle Growth periods
• Extra energy needed to build new tissues• Greatest growth is infancy through adolescence• Pregnancy and lactation also require increased energy
intake
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General Life Cycle (p. 90)
Adulthood Energy needs plateau as full growth achieved BMR then declines 1% to 2% per decade,
reducing energy needs Rapid decline occurs at age 40 (men) and 50
(women)
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Dietary Reference Intakes (p. 90)
Use Table 6-4 Note average weight, height, BMI, and PAL for each
group
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Dietary Guidelines for Americans (p. 91)
Prevent/reduce overweight/obesity through improved eating and physical activity
Control calorie intake to manage body weight Increase physical activity and reduce sedentary
activities Adjust calorie balance to stage of life Select eating pattern that meets nutrient needs over
time
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Choose MyPlate (p. 91)
Web site: www.choosemyplate.gov Determine calorie level and serving sizes from each
good group Based on age, gender, weight, height, activity level
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