chapter 006

Williams' Basic Nutrition & Diet Therapy

Chapter 6

Energy Balance

Copyright © 2013 Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 1

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.

2Copyright © 2013 Mosby, Inc., an imprint of Elsevier Inc. All rights reserved.

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


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


Sources of Fuel (p. 81)

Provided in the form of ATP Carbohydrate: primary source of fuel Fat Protein


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


Food Energy: Fuel Factors(p. 82)

Carbohydrate: 4 kcal/g Fat: 9 kcal/g Protein: 4 kcal/g Alcohol: 7 kcal/g


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


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.


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


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


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


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


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


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)


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.


Case Study (cont’d)

How many calories does Sarah need to consume each day to maintain her current weight?



What is the difference between REE and BEE?



Which organ systems use much of the body energy for cellular function?


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


Energy Output (cont’d) (p. 83)


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


Case Study

Calculate YOUR resting metabolic rate.


Case Study

Calculate YOUR RMR according to the Mifflin-St. Jeor equation. What is the result?


Predicting Basal Metabolic Rate (cont’d) (p. 84)

Thyroid function tests also can be used Thyroid hormone regulates metabolism


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


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)


Thermic Effect of Food (p. 88)

Digestion Absorption Transportation of nutrients to cells


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)


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)


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


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)


Dietary Reference Intakes (p. 90)

Use Table 6-4 Note average weight, height, BMI, and PAL for each

group


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


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


http://www.choosemyplate.gov/

chapter 006

Technology

body energy

energy systems

basic energy

energy supply

measurement of energy

energy balance copyright

intake of food energy

fat energy intake