Chapters8

Chapters8 & 9 Energy Balance, Body Composition and Weight

Management

Learning Objectives

• Explain various internal and external forces that regulate satiety, hunger, and appetite.

• Define basal metabolism and the factors that alter basal metabolism.

• Explain thermic effect and physical activit6y as part of overall energy usage.

• Explain direct and indirect calorimetry.

Learning Objectives cont.

• Calculate and interpret body mass index.

• Explain health risks of obesity and describe role of waist-to-hip ratio in risk assessment.

• Define types of obesity and treatment implications.

• Discuss nature and nurture in obesity development.

Learning Objectives cont.

• Determine if a weight loss program is sound or fad.

• Outline behavior modification for weight control.

• Discuss role of diet and physical activity for weight loss.

• Discuss effectiveness of medical interventions in obesity treatment.

Learning Objectives

• Define underweight and describe guidelines for management of underweight.

• Discuss the reasons weight loss is difficult to accomplish and maintain.

• Discuss the possibilities of programs for overweight/obesity prevention.

• Assess the attitude of yourself and society toward the overweight and obese.

Learning objectives – cont.

• Define common types of eating disorders, describe how they develop and explain impact on victim.

• Describe treatments used on eating disorders.

• Identify diagnostic criteria for eating disorders.

Energy Balance• “State in which energy intake, in the form of food and

/or alcohol, matches the energy expended, primarily through basal metabolism and physical activity”

• Positive energy balance– Energy intake > energy expended

– Results in weight gain

• Negative energy balance– Energy intake < energy expended

– Results in weight loss

Energy Balance (Fig. 13-1)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Energy In Vs. Energy Out

Basal Metabolism

Dietary Intake Physical Activity

Thermic Effect of food

Basal Metabolism

• The minimum energy expended to keep a resting, awake body alive

• ~60-70% of the total energy needs

• Includes energy needed for maintaining a heartbeat, respiration, body temperature

• Amount of energy needed varies between individuals

Influences On Basal Metabolism• Body surface area (weight, height)• Gender• Body temperature• Thyroid hormone• Age• Kcal intake• Pregnancy• Use of caffeine and tobacco

Physical Activity

• Increases energy expenditure beyond BMR

• Varies widely among individuals

• More activity, more energy burned

• Lack of activity is the major cause of obesity

Thermic Effect of Food (TEF)

• Energy used to digest, absorb, and metabolize food nutrients

• ~5-10% above the total energy consumed

• TEF is higher for CHO and protein than fat

• Less energy is used to transfer dietary fat into adipose stores

• Suggesting what?

Measurement of Body’s Energy Needs

• Direct calorimetry– Measures heat output from the body using an

insulated chamber– Expensive and complex

• Indirect calorimetry– Measures the amount of oxygen a person uses– A relationship exists between the body’s use of

energy and oxygen

Harris-Benedict Equation

• Estimates resting energy needs

• Considers height, weight, age, and gender

• For men: 66.5 + 13.8x(kg) + 5x(cm) - 6.8x(age in yr.)

• For women:

655.1 + 9.6x(kg) + 1.8x(cm) - 4.7x(age in yr.)

Sample Calculations

• Man: 21 yr., 5’10” (171 cm), 155# (70 kg)

66.5 + 13.8x(70kg) + 5x(171cm) - 6.8x(21) = 1745 kcal/day

• Woman: 21 yr., 5’10” (171 cm), 155# (70kg)

655.1 + 9.6x(70kg) + 1.8x(171cm) - 4.7x(21)= 1536 kcal/day

Why Do You Eat?

• Hunger– Physiological (internal) drive to eat– Controlled by internal body

• Appetite– Psychological (external) drive to eat– Often in the absence of hunger– e.g., seeing/smelling fresh baked chocolate chip

cookies

Satiety Regulator• The hypothalamus

– When feeding cells are stimulated, they signal you to eat

– When satiety cells are stimulated, they signal you to stop eating

• Sympathetic nervous system– When activity increases, it signals you to stop

eating– When activity decreases, it signals you to eat

Why We Eat

• Appetite is affected by a variety of external forces

• Combination of internal and external signals drive us to eat

• Not a perfect system; desire to eat can be overwhelming

What is a Healthy Body Weight?

• Based on how you feel, weight history, fat distribution, family history of obesity-related disease, current health status, and lifestyle

• Current height/weight standards only provide guides

Body Mass Index (BMI)

• The preferred weight-for-height standard

• Calculation:

Body wt (in kg) OR Body wt (in lbs) x 703.1

[Ht (in m)]2 [Ht (in inches)]2

Health risks increase when BMI is > 25

Estimation of Healthy WeightFor men:

106 pounds for the first 5 feet

add 6 pounds per each inch over five feet

A man who is 5’10” should weigh 166 lbs.

For women:

100 pounds for the first 5 feet

add 5 pounds per each inch over five feet

A women who is 5’10” should weigh 150 lbs.

Obesity

• Excessive amount of body fat– Women with > 30-35% body fat– Men with > 25% body fat

• Increased risk for health problems

• Are usually overweight

• Measurements using calipers

Estimation of Body Fat

• Underwater weighing (Fig. 13-5)– Most accurate

– Fat is less dense than lean tissue

– Fat floats


Estimation of Body Fat• Bioelectrical impedance

– Low-energy current to the body that measures the resistance of electrical flow

– Fat is resistant to electrical flow; the more the resistance, the more body fat you have

• X-ray photon absorptiometry– An X-ray body scan that allows for the determination of

body fat

• Infrared light– Assess the interaction of fat and protein in the arm muscle


Body Fat DistributionUpper-body (android) obesity--”Apple shape”• Associated with more heart disease, HTN, Type II

Diabetes• Abdominal fat is released right into the liver• Fat affects liver’s ability to clear insulin and lipoprotein• Encouraged by testosterone and excessive alcohol

intake• Defined as waist to hip ratio of >1.0 in men and >0.8 in

women

Body Fat Distribution (Fig.13-9)


Body Fat Distribution

Lower-body (gynecoid) obesity--”Pear shape”

• Encouraged by estrogen and progesterone

• After menopause, upper-body obesity appears

• Less health risk than upper-body obesity

Overweight and Obesity

• Underweight = BMI < 18.5

• Healthy weight = BMI 18.5-24.9

• Overweight = BMI 25-29.9

• Obese = BMI 30-39.9

• Severely obese = BMI >40

Juvenile-Onset Obesity

• Develops in infancy or childhood

• Increase in the number of adipose cells

• Adipose cells have long life span and need to store fat

• Makes it difficult to loose the fat (weight loss)

Adult-Onset Obesity

• Develops in adulthood

• Fewer (number of) adipose cells

• These adipose cells are larger (stores excess amount of fat)

• If weight gain continues, the number of adipose cells can increase

Causes of ObesityNature debate

• Identical twins raised apart have similar weights

• Genetics account for ~40% of weight differences

• Genes affect metabolic rate, fuel use, brain chemistry

• Thrifty metabolism gene allows for more fat storage to protect against famine

Causes of Obesity

Nurture debate

• Environmental factors influence weight

• Learned eating habits

• Activity factor (or lack of)

• Poverty and obesity

• Female obesity is rooted in childhood obesity

• Male obesity appears after age 30

Nature and Nurture• Obesity is nurture allowing nature to express

itself

• Location of fat is influenced by genetics

• A child with no obese parents has a 10% chance of becoming obese

• A child with 1 obese parent has a 40% chance

• A child with 2 obese parents has a 80% chance

Nature Vs. Nurture

• Those at risk for obesity will face a lifelong struggle with weight

• Gene does not control destiny

• Increased physical activity, moderate intake can promote healthy weight

Set Point Theory

• Weight is closely regulated by the body

• Genetically predetermined body weight

• Body resists weight change

• Leptin assists in weight regulation

• Weight returns after weight loss

• Reduction in energy intake results in lower metabolic rate

• Ability to shift the set point weight

Why Diets Don’t Work

• Obesity is a chronic disease– Treatment requires long-term lifestyle changes

• Dieters are misdirected– More concerned about weight loss than healthy

lifestyle– Unrealistic weight expectations


Body defends itself against weight loss

• Thyroid hormone concentrations (BMR) drop during weight loss and make it more difficult to lose weight

• Activity of lipoprotein lipase increases making it more efficient at taking up fat for storage


Weight cycling (yo-yo dieting)

• Typically weight loss is not maintained

• Weight lost consists of fat and lean tissue

• Weight gained after weight loss is primarily adipose tissue

• Weight gained is usually more than weight lost

• Associated with upper body fat deposition

Why Diets Don’t WorkWeight gain in adulthood• Weight gain is common from ages 25-44• BMR decreases with age• Inactive lifestyle

Changes in body composition • Fluid is usually the first weight lost• Loss in lean body tissue means lowering the BMR• Very little fat is lost during weight loss

Lifestyle Vs. Weight Loss

• Prevention of obesity is easier than curing

• Balance energy in(take) with energy out(put)

• Focus on improving food habits

• Focus on increase physical activities

What It Takes To Lose a Pound

• Body fat contains 3500 kcal per pound

• Fat storage (body fat plus supporting lean tissues) contains 2700 kcal per pound

• Must have an energy deficit of 2700-3500 kcal to lose a pound per week

Do the MathTo lose one pound, you must create a deficit of 2700-3500 kcal

So to lose a pound in 1 week (7 days), try cutting back on your kcal intake and increase physical activity so that you create a deficit of 400-500 kcal per day

- 500 kcal x 7 days = - 3500 kcal = 1 pound of weight loss

day week in 1 week

Sound Weight Loss Program• Meets nutritional needs, except for kcal• Slow & steady weight loss • Adapted to individuals’ habits and tastes• Contains enough kcal to minimize hunger and

fatigue• Contains common foods• Fit into any social situation• Chang eating problems/habits• Improves overall health• See a physician before starting

Cutting Back

• Control calorie intake by being aware of kcal and fat content of foods

• “Fat Free” does not mean “Calories Free” (or “All You Can Eat”)

• Read food labels

• Estimate kcal using the exchange system

• Keep a food diary

Regular Physical Activity

• Fat use is enhanced with regular physical activity

• Increases energy expenditure

• Duration and regularity are important

• Make it a part of a daily routine

Behavior Modification

• Modify problem (eating) behaviors

• Chain-breaking

• Stimulus control

• Cognitive restructuring

• Contingency management

• Self-monitoring

Weight Maintenance• Prevent relapse

– Occasional lapse is fine, but take charge immediately

– Continue to practice newly learned behavior– Requires “motivation, movement, and monitoring”

• Have social support– Encouragement from friends/ family/ professionals

Dieting Can Be Hazardous To Your Health

• Weight regained consists of a higher percentage of body fat than before

• Less healthy than before dieting

• Weight loss diet should not be considered unless you are committed and motivated

Diet Drugs

• Amphetamine (Phenteramine)– Prolongs the activity of epinephrine and

norepinephrine in the brain– Decreases appetite– Not recommended for long term use

• Sibutramine (Meridia)– Enhances norepinephrine and serotonin activity– Decreases appetite(eat less)– Not recommended for people with HTN

Diet DrugsOrlistat (Xenical)• Inhibits fat digestion• Reduces absorption of fat in the small intestine• Fat is deposited in the feces with its side effects• Must control fat intake• Malabsorption of fat-soluble vitamins• Supplements needed

Homeopathic drug

• Ephedrine (ma huang)– Linked to illnesses and death– Associated with nervous and cardiovascular

disorder

• St. John’s Wort– Antidepressant

• Both taking together– Not recommended until careful testing is done

Over-The-Counter Diet Aids

• Phenylpropanolamine – recently banned– Epinephrine-like drug– Cause a slight decrease in food intake

• Fiber– “Filler” leading to satiety– Causes stomach distention

• Benzocaine– Numbs the tongue and taste buds

Gastroplasty - Stomach Stapling• Common surgical procedure for treating severe

obesity

• Reduces the stomach size (from 4 cups) to half a shot glass size (1 oz)

• Overeating will result in rapid vomiting

• Smaller stomach promotes satiety earlier

• 75% will lose ~50% of excess body weight

• Costly

• Dumping syndrome

Gastroplasty (Fig. 13-13)


Underweight is Also a Problem

• 15-25% below healthy weight or BMI of <18.5

• Associated with increased deaths, menstrual dysfunction, pregnancy complications, slow recovery from illness/surgery

• Causes are the same as for obesity but in the opposite route

Treatment for Underweight

• Intake of energy-dense foods (energy input)

• Encourage meals and snacks

• Reduce activity (energy output)

• To gain a pound you need a total excess intake of 2700-3500 kcal

Eating Disorders

• Anorexia

• Bulemia

• Baryophobia

• Female Athlete Triad

Chapters8

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Transcript of Chapters8