unit 13 weight control

8/2/2019 Unit 13 Weight Control

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ENERGY BALANCE AND

WEIGHT CONTROL


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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


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ENERGY BALANCE


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ESTIMATING KCAL

CONTENT IN FOOD Bomb calorimeter

Burns food inside a

chamber surrounded

by water Heat is given off as

food is burned

The increase in water

temperature indicates

the amount of energy

in the food


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MACRONUTRIENTS AND FAT

STORAGE Most fat is stored directly into adipose

tissue

Body has unlimited ability to store fat (as

fat)

Limited CHO can be stored as glycogen

Most CHO is used as a energy source

Excessive CHO will be converted into fat

(for storage)


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Macronutrients and Fat Storage

Protein is primarily used for tissue synthesis

Adults generally consume more protein than

needed for tissue synthesis

Some protein will be converted into fat (for

storage)


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MACRONUTRIENTS AND FAT

STORAGE Body prefers to use CHO as energy source

Only excess intake of CHO and protein will

be turned into fat

Fat will remain as fat for storage

Physical activity encourages the burning of

dietary fat


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ENERGY IN vs ENERGY OUT

Basal Metabolism

Dietary Intake Physical Activity

Thermic Effect of food


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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


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INFLUENCES ON BASAL

METABOLISM Body surface area (weight, height)

Gender

Body temperature Thyroid hormone

Age

Kcal intake

Pregnancy

Use of caffeine and tobacco


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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


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THERMIC EFFECT OF FOOD

Energy used to digest, absorb, and

metabolize food nutrients

Sales tax of total energy consumed ~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


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NONEXERCISE ACTIVITY

THERMOGENESIS Nonvoluntary physical activity triggered by

overeating

Fidgeting

Over eating increases sympathetic nervous

system activity

Resists weight gain


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MEASUREMENT OF

BODYS 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 bodys use of

energy and oxygen


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HARRIS-BENEDICT EQUATION

FOR THE BODYS ENERGY

NEEDS

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.)


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SAMPLE CALCULATIONS

Man: 21 yr., 510 (171 cm), 155# (70 kg)

66.5 + 13.8x(70kg) + 5x(171cm) - 6.8x(21)

= 1745 kcal/day

Woman: 21 yr., 510 (171 cm), 155# (70kg)

655.1 + 9.6x(70kg) + 1.8x(171cm) -

4.7x(21)= 1536 kcal/day


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ESTIMATED ENERGY

REQUIREMENT (EER) FOR MEN

EER =662 - (9.53 x AGE) + PA x (15.91 x

WEIGHT + 539.6 x HEIGHT )

FOR WOMEN

EER = 354(6.91 x AGE) + PA x (9.36 x

WEIGHT + 726 x HEIGHT)


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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


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WHY WE EAT

Appetite is affected by a variety of external

forces

Combination of internal and external signalsdrive us to eat

Not a perfect system; desire to eat can be

overwhelming


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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


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Influences of Satiety


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Influences of Satiety


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WHAT IS A HEALTHY BODY

WEIGHT? Based on how you feel, weight history, fat

distribution, family history of obesity-

related disease, current health status, andlifestyle

Current height/weight standards only

provide guides


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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


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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 510 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 510 should weigh 150 lbs.


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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


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ESTIMATION OF BODY FAT

Underwater weighing(Fig. 13-5)

Most accurate

Fat is less dense than

lean tissue Fat floats


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ESTIMATION OF BODY FAT

Bioelectrical impedanceLow-energy current to the body that measures

the resistance of electrical flow

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

X-ray photon absorptiometry

An X-ray body scan that allows for thedetermination of body fat

Infrared light

Assess the interaction of fat and protein in the

arm muscle


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BODY FAT DISTRIBUTION

Upper-body (android) obesity--Apple shape

Associated with more heart disease, HTN,

Type II Diabetes

Abdominal fat is released right into the liver

Fat affects livers 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


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Lower-body (gynecoid) obesity--Pear shape

Encouraged by estrogen and progesterone

After menopause, upper-body obesity

appears

Less health risk than upper-body obesity


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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


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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)


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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


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CAUSES OF OBESITY

Nature debate

Identical twins raised apart have similar

weights Genetics account for ~40% of weight

differences

Genes affect metabolic rate, fuel use, brainchemistry

Thrifty metabolism gene allows for more fat

storage to protect against famine


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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


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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


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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


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WHY DIETS DONT 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


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WHY DIETS DONT WORK

Body defends itself against weight loss

Thyroid hormone concentrations (BMR)

drop during weight loss and make it moredifficult to lose weight

Activity of lipoprotein lipase increases

making it more efficient at taking up fat forstorage


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WHY DIETS DONT WORK

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


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WHY DIETS DONT 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


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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


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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


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DO THE MATH

To 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 youcreate 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


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SOUND WEIGHT LOSS

PROGRAM

Slow & steady weight loss

Adapted to individuals habits and tastes

Contains enough kcal to minimize hunger andfatigue

Contains common foods

Fit into any social situation See a physician before starting


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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


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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


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BEHAVIOR MODIFICATION

Modify problem (eating) behaviors

Chain-breaking

Stimulus control

Cognitive restructuring

Contingency management

Self-monitoring


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CHAIN-BREAKING

Breaking the link between two behaviors

These links can lead to excessive intake

Snacking while watching T.V.


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STIMULUS CONTROL

Alternating the environment to minimize

the stimuli for eating

Puts you in charge of temptations


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COGNITIVE RESTRUCTURING

Changing your frame of mind regarding

eating

Replace eating due to stress with walking


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CONTINGENCY

MANAGEMENT Forming a plan of action in response to a

situation

Rehearse in advance appropriate responsesto pressure of eating at parties


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SELF-MONITORING

Tracking foods eaten and conditions

affecting eating

Helps you understand your eating habits


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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 supportEncouragement from friends/ family/

professionals

DIETING CAN BE


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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


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Diet Drugs

Amphetamine (Phenteramine)

Prolongs the activity of epinephrine and

norepinephrine in the brainDecreases appetite

Not recommended for long term use

Sibutramine (Meridia)Enhances norepinephrine and serotonin activity

Decreases appetite(eat less)

Not recommended for people with HTN

GASTROPLASTY STOMACH


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GASTROPLASTY - STOMACH

STAPLING

Common surgical procedure for treatingsevere 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


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GASTROPLASTY


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UNDERWEIGHT IS ALSO A

PROBLEM 15-25% below healthy weight or BMI of


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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

unit 13 weight control

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