Chapter 9
Weight
Management
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Ask Yourself
1.
2.
3.
4.
5.
The less you weigh, the better it is for your health.
Obese people pay higher insurance premiums than
thin people.
If you weigh too much according to the scales and the
so-called ideal weight tables, you are too fat.
If you are too fat, it is because you eat too much.
Basal metabolism contributes only a small percentage
of a person’s daily energy output.
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Ask Yourself
6.
Probably the most important contributor to the
obesity problem in our country is under activity.
7. Any food can make you fat, even carrot sticks, if you
eat enough of it.
8. You can lose weight faster on a properly designed diet
and exercise program than on a total fast.
9. Fad diets are popular because their followers achieve
quick and permanent weight loss.
10. Anorexia nervosa is a disease in which a person has
no appetite.
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A Closer Look at Obesity
Bodies come in many shapes and sizes.
Which are healthy?
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A Closer Look at Obesity
Trends in Prevalence of Overweight and Obesity among Children
and Adults, United States, 1988–2004
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A Closer Look at Obesity
• Many factors including genetics
influence body weight.
• Excess energy intake and physical
inactivity are the leading causes of
overweight and obesity.
They also represent the best
opportunities for prevention and
treatment.
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A Closer Look at Obesity
Trends resulting in poor nutrition and decreased activity:
• Food portion sizes and obesity rates have grown in parallel.
• Vending machines selling soft drinks, high-fat snacks, and sweet
snacks are common in schools and workplaces.
• Adults spend more time in sedentary activities, such as watching
television, computing, or commuting.
• Children watch 12 to 14 hours of television a week and spend 7
hours playing video games.
• Schools offer fewer physical education classes for children.
• Increasing numbers of families live in communities designed for car
use, unsuitable and often unsafe for activities such as walking,
biking, and running.
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A Closer Look at Obesity
• Overweight:
conventionally defined as
weight between 10% and
20% above the desirable
weight for height, or a
body mass index (BMI) of
25.0 through 29.9.
• Obesity: conventionally
defined as weight 20% or
more above the desirable
weight for height, or a
BMI of 30 or greater.
Fact:
• Obesity rates are higher
than ever.
 Currently, 67% of adults
and approximately 17% of
children and adolescents in
the U.S. are either
overweight or obese—
exceeding their healthy
weight range.
• Annual cost of overweight
and obesity exceeds $117
billion a year.
 Direct costs (treatment)
 Indirect costs (lost
productivity, disability,
morbidity & mortality)
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The Epidemic of Obesity among U.S. Adults
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1991
2004
1995
2007
2000
No data
<10%
10%-14%
20%-24%
25%-29%
≥30%
15%-19%
Fig. 9-2, p. 293
Problems Associated with Weight
Some people can weigh too much while others
weigh to little.
•Underweight: weight 10% or more below the
desirable weight for height, or a BMI less than
18.5.
•Problems of underweight individuals:
 Possess minimal fat stores.
 Could be at a disadvantage when energy reserves
are needed.
 Menstrual irregularity, infertility, osteoporosis.
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What Is a Healthful Weight?
• Problems of defining a healthful weight
are many.
 For long-distance runners, unneeded
pounds are a disadvantage.
 For swimmers, fat contributes to their
buoyancy and insulates them against the
cold.
 Dancers and models may value thinness so
highly that to attain it, they compromise
their health.
• What range is compatible with wellness
and long life?
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What Is a Healthful Weight?
Body Weight versus Body Fat
• Two people of the same sex, age, and height
may both weigh the same, yet one may be too
fat and the other too thin.
 The difference lies in their body composition.
• Obesity must be defined by amount of body
fat rather than by weight.
• The health risks for obesity refer to people
who are overfat.
• Desirable measures for percent body fat:
 Men 12%-20% (overfat would be >25%)
 Women 20%-30% (overfat would be >33%)
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What Is a Healthful Weight?
Measuring Body Fat
• Body fatness is hard to
measure.
• One very accurate way is
to measure the body’s
density.
 Weight divided by
volume
• Lean tissue is more
dense than fat tissue.
Underwater weighing or
hydrostatic weighing measures
the amount of water displaced.
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What Is a Healthful Weight?
Measuring Body Fat
• Body density can more
easily be determined by
air displacement
methods.
• The BodPod measures
the volume of air
displaced by a person
when seated in a sealed
device of known volume.
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What Is a Healthful Weight?
Measuring Body Fat
• Skinfold Test: Using a
caliper to measure the
thickness of a fold of fat,
the measurement is then
applied to a standard
table to give a fair
approximation of total
body fat.
The fatfold test gives a fair
approximation of body fat.
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What Is a Healthful Weight?
Measuring Body Fat
• Dual energy X-ray
absorptiometry (the
DEXA test) can yield an
accurate image of the
body’s fat-free tissue
and total fat content.
 This test can be costly.
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What Is a Healthful Weight?
Measuring Body Fat
• Bioelectrical
impedance:
estimation of body fat
content made by
measuring how quickly
electrical current is
conducted through the
body.
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What Is a Healthful Weight?
Distribution of Fat
• Central obesity: excess fat
on the abdomen and around
the trunk.
 “Apple-shaped” body
 Strong risk factor for
type 2 diabetes, heart
disease, hypertension,
and other problems.
• Peripheral obesity:
excess fat on the arms,
thighs, hips, and buttocks.
 “Pear-shaped” body
There are health implications
to how body fat is distributed.
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What Is a Healthful Weight?
Weighing In for Health
• A person’s health risk is dependent on three factors:
 Body weight
 Amount and location of body fat
 Current health status
• Body mass index: an index of a person’s weight in
relation to height that correlates with total body fat
content.
 BMI does not account for:
• Location of fat in the body
• Muscular people with a low percentage of body fat
may have a high BMI
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What Is a Healthful Weight?
Waist circumference measurement
provides information about the
distribution of fat in the abdomen.
Disease risk rises when waist
circumference exceeds:
• 35 inches in women
• 40 inches in men
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Benefits of
Using BMI:
• BMI correlates
strongly with
body fatness and
risk of disease
and death.
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Healthy Weight
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What Is a Healthful Weight?
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What Is a Healthful Weight?
Cautions in Using BMI:
• May overestimate body
fat in athletes and
underestimate body fat
in adults over 65.
• A muscular person, such
as this body builder,
often has a low
percentage of body fat
but a high BMI.
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Energy Balance
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Energy Balance
•
•
•
The body expends most of its
energy on basal
metabolism—maintaining
basic physiological processes
such as breathing, heartbeat,
and other involuntary activities.
The second largest amount of
energy is expended for
voluntary physical activities—
an amount that will vary by
activity level.
A minor amount of energy is
also used for the thermic
effect of food—the energy
needed to digest, absorb, and
process the food you eat.
How the Body Expends
Energy
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Thermic effect of food
5%–10%
Basal
metabolism
60%–65%
Physical
activity
25%–35%
Fig. 9-4, p. 299
Energy Balance
• Basal metabolism: the
sum total of all the chemical
activities of the cells
necessary to sustain life,
exclusive of voluntary
activities—that is, the
ongoing activities of the
cells when the body is at
rest.
• Basal metabolic rate
(BMR): the rate at which
the body spends energy to
support its basal
metabolism. The BMR
accounts for the largest
component of a person’s
daily energy (calorie)
needs.
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Energy Balance
• To increase your
metabolic rate, make
exercise a daily habit.
• Body composition
influences metabolic
rate.
 Weight training can
help shift your body
composition toward
more lean tissue,
thereby speeding up
your metabolism.
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Causes of Obesity
Genetics
• Set-point theory: the theory that the body tends to maintain
a certain weight by adjusting hunger, appetite, and food
energy intake on the one hand and metabolism (energy
output) on the other so that a person’s conscious efforts to
alter weight may be foiled.
• An identified gene—named ob (for obese).
 Appears to produce a hormone called leptin (Greek word
for slender).
 It has been reported that as body fat stores increase,
blood leptin increases.
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Causes of Obesity
Genetics
Fat cell theory: states that during the growing years, fat
cells respond to overfeeding by producing additional fat
cells; the number of fat cells eventually becomes fixed,
and overfeeding from this point on causes the body to
enlarge existing fat cells.
• Fat cells of obese people contain higher levels of the
enzyme lipoprotein lipase (LPL), which determines
the rate at which adipose cells store fat.
 Lipoprotein lipase (LPL): an enzyme located on
the surfaces of fat cells that enables the cell to
convert blood triglycerides into fatty acids and
glycerol to be pulled into the cell for reassembly and
storage as body fat.
 The larger the fat cell (and the greater the number
of fat cells), the more LPL and the more easily the
body can pull triglycerides into fat cells for storage.
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Causes of Obesity
Environment
• External cue theory:
the theory that some
people eat in response to
such external factors as
the presence of food or
the time of day rather
than to such internal
factors as hunger.
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Causes of Obesity
A Closer Look at Eating Behavior
• Hunger: the physiological drive to find and
eat food, experienced as an unpleasant
sensation.
• Appetite: the psychological desire to find and
eat food, experienced as a pleasant sensation,
often in the absence of hunger.
• Satiety: the feeling of fullness or satisfaction
that people feel following a meal.
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Causes of Obesity
• Hypothalamus (high-pohTHALL-ah-mus): a part of the
brain that senses a variety of
conditions in the blood, such as
temperature, salt content, and
glucose content, and then
signals other parts of the brain
or body to change those
conditions when necessary.
• Arousal: as used in this
context, heightened activity of
certain brain centers associated
with excitement and anxiety.
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Brain
Brain
stem
Thalamus
Hypothalamus
Spinal cord
p. 303
Causes of Obesity
• Eating behaviors many be a
response to hunger, appetite, and
other complex human sensations.
• Stress may also promote the
accumulation of body fat.
• Probably the most important
contributor to obesity is
underactivity.
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Weight Gain and Loss
• Changes in body
weight can reflect
shifts in fat, fluid,
bone minerals, and
lean tissues (e.g.
muscles).
• Most quick weightloss diets promote
large losses of fluid
with little or no real
loss of body fat.
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Weight Gain and Loss
Weight Gain
• When you eat more calories than you
need, where does this excess go in your
body?
The energy nutrients…
•carbohydrate
•fat
•protein
…contribute to body stores
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Weight Gain and Loss
Feasting: The person is storing energy
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A. When a person overeats (feasting):
Food component:
Carbohydrate
Fat
Protein
is broken down in the body to:
and then stored as:
Glucose
Liver and
muscle glycogen
stores
Fatty
acids
Body fat stores
Amino
acids
Fat after losing
nitrogen in
urine
(first used to
replace body
proteins)
Fig. 9-5a, p. 305
Weight Gain and Loss
Fasting: The person is drawing on stored energy
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B. When a person draws on stores (fasting):
Storage compound:
Liver and
muscle glycogen
stores
is broken down in the body to:
and then used for:
Glucose
Energy
Body fat stores
Fatty
acids
Fig. 9-5b, p. 305
Weight Gain and Loss
Fasting: The person is in ketosis
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C. If the fast continues beyond glycogen depletion:
Body component:
Body protein
is broken down in the body to:
Amino
acids
and then used for:
Glucose
Lose nitrogen in urine
Ketone
bodies
Body fat
Energy
Fatty
acids
Fig. 9-5c, p. 305
Weight Gain and Loss
• Ketosis (kee-TOE-sis): an adaptation
of the body to prolonged (several days’)
fasting or carbohydrate restriction.
Body fat is converted to ketones,
which can be used as fuel for some
brain cells.
• Indirectly, the nervous system begins to
feed on the body’s fat stores and reduces
the need for glucose.
• This spares the muscle and lean tissue
from being devoured and prolongs
starvation.
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Weight Gain and Loss
• Ketosis
 May be harmful by upsetting the acid-base
balance of the blood.
 The body’s lean tissue continues to be lost
at a rapid rate.
 The body becomes conservative and slows
the process of metabolism.
• Requires even fewer calories
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Diet Confusion:
Weighing the Evidence
• Dieting is big business in
the United States.
• Diets work because
people limit their food
consumption.
• Although most diets can
provide a weight loss in
the short term, few
people can lose weight
and keep it off.
• Some diets may be
harmful.
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Weight Gain and Loss
Evaluating Diets
• Systematically eliminates groups of foods.
 Probably lacking in nutrients.
 Hard to adhere to the eating plan.
• Encourages specific supplements of foods only
available from selected distributor.
 May contain harmful or unproven ingredients.
• Touts magic or miracle foods that burn fat.
 The only way to “burn” fat is to increase physical
activity or decrease the amount of calories
consumed.
• Promotes bizarre quantities of one food or
type of food.
 Not good advice, considering human nutritional
needs.
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Weight Gain and Loss
Evaluating Diets
• Has a rigid menu
 No one diet plan will work for everyone.
• Promotes specific food combinations.
 Needlessly restricts dietary intake and choices.
• Promises weight loss of more than two pounds per
week.
 A safe weight loss goal = 0.5-2.0 pounds/week.
• Provide warnings for people with health conditions such
as diabetes and hypertension.
• Does the program encourage/promote physical activity?
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Weight Gain and Loss
Evaluating Diets
• Does the program
encourage an intake very
low in calories?
 Designed for persons
with severe obesity or
health problems.
 Needs vitamin and
mineral
supplementation.
 Should be medically
supervised for adverse
health effects.
 Needs dietary
counseling before
program ends.
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Weight Gain and Loss
Drugs and Weight Loss
• The search is on to find a safe and
effective drug solution to obesity.
• The ideal drug should:
 Be safe and effective for long-term use.
 Free of undesirable side effects & abuse
potential.
 Effective at reducing body fat.
• The successful drug should be combined
with lifestyle changes including a healthy
diet and exercise.
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Weight Gain and Loss
Surgery and Weight Loss
• Surgery may be an option for people
who cannot lose weight by traditional
means and are severely obese.
• Three common types of surgery
include:
1. Gastroplasty (stomach stapling)
2. Gastric bypass
3. Gastric banding
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Small pouch
Esophagus
Surgical staples
Stomach
Duodenum
Bypassed
stomach
Jejunum
Jejunum
Large intestine
In gastric bypass (Roux-en-Y) operations, a small pouch near the top of the
stomach is created with staples or a plastic band and connected directly to the
middle portion of the small intestine (jejunum).
Fig. 9-6a, p. 312
Esophagus
Band
Small stomach
pouch
Duodenum
Stomach
Jejunum
Large intestine
Gastric banding reduces the size of the stomach by using an adjustable silicone
band or cuff near the top of the stomach to create a pouch that fills
quickly and empties slowly. The inflatable band is connected to an access port
placed close to the skin, allowing surgeons to tighten or loosen it to meet an
individual’s needs.
Fig. 9-6b, p. 312
Weight Gain and Loss
Surgery and Weight Loss
• Common side effects of surgical
interventions include:
 Nausea, vomiting, diarrhea, heartburn,
abdominal pain, and band slippage or pouch
enlargement.
 More severe effects include: complications
during surgery, infections and death.
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Weight Gain and Loss
Surgery and Weight Loss
• Cosmetic surgery approaches include:
 Liposuction: a type of surgery (also called
lipectomy) that vacuums out fat cells that have
accumulated, typically in the buttocks and thighs.
• Surgery is appropriate in some instances.
• After surgery, a changed appearance does not
guarantee changed eating habits, a better
personality, reduced interpersonal conflicts, or
any other improvements in the quality of one’s
life.
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Successful Weight-Loss
Strategies
• The secret is a sensible (not to say easy) three-pronged
approach involving:
1. Healthful eating habits
2. Exercise
3. Behavior change
• Such an approach takes tremendous dedication.
• Many of those who complete weight-loss programs lose
about 10% of their body weight, only to regain twothirds of it back within 1 year and almost all of it back
within 5 years.
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Successful Weight-Loss
Strategies
Personalize Your Weight-Loss Plan
• Find the plan that is right for you.
• Think of it as an eating plan that you will
adopt for life.
• A calorie deficit of 500 calories/day for seven
days is enough to lose one pound of body fat a
week.
 Spending an extra 250 calories per day by exercising
will increase the calorie deficit.
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Successful Weight-Loss
Strategies
• Aim for gradual weight loss.
• Expect to reach a plateau.
• Aim for a positive gain in lean
body mass.
• Weight loss and bone health.
Include adequate calcium and weightbearing exercise.
• Adopt a physically active lifestyle.
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Never Say Diet
1. Adopt a nondiet approach to weight loss.
2. Set achievable goals.
3. Focus on health rather than appearance.
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Eating Plan Strategies
1.
2.
Get personally involved.
Adopt a realistic plan, and
then keep track of calories.
3. Make the eating plan
adequate.
4. Emphasize high nutrient
density.
5. Individualize. Eat foods you
like.
6. Stress “dos,” not “don’ts.”
7. Eat regular meals.
8. Take a positive view of
yourself.
9. Visualize a changed future
self.
10. Take well-spaced weighings to
avoid discouragement.
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Successful Weight-Loss
Strategies
Sample Balanced Weight-Loss Diets Using the
MyPyramid Food Guide
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• Strategies for using
exercise for weight
control
1. Make it active
exercise; move your
muscles.
2. Think in terms of
quantity, not speed.
3. Exercise informally,
in daily routines.
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Weight-Gain Strategies
• The healthful way to gain
weight is to build yourself
up by patient and consistent
training while eating
nutritious foods containing
enough calories to gain
weight.
 Choose calorie-dense
snacks.
 Eat more frequently.
 Spend more time eating
each meal: Start with the
calorie-dense food first,
finish with dessert.
 Eat regular, balanced
meals.
Eat more food and add
extra calories.
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Aiming for a Healthy
Weight
• Examine your options.
• Take the edge off hunger
with an appetizer…
• Make specific requests:
reduced and fat-free
dressings…
• Ask for entrees to be
broiled, baked grilled,
steamed or roasted…
• Request fresh fruit for
dessert…
• Hold the sauce or order red
sauces rather than white…
• Inquire about preparation…
• Downsize your order.
• Order a special omelet: egg
substitute...
• Watch out for
overindulgence
• Take time to enjoy your
meal…
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Eating Well on the Run
• Sandwich Shop: Fresh
sliced veggies in a pita
with low-fat dressing…
• Rotisserie Chicken:
Chicken breast (remove
skin), steamed
vegetables…
• Fast Food: Grilled
chicken breast sandwich
(no sauce)…
• Salad Bars: Broth-based
soups, fresh greens, lowfat dressing…
• Asian Take-Out: Wonton
soup, steamed vegetable
mixtures over rice or
noodles…
• Pizza Night: Choose
flavorful, low-fat
toppings such as
peppers, onions…
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Breaking Old Habits
• Behavior
modification – a
process
developed by
psychologists for
helping people
make lasting
behavior changes.
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Elements of Behavior Change
1. Precontemplation:
You need to change,
but you’re not yet
ready to accept that
fact.
2. Contemplation: You
want to change, but
you’re not sure
how.
3. Preparation: You
gain knowledge to
set up a plan of
action for change.
4. Action: You jump in
and “just do it.”
5. Maintenance: You
work on sticking to
your plan of action.
6. Termination: You
have achieved
lasting change and
experience few, if
any, temptations or
relapses.
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Continued Motivation
• Persist long enough to experience the
rewards, such as improved self-image
and enhanced self-esteem.
• Remember the price of the old
behavior.
• Keep in mind where you started.
• Tune in to the benefits of the new
behavior.
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Addressing Overweight in
Children
• The increasing prevalence of
overweight is now the most
important public health challenge
in the U.S.
• The number of overweight children
in the U.S. has tripled.
• Increases are greater among
Hispanics and African Americans
and are greater in the South.
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Addressing Overweight in
Children
• The same adult diseases associated
with overweight adults, such as type 2
diabetes, high blood lipids, high blood
pressure, and gallbladder disease are
appearing in kids.
• Overweight children are at risk for
injury to weight-bearing joints,
decreased quality of life, depression,
poor self-esteem, respiratory problems,
and sleep disturbances.
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Addressing Overweight in
Children
Helping Children Learn Good Habits
• Parents can set good examples.
• Discourage eating while watching TV and
doing homework.
• Eat meals together as a family and keep fastfood meals to a minimum.
• Encourage children to eat only when hungry.
• Limit high-fat or high-sugar foods.
• Include children in food preparation.
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The Eating Disorders
• Eating disorder: general
term for several conditions:
 Anorexia nervosa
 Bulimia nervosa
 Binge-eating disorder
…that exhibit an excessive
preoccupation with:
 Body weight
 Fear of body fatness
 Distorted body image
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The Eating Disorders
• Anorexia nervosa:
Literally “nervous
lack of appetite,” a
disorder (usually
seen in teenage
girls) involving selfstarvation to the
extreme.
 an = without
 orexis = appetite
For many people with anorexia
nervosa, a full day’s diet may
consist of no more than 3 or 4
items.
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The Eating Disorders
• Bulimia nervosa, bulimarexia
(byoo- LEE-me-uh, byoo-lee-maREX-ee-uh): binge eating (literally,
“eating like an ox”). Combined with an
intense fear of becoming fat and usually
followed by self-induced vomiting or the
taking of laxatives.
buli = ox
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The Eating Disorders
Bulimia nervosa
• Two types:
 Purging type: the person regularly engages in selfinduced vomiting or the misuse of laxatives,
diuretics, or enemas.
 Nonpurging type: the person uses other behaviors,
such as fasting or excessive exercise, but does not
regularly engage in self-induced vomiting or the
misuse of laxatives, diuretics, or enemas.
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The Eating Disorders
• Binge-eating disorder: an
eating disorder
characterized by
uncontrolled chronic
episodes of overeating
(compulsive overeating)
without other symptoms of
eating disorders.
 Typically, the episodes
of binge eating occur at
least twice a week on
average for a period of
six months or more.
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The Eating Disorders
• Disordered eating: eating food as an
outlet for emotional stress rather than in
response to internal physiological cues.
• Unspecified eating disorders: some
people suffer from unspecified eating
disorders; that is, they exhibit some but not
all of the criteria for specific eating disorders.
 2010 Cengage-Wadsworth
 2010 Cengage-Wadsworth