Health Psychology
Obesity – Part 1
Chapter 8
PY 470 Hudiburg
What is obesity?
 Ways to determine Ideal
Body Weight – body
composition, especially fat
 Weight for Height Tables:
Metropolitan Life Insurance
Table – Table 8.1, p. 269-270
 Body Mass Index –
Weight (kg)/ height (MxM)
or (weight (lb)/ height (in x
in) )x 705
For example 5’10” person
weighing 150 #
BMI = (150/ (70 x70)) x 705
= 21.6
compare to Table 8.2, p.
270-271
BMI Classifications
 BMI = 19-25; Normal;
Low Risk
 BMI = 25-30; Moderately
overweight; Some Risk
 BMI = 30-35; Class 1
obesity; High Risk
 BMI = 35-40; Class 2
obesity; Very High Risk
 BMI> 40; Class 3 obesity;
BMI > 30, or ~ 30 lbs. overweight for
Extreme Risk
5'4" person for 2005 - CDC
What is obesity?
 Americans overweight – 66%
adults (BMI 25-29), 23%
obese – CDC (2003) – school
age obesity 15%
 Approximately 325,000 deaths
and $39 to $52 billion in
health care costs have been
attributed to obesity annually
(Flegal, Carroll, Ogden, &
Johnson, 2002).
 Rates by gender and ethnic
group – F 8.1, p. 272
 33% increase in the past 20
years in U.S.
 Rates in other countries have
increased – F 8.2, p. 273
What are the consequences
of obesity?
 Physical consequences
 increased risks of hypertension, kidney
disease, diabetes, cardiovascular disease,
and some type of cancer
 Some studies have found as much as a
seven-fold increase in coronary heart
disease (CHD) with a BMI of 35 or
greater (Ellis, Elliott, Horrigan, Raymond,
& Howell, 1996).
 Manson et al. (1990) – F 8.3, p. 273,
women in top 20% BMI are 3 ½ times
more likely to die from CHD than lowest
20% BMI – based on 115,886 women 3055 years old in 1976
 Lowest rate of CHD: 18.6 – 23 BMI for
females and 19.9 – 22.6 BMI for males –
American Cancer Society
 Problems with type 2 diabetes – 80% of
case are obese and concern for growing
number of overweight children and
adolescences – Sinha et al. (2000)
Social/Psychological Effects of Obesity
 Being perceived as obese can affect how you are treated and how you
feel about yourself.
 Stereotype obese as slow, lazy, and sloppy, less sincere, less friendly,
meaner, and more obnoxious – Rychman et al. (1989)
 Black women are less critical of large black women than white women
are of large white women
 Obese people are frequently victims of ridicule and job discrimination
 Obese women are less likely to be married and make less money than
comparison groups
 Weight discrimination is greater than race and gender discrimination
and occurs at every stage of employment (hiring, placement,
promotion, compensation, discipline, and discharge)
 Negative social attitudes even in young children age 5 – Richardson et
al. (1961)
 Reasons for negative attitudes – it under the persons control he/she
could stop eating if he/she wanted to stop – Dejon (1980) study of
likeability of normal weight and overweight pictures of girls
 Personality characteristics are the same for obese and non-obese
persons
Genetic Factors
Twin studies reveal a genetic influence on body
weight: - F 8.5, p. 276 – Grile & Pogue-Geile (1991)
Weight resemble those of biological parents
Identical twins have closely similar weights and BMI,
even when reared apart Being overweight is not simply a matter of sacrificing too
many hot fudge sundaes
Losing weight is not merely a matter of mind over
platter.
Stronger relationship between adopted children’s and
biological parent’s weight than adopted parent’s weight –
F 8.5, p. 276
Obese parents and obese children – 7% neither
parent, 40% one parent, and 80% both parents
Causes for Obesity: Genetic
Inheritance
Leptin: a protein found that suppresses appetite
in animals and increases metabolism
Overweight animals lack the protein Leptin
Overweight people aren’t as responsive to Leptin as
are normal weight people. Leptin is actually higher in
overweight people than normal weight people
Higher in eating disorders (i.e., BED), higher in sleep
deprived, Anorexia Nervous have hypoleptinaemia
Metabolism rates influenced by genes – high
rates don’t gain and low rates gains weight
Food preferences for obese men and women –
Table 8.3, p. 277 – the comfort food?
Set Point Theory
The point at which an individual’s “weight
thermostat” is set
When body falls below this weight,
an increase in hunger and
lowered metabolic rate acts to restore the lost weight
energy expenditure decreases
Some researchers doubt that the body has a
precise set point that drives hunger and believe
slow, sustained changes in body weight can
alter one’s set point
Hunger is determined by many factors, including
learned incentives.
Basal Metabolic Rate
The body’s resting rate of energy expenditure
To maintain the body’s set point weight, your
body adjusts not only food intake and energy
output but also the metabolic rate.
By the end of their 24 week semi starvation, the
subjects in Ancel et al. (1950) research had stabilized
at ¾ their normal weight – while eating half of what
they previously did. Study was done in the 1930s in
Minnesota.
In a reverse experiment (Levine et al., 1999) in which
volunteers were overfed 1000 calories a day for 8 wks –
some gain average of 9 lbs. when others 1 lb. - those who
gained the least weight tended to spend the caloric energy
fidgeting more.
Genetic factors or
environmental factors?
Genes mostly determine why one person today is
heavier than another. Environment mostly
determines why people are heavier today than 50
years ago.
While the average North American woman weighs more than her
counterpart of 40 years ago and obesity rates are increasing,
today’s average Miss America contestant weights about 15 pounds
less than 40 years ago.
Genetic factors predict 40-70% of variation in BMI
Genes for weight gain predisposes some
individuals towards weight gain
Environment determines which of those
individuals actually gain weight
Genetic factors or
environmental factors?
 Genes do not totally predict
weight
rates of obesity in US have
increased dramatically in recent
years
people with same genetic make-up
who live in different areas of the
world often have different body
weights (e.g., Japanese who move
to Hawaii are heavier than those
who stay in Japan)
How do psychological factors
influence eating (and overeating)?
Internal-external hypothesis
people ignore internal cues
(i.e., hunger), and pay
attention to external cues (i.e.,
taste, smell, variety)
Limitations: -people of normal
weight are not particularly
good at interpreting internal
signals for hunger
people of varying weights
are good at responding to
external cues for eating
Internal/external hypothesis
PUSHED by physiological state (internal) and PULLED
by psychological state (external).
External Incentives and Hunger
Judity Rodin and Joyce Slochower (1976)
External girls (could not resist M&Ms) gained the most weight.
Rodin (1984)
Subjects had gone 18 hours without food
While blood samples were taken a juicy steak was wheled in, crackling as
it was taken off the grill
Rodin monitored their rising blood insulin levels and their feelings of
hunger
“Externals” had the greatest insulin increase and accompanying hunger
response.
External incentive (steak) affects internal physiological state.
Internal/external hypothesis
 Increased variety of foods leads to increased consumption even in
rats – Sclafani & Spring (1976)
 Box 8.1, p. 279 Schacter et al. (1968) test of the internal/external
hypothesis. Used a “cracker rating test”, the number of crackers
eating by normal weight persons was influence by just eaten a
large meal but there was no influence for overweight persons – F
8.6, p. 280
 Nisbett (1968) ice cream study used good-tasting and bad-tasting
ice cream, neither non obese nor obese participants ate much badtasting ice cream but the obese participants ate much more goodtasting ice cream than non obese participants
 Culture and Hunger
 Cultural preferences vary with exposure
 We tend to dislike unfamiliar (including novel foods)
 Research suggests with repeated exposure , their appreciation for new tastes
increases; exposure to one set of novel foods increases willingness to try
another.
 Little recent support for hypothesis
How do psychological factors
influence eating (and overeating)?
Mood regulation
people eat to make themselves feel better when they
experience stress, anxiety, or depression – Pine
(1985)
this tendency is more common for women than men
Females eat more when depressed than males, college
student study by Rozin & Fallon (1988)
mixed evidence: obese students eat more during
exam period than students of normal weight (no
difference during less stressful times). Stress does
not lead everyone to overeat, especially men.
How do psychological factors
influence eating (and overeating)?
 Restraint theory – internal physiological signals cue
hunger – Herman & Pevy (1984)
when people are trying to lose weight they ignore internal signals,
and use cognitive rules to limit their intake
Cognitive rules related to “forbidden foods” and “all-or-none”
approach. If violated all is lost therefore over consumption occurs
Herman & Mack (1975) found in a study when participants were
given either none (control), one, or two milkshakes prior to tasting
three ice creams to rate. Participants were allowed to eat as much
ice cream to get a rating. Data in F. 8.7, p. 283, dieters consumed
more than non dieters as compared to controls.
Mood influences eating in restrained eaters, when played sad
music restrained eaters ate more – F 8.8, p. 285
Restraint theory not always a good predictor of eating behavior –
Lowe (1993)
How do psychological factors
influence eating (and overeating)?
 Lifestyle and culture
 people eat more when with others –
social cues – The turkey eating orgy and
don’t forget the pecan pie with ice
cream.
 What mothers eat while pregnant may
influence taste preferences in children –
Mennela et al. (2001) study with
expectant mothers drinking carrot juice
 culture influences types of food and
tastes – dog or snake for dinner? Bugs
are a good source of protein.
 cultural factors like availability and
amount of food contribute to obesity –
U.S. has highest rate of obesity –
change in proportions over the years,
the “supersize” generation and video
games.
Portion size?
http://www.bigtexan.com/72ozlive.htm
Big Texan Steak Ranch Home of the free 72
ounce steak dinner- eat it in an hour and it’s free (if
not, it’s $72). Are you man, or woman, enough?
About 42,000 have tried and 8,000 have succeeded.
Pro Wrestler Klondike Bill ate two in an hour back in
the 1960s, while the quickest anyone finished was
in 9 1/2 minutes by Frank Pastore (he has done it 7
times) in 1987, former major league pitcher and
now religious radio talk host. An 11 year old has
succeeded.
Portion size?
 Largest Hamburger – The “Absolutely Ridiculous Burger”
was recently prepared in February 2008 at Mallie’s
Sports Bar and Grill in Detroit. The burger weighs 134
pounds, with cheese and bacon. The bun weighs 50
pounds. The burger must be order 24 in advance and
takes 12 hours to prepare and costs $350. Previous
record was 123 pounds.