Health PSYCHOLOGY
Weight management
and Obesity
Weight Management -- Overview
Physical activity (what does “Obesity” article say?)
Dietary choices (what does “Obesity” article say?)
Caloric needs
Vary by age, sex, height, weight, activity level, & basal
metabolic rate (BMR)
Rough guideline (men = 2500 kcal, women = 2000 kcal)
Mood regulation
Cultural factors
ENERGY IN
ENERGY OUT
BODY MASS and
COMPOSITION
GENES
Assessing body composition
Estimating percentages of fat, muscle, bone
Is there an “ideal” body comp?
Bioelectrical impedance — determining
body fat percentage by analyzing electrical resistance
(fat is a poor conductor)
Skin calipers — thickness of subcutaneous fat in
multiple places on the body
Body mass index (BMI) – used to estimate a healthy
body weight based on a person's height, assuming an
average body composition.
Body Mass Index (BMI = kg/m2)
http://www.nhlbisupport.com/bmi/
BMI Categories:
Underweight = <18.5
Normal weight = 18.5-24.9
Overweight = 25-29.9
Obesity = BMI of 30 or greater
When we eat too much…
or move too little (or both)
Obesity (particularly “apple-pattern”)
linked to atherosclerosis, hypertension,
diabetes
Increased risk of several cancers, sleep
disturbances, degenerative joint disease
Impact on psychological well-being
Increased mortality rates (next slide)
Relationship between BMI and
Mortality
Factors That Contribute
to Obesity
Heredity / biological factors
Cultural factors
Emotional / behavioral factors
Basic physiological cues
Body needs energy =
sends orexigenic signal
(tells brain to switch
hunger on)
Ghrelin (hormone)
Body has sufficient
energy = sends
anorexigenic signal
(tells brain to switch
hunger off)
Leptin (hormone)
Smell
Only sense
directly
connected to
forebrain
Olfactory
receptor
neurons (350
ORNs)
Strong cue for
eating,
emotion, and
memory
10
Taste
Taste buds (5 different types)
Salt, sour, bitter, sweet, umami (savory)
each contains several types of taste
receptors (microvilli) that react with tastant
molecules in food
Taste is influenced by many factors
11
Metabolism and weight
Basal Metabolic Rate (BMR)
base rate of energy expenditure
influenced by heredity, age, activity level, and
body composition (fat tissue has a lower
metabolic rate)
Set Point
the point at which an individual’s “weight
thermostat” is supposedly set
when the body falls below this weight, an
increase in hunger and a lowered metabolic
rate may act to restore the lost weight
“Is it genetic?”
ob gene
Regulates production of leptin
Leptin is secreted by fat cells and has dual
activity of decreasing food intake and
increasing metabolic rate
Mice born without the ability to make leptin
(ob/ob mice) eat without restraint
ob/ob mouse
normal mice
ob/ob mouse
ob/ob mouse
ob/ob mouse
injected with
leptin
So, just give obese
humans leptin!!!
In fact, this works in leptin-deficient
humans, but…
99.99% of obese humans have HIGH
levels of leptin, but have become
insensitive to it.
Hereditary factors
The genetic contribution to body weight is
estimated to be between 40 and 70 percent
(with some rare cases of severe obesity
linked to specific gene errors)
 Body weights of adopted children correlate
more strongly with weights of biological
parents
The epigenetics of increasing weight through
the generations -- Maternal obesity could promote
obesity in the next generation. (Waterland, 2008)
Obesity Trends
 http://www.cdc.gov/obesity/data/trends.html
Will the trend continue?
Factors That Contribute
to Obesity
Heredity / biological factors
Cultural factors
Emotional / behavioral factors
10,000 years ago –
who survived during a famine?
OR
ENERGY IN
ENERGY OUT
Most are not in a
famine anymore…
Increased
availability of
high density foods
(sugar/fat are cheap)
Increase in size
Decrease in workrelated activities
Decrease in activities
of daily living
BODY MASS
Decrease in cost
Genetic predisposition to store fat
Just as
our jeans no longer fit our waist,
our genes no longer fit our
environment
Social/Cultural Factors
in Obesity
We live in a toxic environment. It’s like trying to
treat an alcoholic in a town where there’s a bar every
ten feet. Bad food is cheap, heavily promoted, and
engineered to taste good. Healthy food is hard to
get, not promoted, and expensive.
If you came down from Mars and saw all this, what
else would you predict except an obesity epidemic?
Kelly Brownell, Yale, 2004 (Nat’l Geo. Article: The heavy cost of fat)
Social/Cultural Factors
in Obesity
Food-toxic environment (cheap, hi-cal, lo-quality
food available)
 Absence of supermarkets in lo-income
neighborhoods
 Way too many of our calories are coming from junk
food (and in the car). (Sugar: 172 lbs/pp per year)
 Governmental subsidies (e.g., Zea Mays, a giant
tropical grass)
 We are simply eating more! (next slides)
Humongasize it!!
Past
Today
French Fries
2.4 oz
210 kcal
7 oz
610 kcal
Soda
6.5 oz
79 kcal
20.0 oz
250 kcal
Hershey’s Bar
2 oz
300 kcal
7 oz
1000 kcal
POPCORN
20 Years Ago
270 calories
5 cups
Today
1700 calories
21 cups buttered
Social/Cultural Factors
in Obesity
•2004: The "Monster
Thickburger" — two 1/3pound slabs of Angus beef,
four strips of bacon, three
slices of cheese and
mayonnaise on a buttered
sesame seed bun
•1420 calories!
Social/Cultural Factors
in Obesity
Cultural variation in ideal body image
(overemphasis on thinness  yo-yo
dieting and eventual weight gain)
Studies on immigrants: e.g., JapaneseAmerican men are 3 times as likely to be
obese as men living in Japan
Pima Indians (next slide)
Social/Cultural Factors
in Obesity
Pima Indians (in Mexico vs. in U.S.)
Emotional / behavioral
factors
Disinhibition — overeating triggered by an
event, emotion, or behavior
Eating used as coping
Internality / Externality hypothesis
People are sensitive to external cues,
perhaps more so in overweight individuals:
Time of day
Commercials
“Golden arches”
Dieting concerns
Dieting
In U.S., 72% of women and 44% of men
have dieted at some point in their adult lives
Yo-yo dieting associated with progressive wt
gain
Chronic dieting influence BMR negatively
Fad diets and health problems
Eat an Apple (Doctor’s Orders)
Doctors at three health centers in
Massachusetts have begun advising
patients to eat “prescription produce” from
local farmers’ markets, in an effort to fight
obesity in children of low-income families.
Now they will give coupons amounting to
$1 a day for each member of a patient’s
family to promote healthy meals.
NYTimes Aug 13, 2010
Eat an Apple (Doctor’s Orders)
Cultural interventions
Farm to table to school movement
Etc.
Healthy Weight Loss
Cognitive-behavioral program
Goal-setting, monitoring, social support
L.E.A.N.
Lifestyle changes (stimulus control, selfmonitoring, speed, etc.)
Exercise
Attitude
Nutrition
Stepped
Care for
Obesity