Transcript Introduction to Psychology
Health PSYCHOLOGY
W
eight management and
O
besity
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 body fat percentage by analyzing electrical resistance (fat is a poor conductor) — determining Skin calipers — thickness of subcutaneous fat in multiple places on the body Body mass index (BMI) – body weight based on a person's height, assuming an average body composition .
used to estimate a healthy
Body Mass Index (BMI = kg/m 2 )
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
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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
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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?”
o b 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 estimated to be between 40 and 70 percent (with some rare cases of severe obesity linked to specific gene errors) is 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 cost
BODY MASS
Decrease in work related activities Decrease in activities of daily living 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!!
French Fries Soda Hershey’s Bar Past 2.4 oz 210 kcal Today 7 oz 610 kcal 6.5 oz 79 kcal 20.0 oz 250 kcal 2 oz 300 kcal 7 oz 1000 kcal
POPCORN 20 Years Ago Today 270 calories 5 cups 1700 calories 21 cups buttered
Social/Cultural Factors in Obesity
•2004: The "Monster Thickburger" — two 1/3 pound 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., Japanese American 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, self monitoring, speed, etc.) Exercise Attitude Nutrition
Stepped Care for Obesity