Health Psychology

Obesity – Part 1Chapter 8PY 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; Extreme Risk

BMI > 30, or ~ 30 lbs. overweight for 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 30-55 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 andlowered metabolic rate acts to restore the lost weightenergy 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 bad-tasting ice cream but the obese participants ate much more good-tasting 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?

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.

http://www.bigtexan.com/72ozlive.htm

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.