Health Psychology Chapter 15: Eating

1
Health PsychologyChapter 15 Eating Dieting

• Mansfield University
• Dr. Craig, Instructor

2
The Digestive System

• Human body converts foods (plant and animal
  tissue) into usable components (fats, proteins,
  carbohydrates, vitamins minerals).
• Materials transported through bloodstream to need
  areas or to be stored
• Salivary glands- part of taste sensation,
  contains enzyme to break down starches
• Peristalsis-rhythmic contraction and relaxation
  of muscles lining digestive tract starting in
  esophagus
• in the stomach it moves food and mix with gastric
  secretions (high acidity) such as pepsin which
  works on proteins.

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Digestion Continued

• Small Intestine
• balance pH of stomach mix by secreting
  alkalinic pancreatic juices that also help digest
  CHO and fats
• absorption of starches
• fats broken down by bile salts stored in gall
  bladder and made in liver
• fluids absorbed and nutrients/electrolytes
  extracted
• Large Intestine
• further absorption of H20 and manufacture some
  vitamins
• The Brain
• Hypothalamus and hyper insulin secretion--
  adipose
• Cholecystokin (CCK)- satiety Leptin- reduced
  food intake, increased activity levels

4
Weight Maintenance

• Weight flux calories burned calories consumed
• Consumed
• CHO (sugar, starches) 4 kcals/gram
• Proteins 4 kcals/gram
• Fats 9 kcals/gram
• Alcohol 7 kcals/gram
• Fats highest concentration of kcals, alcohol
  most selectively taken by system
• Burned
• daily metabolism
• activities of daily living
• exercise
• metabolism varies individually, and under
  different conditions
• consider weight loss and gain research!!

5
Experimental Starvation

• Ancel Keys Research on Normals
• Design-
• 3 months as usual eating
• Reduce ration until 75 of current weight
  (half-rationing)
• 3 months refeeding
• Results
• rapid weight loss pace originally that slowed to
  a crawl- had to cut under half rations to lose
  weight
• irritable, aggressive, neglectful of hygeine
  appearance
• food obsessed
• during refeeding, most men over ate and gain more
  than previous normal weight
• many did not return to previous mood state

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Experimental Overeating

• Sims Research- to gain 20-30 pounds
• population of prisoners
• Findings
• initial weight gain with the doubling of diet.
  After that a slow down in weight gain requiring
  even more.
• Food became repulsive
• after study.. Most returned quickly to normal
  weight

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Obesity

• What can these experiments tells us about common
  perceptions of eating and obesity?
• Metabolism changes with eating not fast to
  change suggests we have individual levels of
  weight we naturally maintain.
• Measuring Obesity
• weight-- muscle, bone and adipose tissue (fat)
• key is to measure fat and not other components
• difficult to to with out expensive equipment
• CAT scan, MRI, Dual-Xray, Ultrasound
• How can we know then?

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Measuring Obesity- Useful measurement

• Skinfold technique- /-3.5
• Water Immersion- the archimedes principle
• Waist-hip Ratio- relative distribution of fat,
  but not fatness though
• carry fat high (apple) or low (pear)
• Body Mass Index- kg /m2-- a measure of body
  density relative to height. (See also 15.1 in
  text)
• 27.8 women 27.3 men
• who doesnt this work well for?
• Met Life Height-Weight charts (15.2)

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Obesity on the Increase

• Overall obseity in US has increased by 1/3 in the
  past 20 years
• People (more women) increasingly conscious of and
  dissatisfied with bodies even if weight is
  normal.
• On diet even if BMIlt25
• Dieter have 50 more weight flux than non-dieters
• Increasing use of dangerous dietary methods.

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Explanatory Models of Obesity

• Why are some people obese?
• Set-Point Model- weight regulated by a preset
  internal standard
• studies on experimental starvation and dieting
  are consistent with this.
• Metabolism changes to counter extreme changes
• Problems--
• why may some peoples set-point be at obesity
• twin studies suggest genetics are a component
  (more so for women apparently)
• People can/do become obese from overeating
• Why has obesity increased drastically in recent
  years
• a set point not consistent with evolutionary
  theory

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Explanatory Models of Obesity

• Positive Incentive Model- the positive
  reinforcers of eating have important consequences
  for weight maintenance
• people learn to regulate their eating
• Power of incentive varies with
• personal pleasure in eating
• social context
• biological factors
• Explain variability in obesity
• food abundance/availability/ VARIETY (research)
• advertising programs

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Obesity Health (See research summary 15.4)

• Complex question Is obesity in and of itself,
  bad for ones health
• moderately overweight-- probably not
• severely (morbid obesity BMI40)-- definitely
• healthiest BMIs are around 27
• The U-Shaped Relationship for weight health for
  all-cause mortality.
• Relationship between weight and CVD risk tends to
  disappear after 65 years (why do you think?)
• Yo-Yo dieting/Weight Cycling/Weight Loss gt20 lbs
• more predictive of mortality (even if weight loss
  intentional, why do you think?)
• Weight Distribution- Apple (2.3X risk) Pears
• Is dieting healthy? Look above!! Some gain
  actually may be healthy! (Andres, 1995)

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Getting Fatter and Dieting More in the USA

• Why are more people gaining weight than ever?
• research shows people are less active than ever
  (CATV,videos etc) more likely to eat fast food
  than ever. (Jeffrey French,1998)
• reduced fat intake (?) but this savings has been
  exchanged for marked increase in simple sugars.
• Dieting has become big business in a fatter USA
• we are highly weight conscious
• 1960s- 10 of adults overweight were dieting
• 2000- between 50-70 of adults are/have
  moderated dietary behavior even for those not
  morbidly obese
• 70 of high school girls 20 of boys

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Losing Weight

• 1. Restricting type and amount of intake
• smaller portions, different types of food
• Low Carb- High Fat and Protein
• Sugar Busters and Atkinss Diet
• potentially dangerous diet not based on many
  experts claim is based on inaccurate readings of
  literature.
• High Carb- Very Low Fat (15 or less)
• Ornish Diet and many vegetarian diets
• difficult and extreme diet leaving little room
  for fudging
• good evidence that it reverses atherosclerotic
  deposits
• Liquid diets-
• nutritionally balanced, but very boring! Often
  administered typically in hospital settings for
  morbidly obese (VLCD)

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Losing Weight

• 2. Changing Eating Behaviors
• Behavior modification approaches- eating and
  craving diaries kept, table behaviors (slow down,
  leave food, chew etc.), awareness training of
  what and when certain foods are eaten.
• reinforcement of good eating habits, not weight
  change!
• 3. Exercise
• speeds up metabolism, counters metabolic slowdown
  during dieting alters distribution of fat
  independently.
• 4. Drastic Methods- lipo, drugs, stomach
  surgery, VLCD

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Success and Failure in Dieting

• Maintaining weight loss is very difficult but
  odds are improved with
• formal programs with post treatment programs
• include social support, exercise outlets,
  continued therapist contact
• Perri et al, 1988-
• 17 non- post treatment maintained
• 67 post treatment maintained
• self-efficacy
• Obese children who lose weight are more likely to
  keep it off