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Types of Exercise Aerobic Exercise
Elevated heart rate and respiration
Weight training Resistance important for development of lean
muscle mass
Increased activity Increasing daily movement to improve fitness
Benefits of Exercise - Physiological Increases in cardiovascular fitness and
endurance 30-minute/day decreases the risk of chronic disease
Improved circulation Strengthens bones and increases joint flexibility Improves digestion and fat metabolism Increases muscle strength and tone Increased longevity
by age 80, the amount of additional life attributable to aerobic exercise is between 1 and 2 years
Benefits of Exercise - Psychological
Psychological Effects of Exercise Improved mood
Exercise as effective as therapy for depression for most people
Decreased anxiety May decrease stress and protect against effect
of stressors Exercise addiction?
Exercise: Determinants of Regular Exercise
Exercise schedules are usually erratic Lack of time and stress undermine good intentions About 50% of people who initiate a voluntary exercise
program are still doing it after 6 months
Individual Characteristics Gender, weight, social support, self-efficacy predict
exercise adherence
Characteristics of the Setting Convenient and accessible settings predict adherence
Exercise: Characteristics of Interventions Strategies
Stages of Change model helps understand levels of motivation
Cognitive-behavioral strategies promote adherence Telephone and mail reminders are effective in relapse
prevention
Individualized Exercise Programs Understanding motivation and attitudes aids in
development of a program of activities that are liked and are convenient
Maintaining a Healthy Diet:Overview
Controllable risk for many causes of death 35% of U.S. population gets 5 servings of fruit and
vegetables each day Unhealthy eating contributes to 300,000+ deaths
per year Dietary change is critical for those at risk for
Coronary artery disease, hypertension Diabetes Cancer
Weight Gain/Loss Formula
Wt +/- = cal absorbed through food
-------------------------------------
cal spent through metab. & activity
Basal Metabolic Rate and Caloric Intake
Basal Metabolic Rate (BMR) Body’s base rate of energy expenditure Influenced by heredity, age (higher in younger people),
activity level, and body composition (fat tissue has a lower metabolic rate)
Calorie amount of energy needed to raise the temperature of 1 g of
water 1 degree Celsius
Weight Regulation
The Search for Hunger/Satiety Signals Feelings of hunger rise and fall with levels of glucose and insulin Possible link to the number of fat cells in the body
Lateral Hypothalamus (LH) Stimulation leads to hunger Lesioning leads to self-starvation
Ventromedial Hypothalamus (VMH) VMH lesioning leads to hunger VMH stimulation causes an animal to stop eating
Short-Term Appetite Regulation Pancreas hormone insulin helps convert glucose into fat When glucose levels fall, insulin productions increases
and we feel hungry Cholecystokinin (CCK) — satiety hormone produced by
the intestine Ghrelin — appetite stimulant produced by stomach
Long-Term Weight Regulation Laboratory mice with a defective gene for
regulating the hormone leptin become obese
Leptin levels increase with body fat Neurons in the arcuate nucleus (ARC) of
the hypothalamus contain many receptors for leptin
Obesity: Some Basic Facts Measuring Obesity
Body mass index (BMI) — measure of obesity calculated by dividing body weight by the square of a person’s height
Mortality Rates and BMI Generally speaking, thinner people live longer;
however, very thin people do not have the lowest mortality rates
Weight Control: Why Obesity is a Health Risk
Links with other risk factors, i.e., blood pressure Increases risks during surgery, anesthesia
administration, and childbearing Chief cause of disability
number of people aged 30-49 who cannot care for themselves has jumped by 50%
Problems with health care May not fit in standard wheelchairs X-rays may not penetrate far enough Blood pressure cuffs may not fit
Hazards of Obesity
Male-pattern obesity linked to atherosclerosis, hypertension, diabetes
Complications after surgery Increased risk of several cancers Increased mortality rates from all causes Impact on psychological well-being Metabolic syndrome Weight cycling — repeated weight gains and losses through
repeated dieting
Obesity Theories Set-Point Hypothesis
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
Positive Incentive Model Food tastes good and is a powerful reinforcer for
eating behavior Social factors and other pleasurable aspects of
eating are part of what is reinforcing.
The Biopsychosocial Model of Obesity - Biology
Heredity Genes thought to contribute approximately 50%
to the likelihood of obesity 60% of obese people had obese biological parents Body weights of adopted children correlate more
strongly with weights of biological parents Body weights of adopted siblings weakly correlated
The Biopsychosocial Model - Psychology
Stress has a direct effect on eating Especially true for adolescents
Greater stress tied to Eating more fatty foods Eating less fruit and vegetables Skipping breakfast More between-meals snacks
Weight Control: Stress and Eating 50% eat more when under stress
Women more likely to eat more under stress Stress removes self-control in dieters/obese Choose foods containing more water, “chewier” Choose salty, low calorie foods Negative emotions – sweet, high-fat foods
50% eat less when under stress Men, compared to women, eat less under stress Non-dieting, non-obese suppress hunger cues
The Biopsychosocial Model - Social
1975: 47% of Americans are overweight or obese 2006: 65% are overweight or obese More prevalent among African-Americans,
Hispanic-Americans, Native Americans Inversely related to socioeconomic status
The Biopsychosocial Model - Social
Cultural variation in ideal body image African-Americans may be less
preoccupied with thinness than European Americans
Acculturation of dietary customs Japanese-American men are 3 times as
likely to be obese as men living in Japan
Weight Control: Factors Associated with Obesity
Particular risk to “apples” rather than “pears” (fat localized in abdomen) More psychologically reactive to stress Greater cardiovascular reactivity
Yo-Yo dieting Loss and regain Affects abdominal fat
Weight Control: Factors Associated with Obesity
Obesity and Dieting as Risk Factors Obesity is a risk factor for obesity High basal insulin levels prompt overeating due
to increased hunger Obese have larger fat cells Cycles of dieting lower metabolic rate
Dieting
Dieting Successful weight loss is often defined as at least a 10% reduction
of initial weight that is maintained for one year 72% of women and 44% of men report having dieted at some point
Why Diets Fail People are not accurate at estimating calorie needs Dieters underestimate consumption People find diets hard to stick with
Diet and Disease Body expends only 3 calories to turn 100 calories of fat
in food into body fat Body expends 25 calories to turn 100 calories of
carbohydrate into body fat Humans have a natural craving for fat (a legacy from our
evolutionary past when food was not plentiful?) Typical Western diet: 40%–45% of total calories are
from fats Poor diet (especially saturated fat) is implicated in one-
third of all cancer deaths in the United States
Weight Control: Treatment of Obesity
Amazon.com has 140,000 titles about dieting Obese individuals attempt to lose weight because
It is considered unattractive (a primary reason) It carries a social stigma (a primary reason) They perceive that it is a health risk It is coupled with psychological distress
Obese - often blamed for their weight Few health practitioners advise losing weight
Maintaining a Healthy Diet:Interventions to Modify Diet Individual interventions
In response to specific health risk Education and self-monitoring are key Cognitive-behavioral interventions
Transtheoretical Model of Change - Different interventions are required for each stage
Precontemplation Contemplation Preparation Action Maintenance
Weight Control: Treatment of Obesity
Dieting Small losses, rarely maintained for long Risk of yo-yo dieting to CHD > than risk of obesity alone Formal investigation of low-carb diets does not suggest they are
more effective than other kinds of diets Fasting – usually employed with other techniques Surgery – stomach stapled to reduce capacity Appetite-Suppressing drugs The multimodal approach
Screening, self-monitoring, control over eating, exercise Controlling self-talk, social support, relapse prevention
Behavioral and Cognitive Therapy Most behavior modification programs include the following components:
Stimulus control Self-control Contingency contracts Social support Careful self-monitoring
Cognitive behavior therapies (CBT) — focus on interdependence of feelings, thoughts, behavior, consequences, social context, and physiology
Weight Control: Evaluation of Cognitive-Behavioral Techniques
Efforts are somewhat successful Losing 2 pounds/ week for 20 weeks Maintenance for 2 years Programs emphasize self-direction, exercise, and
relapse prevention
Health psychologists suggest Sensible eating and exercise Rather than specific weight reduction techniques
Eating Disorders: Anorexia Nervosa DSM-IV Criteria
Self-starvation BMI chronically < 18 Intense fear of weight gain Disturbance of body image Amenorrhea for at least three months
Health Hazards of Anorexia Slowed thyroid function Heart arrhythmias Low blood pressure Dry and yellowed skin Anemia Brittle bones
Bulimia Nervosa DSM-IV criteria
At least two bulimic (binge-purge) episodes a week for at least 3 months
Lack of control over eating Behavior designed to avoid weight gain Persistent, exaggerated concern about weight
History and Demographics Strong gender bias: 10 to 1 ratio of women
to men Prevalence
Anorexia nervosa: 0.5% to 1.0% of young adult and adolescent females
Bulimia nervosa: 1.0% to 3.0%
Biological Factors in Eating Disorders
Hypothalamic-pituitary-adrenal Axis (HPA) HPA abnormalities that may promote depression
are linked with both anorexia and bulimia HPA abnormalities return to normal when disordered
eating stops
Heredity and Eating Disorders? Bulimia and identical twins (75% concordance rate) Bulimia and fraternal twins (27% rate) The chances that a young adult woman will
be diagnosed with a clinical eating disorder are much greater if she has a female relative who has anorexia
Family history of major depression, obsessive-compulsive disorder (OCD), and anxiety
Psychological Factors Competitive, semiclosed environments of
some families, athletic teams, and sororities may foster disordered eating
Families of anorexics High achieving Competitive Overprotective Intense interactions Poor conflict resolution
Psychological Factors Families of bulimia patients
Above-average incidence of alcoholism, substance abuse, obesity, and depression
Anorexic and bulimic daughters rate their relationships with their parents as disengaged, unfriendly, and even hostile
Less accepted by their parents, who are perceived as overly critical, neglectful, and poor communicators
Sociocultural View Dieting/disordered eating viewed as
responses to social roles, cultural ideals Shown photographs of ultra-thin actresses
and models, they respond with increased shame, depression, and dissatisfaction with their own bodies
Body Image and the Media Media representation of “ideal” female
weight has decreased to that of the thinnest 5% to 10% of American women
Treatment of Eating Disorders A range of treatments Behavioral treatments have been used,
from force-feeding to family therapy Restoring body weight is the first priority Drug therapy (antidepressants, appetite
suppressants, opiate antagonists) is controversial
Cognitive Behavioral Treatments Exposure-Response Prevention
A behavioral treatment of bulimia nervosa that attempts to prevent purging (and therefore reinforcement) following binge eating
How Effective Are Treatments for Eating Disorders?
Most therapies result in some short-term success, but poor long-term outcome
Cognitive behavior therapy is fairly effective as a primary prevention for binge eating in high-risk women
Some degree of disordered eating may be normative for college women; reduction of disordered eating after graduation is also normative