Age Adjusted Obesity Rates

From CDC NHANES Study

Pathways to obesity• Multiple factors

– Overeating– Fat intake (“cafeteria” diet)– Alcohol intake– Inactivity (10% get regular exercise)– Metabolic issues– Genetics “Thrifty genome”– Combinations of above

• Overweight and obesity result from an energy imbalance– Weight Gain:

Calories Consumed > Calories Used– Weight Loss:

Calories Consumed < Calories Used– No Weight Change:

Calories Consumed = Calories Used

Calories Used • Physical activity is any bodily movement produced by skeletal

muscles that results in an expenditure of energy with a range of activities such as

• Occupational workCarpentry, construction work, waiting tables, farming

• Household choresWashing floors or windows, gardening or yard work

• Leisure time activitiesWalking, skating, biking, swimming, playing Frisbee, dancing Structured sports or exercise Softball, tennis, football, aerobics

Eating environment • In America, a changing environment has broadened

food options and eating habits – greater selection of products– pre-packaged foods– fast food restaurants– soft drinks

• Portion size has also increased

Portion DistortionIn the last 50 years we’ve seen …..

– Plates– Drinks– Cup Holders– Servings– Ourselves

……..ALL GET LARGER!

Genetics• “thrifty genotype” hypothesis : the same genes that

helped our ancestors survive occasional famines – tendency to overeat – tendency to be sedentary – easily stimulated capacity to store body fat

• Evidence of genetic influence– differences among family members, twins, and adoptees – some genes at higher frequencies among the obese

• Many different genes contribute to the effects – fat mass and obesity-associated gene might be responsible for

up to 22% of all cases – gene for Leptin in rare cases

Genetics, Metabolic Rate, and Body Weight

• Genetics- heritability of .40 to .70 percent for obesity

• Metabolic– Pima Indians who have an unusually high rate of

obesity – This could be the FTO gene

• Fat mass and obesity-associated protein

– inked to a thrifty metabolism that allowed them to metabolize food more efficiently

– variations in their mitochondrial DNA

Figure 13.19 Why Losing Weight Is So Difficult

Inherited Obesity: Both of these mice are (ob/ob)

•This mouse was treated with leptin

Leptin Treatment

Relation among weight, leptin, NPY, and eating.

0rdinarily, high levels of body fat produce leptin, which inhibits eating. Obese mice fail to produce leptin. Obese humans produce leptin but fail to respond to it.

Obesity Treatments– Dieting to reduce caloric intake – Surgery

• Gastric stapling reduces stomach volume– Compensation (stomach stretch after stapling)

• Intestinal bypass reduces food absorption– Diarrhea and flatulence are problematic– Bacterial overgrowth and vitamin deficiencies

– Pharmacological:• Suppression of appetite

– Herbal preparations that that contain ephedrine– Amphetamines or Cocaine– Canabinoid antagonists producing an anti-high

• Blockade of fat absorption (Xenical)• Drug effecting hypothalamus based on

– Leptin– Ghrelin– PYY

Body Fat Stores Are Tightly Regulated, Even after Surgical Removal of Fat

Anorexia Nervosa & Bulimia• Anorexia is the decreased sensation of appetite • Anorexia nervosa

– an irrational fear of becoming obese– a preoccupation or with their weight and food– a distorted body-image– persistently starve themselves and deny their appetites– do not usually lose their appetites

• Bulimia– illness in which a person binges on food– has regular episodes of overeating– feels a loss of control– Various methods -- such as vomiting or laxative abuse -- to

prevent weight gain.

Fig 13.25

Social and Personality FactorsLow self-esteem and unhappiness

•Controlling family members

•perfectionists and overachievers

•“good” daughters who do what they’re told

•excel in everything they do

•focus on pleasing others

•Emphasis on physical appearance

•Participation in an activity that demands slenderness

•Ballet

•Gymnastics

•modeling

•Anxiety and/or Stressful events

•onset of puberty, a breakup, or going away to school

Early Onset

Major Eating Abnormalities Have Their Origins in Childhood

42% of girls age 6 to 9: “want to be thinner”

81% of girls age 10: “afraid of being fat”

15% of young women heading to college already have substantially disordered eating attitudes and behaviors

Pre-teen years (to lose weight):• 50% exercise• 50% diet• 5% take diet pills or laxatives• Many smoke

Sources: Mintz LB, Betz, NE. Prevalence and correlates of eating disordered behaviors among undergraduate women. Journal of Counseling Psychology. 1988;35:463-471.Collins ME. Body figure perceptions and preferences among pre-adolescent children. International Journal of Eating Disorders. 1991;10:199-208.Mellin L, McNutt S, Hu Y, Schreiber GB, Crawford P, Obarzanek E. A longitudinal study of the dietary practices of black and white girls 9 and 10 years old at enrollment: The NHLBI growth and health study. Journal of Adolescent Health. 1997;20:27-37.Serdula MK, Collins E, Williamson DF, Anda RF, Pamuk E, Byers TE. Weight control practices of US adolescents and adults. Annals of Internal Medicine. 1993;119:667-671.Picard CL. The level of competition as a factor for the development of eating disorders in female collegiate athletes. Journal of Youth & Adolescence. 1999;28:583-594.Gustafson-Larson AM, Terry RD. Weight-related behaviors and concerns of fourth-grade children. Journal of American Dietetic Association. 1992;92:818-822.

85% of families are “sometimes” or “often” on a diet

Genetic Factors May Predispose People to Eating Disorders

• Increased risk of anorexia nervosa among first-degree biological relatives of individuals with the disorder

• Increased risk of mood disorders among first-degree biological relatives of people with anorexia, particularly the binge-eating/purging type.

• Twin studies– concordant rates for monozygotic twins is significantly higher than those for

dizygotic twins.

• Mothers who are overly concerned about their daughter’s weight and physical attractiveness might cause increase risk for development of eating disorders.

• Girls with eating disorders often have brothers and a father who are overly critical of their weight.

Comorbitiy with Anxiety

Eating Disorders Rarely Appear Independent of Other Psychiatric Conditions

Anorexia Nervosa

• .5% lifetime prevalence in women (.05% men)

Bulimia Nervosa

• 1%–3% lifetime prevalence in women (.01–.03% men)

Women with Anorexia or Bulimia

• 42%: one or more childhood anxiety disorders

• 23%: Obsessive Compulsive Disorder

• 30%: abuse alcohol or drugs

• 86%: battle depression

Sources: Lamberg L. Advances in eating disorders offer food for thought. JAMA. 2003;290:1437-1442.Study Reveals Childhood Vulnerabilities that May Lead to Eating Disorders. Press Release, December 1, 2004. National Eating Disorders Association. Available at: www.nationaleatingdisorders.org/p.asp?WebPage_ID=774. Accessed February 22, 2005.

Study of 246 Women with an Eating Disorder

• 30%: attempted suicide

• 4.5%: died

Multiple factors

Eating Disorders Aren’t Completely Understood, But We Think the Causes are Multi-factorial

“We think genes load the gun by creating behavioral susceptibility such as perfectionism or the drive for thinness. Environment then pulls the trigger.”

– Walter H. Kaye, M.D.University of Pittsburgh, Western Psychiatric Institute and Clinic

Genetics

Environment

• Women’s magazines: 10 times more ads promoting weight loss than men’s magazines

• Miss America: Weight has declined 12% since 1920sSources: Lamberg L. Advances in eating disorders offer food for thought. JAMA. 2003;290:1437-1442.Andersen AE, DiDomenico L. Diet vs. shape content of popular male and female magazines: a dose-response relationship to the incidence of eating disorders? International Journal of Eating Disorders.1992;11:283-287.Rubinstein S, Caballero B. Is Miss America an undernourished role model? JAMA. 2000;283:1569.

The Cutting Edge: A Rumbling in the Belly

Two and a half to five pounds of normal or gut flora (microbes) provide beneficial actions.

Each of us possesses a distinct bacterial enterotype—a personal combination of different species of normal flora.

The Cutting Edge: A Rumbling in the Belly

Some diseases and antibiotic treatments can drastically alter the balance of our gut flora, resulting in pathogens being able to become established.

Fecal transplantation is a treatment used effectively to restore necessary gut flora.