Obesity

Obesity 150 150 Tony Guo

Obesity

  • Classifications of Body Weight and Obesity
    • Patient assessment
      • BMI is calculated by dividing a person’s weight (kg) by the square of the height (m2).
        • BMI less than 18.5 kg/m2 is considered underweight
        • BMI of 18.5 to 24.9 kg/m2 is considered normal weight
        • BMI of 25 to 29.9 kg/m2 is considered overweight
        • BMI above 30 kg/m2 is considered obese
        • BMI greater than 40 kg/m2 is extreme obesity
      • Waist circumference
        • People with visceral fat and truncal obesity are at an increased risk for cardiovascular disease and metabolic syndrome
          • Men >40” waist
          • Women >35” waist
      • Waist-to-Hip Ratio
        • Method of describing distribution of subcutaneous and visceral adipose tissue
        • Waist measurement/hip measurement
          • WHR <0.8 optimal
          • WHR >0.8 at risk for health complications
      • Body shape
        • Apple-shaped body
          • Fat located primarily in abdominal area
          • Android obesity
        • Pear-shaped body
          • Fat located primarily in upper legs
          • Gynoid obesity

 

Relationship between Body shape and Health risks
Body Shape Characteristics Health Risks
Gynoid (pear) Fat mainly located in the upper legs Osteoporosis
Has a better prognosis but difficult to treat Varicose veins
Cellulite
Subcutaneous fat traps and stores dietary fat
Trapped fatty acids stored as triglycerides
Android (apple)  Fat primarily located in abdominal area Heart disease
Fat also distributed over upper body (neck, arms, shoulders) Diabetes mellitus
Greater risk for obesity-related complications Breast cancer
Endometrial cancer
Visceral fat more active, causing decreased insulin sensitivity
Increased triglycerides
Decreased HDL cholesterol
Increased BP
Increased free fatty acid release into blood

 

  • Primary obesity 
    • Excess caloric intake for body’s metabolic demands
  • Secondary obesity
    • Chromosomal and congenital anomalies
    • Metabolic problems
    • CNS lesions and disorders
    • Drugs (corticosteroids, antipsychotics)
  • Epidemiology of obesity
    • About 34% of adults in U.S. are obese
    • 1 in 10 children become obese as early as ages 2 to 5
    • Obesity rates are highest
      • In the South
      • Among African Americans and Hispanics
      • Among lower income and less educated
    • The processes leading to and sustaining obese state are complex
      • Body weight beyond physical requirements
      • Abnormal increase and accumulation of fat cells
    • Increase in number (hyperplasia) and size (hypertrophy) of adipocytes
      • Large increases in lipid storage
      • Preadipocytes are triggered to become adipocytes once storage of existing fat cells is exceeded
  • Genetic/Biologic basis
    • Strong evidence of significant genetic/biologic susceptibility factors that are highly influenced by environmental and psychosocial factors
      • Factors can be considered individually but in reality they are interrelated
    • Research has identified several genes linked to obesity
      • Energy thrifty genes
      • Strong link between FTO gene and BMI
        • People with 2 copies of a certain allele at the FTO gene weigh 7-8 lbs. more and have greater risk of obesity
    • Research focused on processes that control 
      • Eating behavior
      • Energy metabolism
      • Body fat metabolism
    • Hormones and peptides in obesity
Where Produced Normal Function Alteration in Obesity
Anorexins (Suppress Appetite) 

Leptin

Adipocytes Suppresses appetite and hunger

Regulates eating behavior

Obesity is associated with high levels. Leptin resistance develops; thus obese people may lose the effect of appetite suppression.
Insulin
Pancreas  Decreases appetite  Increased insulin secretion which stimulates increased liver synthesis of triglycerides and decreased HDL production
Peptide YY
Colon  Inhibits appetite by slowing GI motility and gastric emptying Circulating levels are decreased. Decreased release after eating
Cholecystokinin
Small intestine Inhibits gastric emptying 

Sends satiety signals to hypothalamus

Unknown role
Glucagon-Like Peptide-1 (GLP-1)
Small intestine Stimulates insulin secretion from pancreas

Increases satiety (mediated by GLP-1 receptors in brain)

Unknown role
Orexins (Stimulate Appetite)

Neuropeptide Y

Hypothalamus Stimulates appetite  Imbalance causes increased appetite
Ghrelin
Stomach (primarily) Stimulates appetite increase after food deprivation

Decrease In response to food in the stomach

Normal postprandial decline does not occur, which can lead to increased appetite and overeating

 

  • Cultural and ethnic health disparities
    • African Americans and Hispanics have a higher prevalence of obesity than whites.
    • Among women, African Americans have the highest prevalence of being overweight or obese, and 15% have extreme obesity.
    • Among men, Hispanics have the highest prevalence of being overweight or obese.
    • African American and Hispanic women with low incomes have the greatest likelihood of being overweight when compared with other socioeconomic groups.
    • Native Americans have a higher prevalence of being overweight than the general population.
    • Among Native Americans ages 45 to 74, more than 30% of women are overweight and more than 40% are obese.
    • Asian Americans have the lowest prevalence of being overweight and obese compared with the general population
  • Health risks associated with obesity
    • Psychosocial
      • Depression
      • Low self-esteem
      • Risk of suicide
      • Discrimination
      • Social isolation
    • Endocrine/Metabolic
      • Type 2 diabetes mellitus
      • Metabolic syndrome
      • Polycystic ovary syndrome
    • Respiratory
      • Obesity hypoventilation syndrome
      • Sleep apnea
      • Asthma
      • Pulmonary hypertension
      • Exercise intolerance
    • Reproductive (Women)
      • Menstrual irregularities
      • Infertility
      • Gestational diabetes
    • Reproductive (Men)
      • Hypogonadism
      • Gynecomastia
      • Sexual dysfunction
    • Musculoskeletal
      • Osteoarthritis
      • Impaired mobility and flexibility
      • Gout
      • Lumbar disk disease
      • Chronic low back pain
    • Cardiovascular
      • Hyperlipidemia
      • Sudden cardiac death
      • Right-sided heart failure
      • Left ventricular hypertrophy
      • Coronary artery disease
      • Deep venous thrombosis
      • Atrial fibrillation
      • Hypertension
      • Cardiomyopathy
      • Venous stasis
      • Varicose veins
    • Gastrointestinal
      • Nonalcoholic steatohepatitis (NASH)
      • Gallstones
      • Gastroesophageal reflux disease (GERD)
    • Genitourinary
      • Kidney cancer
      • Chronic kidney disease
      • Stress incontinence
    • Cancer
      • Esophagus, pancreas, thyroid, colorectal, and gallbladder cancer (both genders)
      • Endometrial, breast, and ovarian cancer (women)
  • Physiological regulatory mechanism
    • Two major consequences of obesity are due to
      • Increase in fat mass
      • Production of adipokines
        • Contribute to insulin resistance and atherosclerosis
        • Disrupt immune factors and predispose to certain cancers
  • Environmental factors
    • Greater access to food with poor nutritional quality
      • Common to underestimate food and caloric intake
    • Lack of physical exercise
    • Low socioeconomic status
  • Psychosocial factors
    • People use food for many reasons
      • Associations begin in childhood
      • Sense of satiety can be altered
      • Mindless eating
      • Eating is social and often associated with pleasure and fun

 

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