Skip to content

Obesity

BASICS

Description

  • Complex, multifactorial disease with excess adipose tissue impairing health
  • Quantified by BMI ≥30 kg/m² in adults
  • Overweight: BMI 25–29.9 kg/m²
  • Obesity Class 1: BMI 30–34.9 kg/m²
  • Obesity Class 2: BMI 35–39.9 kg/m²
  • Obesity Class 3 (severe): BMI ≥40 kg/m²
  • Abdominal obesity = higher morbidity/mortality risk
  • Associated with eating disorders

Geriatric Considerations

  • Aging: sarcopenia, decreased bone mineral density, more visceral fat

EPIDEMIOLOGY

  • Adults: 42% of US adults obese; highest in ages 40–59
  • Children: 20% US children/adolescents (2–19 yrs)
  • Pediatrics:
  • Overweight: BMI ≥85th–<95th percentile (age/sex)
  • Obesity: BMI ≥95th percentile
  • Severe Obesity:
    • Class II: ≥120–139% of 95th percentile
    • Class III: ≥140% of 95th percentile
  • 1 in 6 US children obese before school age
  • Childhood obesity strongly predicts adult obesity

ETIOLOGY AND PATHOPHYSIOLOGY

  • Multifactorial: genetics, environment, behavior, psychosocial
  • Adipocyte hormones:
  • Adiponectin (improves insulin sensitivity)
  • Leptin (absence → severe obesity)
  • Obesity alters neuronal satiety signaling; leads to inflammation
  • Genetic syndromes: Prader-Willi, Bardet-Biedl (rare)

RISK FACTORS

  • Parental obesity
  • Sedentary lifestyle
  • Poor nutrition (calorie-dense foods, limited fresh produce)
  • Mental illness, stress

GENERAL PREVENTION

  • Regular physical activity: ≥150 min moderate exercise/week
  • Balanced diet, portion control, limit sugar-sweetened/processed foods
  • Early counseling in children/young adults

COMMONLY ASSOCIATED CONDITIONS

  • Metabolic: Type 2 DM, HTN, hyperlipidemia, NAFLD, PCOS
  • CV: CAD, CHF
  • Others: OSA, osteoarthritis, mood disorders (anxiety, depression)

DIAGNOSIS

History

  • Assess diet, exercise, readiness to change, prior weight loss, social support
  • Screen for eating disorders, stressors

Physical Exam

  • Physical Activity Vital Sign (≥150 min/week)
  • Waist circumference:
  • Male: >40" (102 cm)
  • Female: >35" (88 cm)
  • More predictive than BMI in elderly
  • Signs: large neck, acanthosis nigricans, striae

Differential Diagnosis

  • Cushing syndrome, hypothyroidism, psychiatric disorders

Diagnostic Tests

  • Fasting glucose, HbA1c, lipid panel, thyroid function, LFTs
  • Screen for OSA (sleep study) if fatigue present

TREATMENT

General Measures

  • Assess motivation, goals, interest in meds/surgery, dietary/activity habits
  • Goal: Sustain ≥5% body weight loss
  • Behavioral interventions = 1st line (per USPSTF)
  • Treat obesity-related comorbidities

Medication

  • After 3–6 months of lifestyle intervention alone
  • Indications:
  • BMI ≥30
  • BMI ≥27 + comorbidities
  • Long-term (FDA-approved):
  • Liraglutide (GLP-1 agonist): for DM/CVD, ≥12 yrs old
  • Semaglutide (GLP-1 agonist): highly effective
  • Phentermine/topiramate: oral, misuse potential, fetal toxicity
  • Orlistat: reduces fat absorption, ≥12 yrs old, GI side effects
  • Naltrexone/bupropion: opioid antagonist + antidepressant
  • Superabsorbent hydrogel (Plenity): oral, FDA device
  • Short-term: (sympathomimetics; e.g., phentermine, diethylpropion)
  • For <12 weeks; watch for CV side effects

Additional Therapies

  • Physical activity: adds to diet-induced weight loss (dose-response)
  • CBT: reduced-calorie diet + increased physical activity + behavior change; best in-person, high-intensity (≥14 sessions/6 months)
  • Surgery:
  • Consider for BMI ≥35 + comorbidities or BMI ≥40
  • Types: gastric bypass, sleeve gastrectomy, banding, etc.

ONGOING CARE

Follow-Up

  • Reassess goals regularly; long-term approach
  • Change plan if <5% weight loss in 3–4 months

Diet

  • Calorie reduction:
  • Women: 1200–1500 kcal/day
  • Men: 1500–1800 kcal/day
  • Net deficit ~500 kcal/day = ~1 lb/week loss
  • Mediterranean or DASH diets: shown to reduce CVD risk and weight

Patient Education

  • SportsMedToday: https://www.sportsmedtoday.com/exercise-prescription-va-156.htm
  • Healthy Eating: https://health.gov/sites/default/files/2021-08/DGA-FactSheet-2021-03-26-compressed.pdf

PROGNOSIS

  • Increased risk of CVD, osteoarthritis, some cancers
  • Motivation predicts successful weight loss

COMPLICATIONS

  • CVD, osteoarthritis, SCFE (children), increased cancer deaths (colon, breast, prostate, endometrial, gallbladder, liver, kidney)

ICD-10 Codes

  • E66.9 Obesity, unspecified
  • E66.3 Overweight
  • R63.5 Abnormal weight gain

Clinical Pearls

  • Obesity prevalence is increasing; most US adults overweight/obese
  • Diet + physical activity = cornerstone therapy
  • Consider surgery for BMI >40 with failed conservative tx or BMI >35 with comorbidities
  • Medication indicated if lifestyle modification fails after 3–6 months and BMI >30 or >27 with comorbidities