27/11/2017
Obesity
A. General characteristics
1. BMI ≥30 kg/m2
2. About one-third of US population is obese (increasing prevalence in adults, adolescents, and children)
3. Obesity is associated with an increased risk of hypertension, dyslipidemia, diabetes mellitus, cardiovascular disease, and osteoarthritis.
B. Causes
1. Result of chronic mismatches in energy balance (energy intake > energy expenditure )
2. Energy balance determined by several variables, including metabolic rate,
appetite, diet, and physical activity.
3. These factors that determine energy balance are influenced by both genetic traits
and environmental behaviors (excessive food intake, decreased physical activity.)
4. Drug-induced (less common)—glucocorticoids, antipsychotics, antidepressants,
oral hypoglycemics, and antiepileptics
5. Neuroendocrine disorders such as Cushing syndrome and polycystic ovarian syndrome (PCOS)
C. Diagnosis
1. All adults should be screened by measuring height, weight, and calculating body
mass index (BMI)
2. BMI = body weight (kg)/height2
(meters)
3. Overweight and obese patient should be further screened with waist circumference
to assess abdominal obesity.
4. Waist circumference of ≥40 in in men and ≥35 in in women is considered elevated
and corresponds with an increased cardiometabolic risk.
5. Patients with abdominal obesity are at increased risk for heart disease, diabetes,
hypertension, dyslipidemia, and nonalcoholic fatty liver disease.
D. Treatment
1. The main treatment for obesity is dieting and physical exercise.
2. Medications if dieting and physical exercise fail. Orlistat (pancreatic lipase inhibitor), lorcaserin (selective 5-HT2C receptor agonist), and combination phentermine
and topiramate (exact mechanism of action unknown), have shown some benefit.
3. Bariatric surgery remains the most effective treatment for obesity. It has been
associated with long-term weight loss, improvement in obesity-related complications, and decreased mortality.
4. Bariatric surgery should only be attempted in patients with a BMI of 40 kg/m2
or
greater who have failed a sufficient exercise and diet regimen (regardless of use
of obesity medication) and who present with obesity-related comorbid conditions
(such as hypertension, diabetes mellitus, and hyperlipidemia).