++
For further information, see CMDT Part 29-04: Obesity
+++
Essentials of Diagnosis
++
Excess adipose tissue; body mass index (BMI) ≥ 30
Upper body obesity (abdomen and flank) of greater health consequence than lower body obesity (buttocks and thighs)
Many associated comorbid conditions, including type 2 diabetes mellitus, hypertension, hyperlipidemia, heart disease, stroke, and obstructive sleep apnea
+++
General Considerations
++
Quantitative evaluation involves determination of BMI
BMI accurately reflects the presence of excess adipose tissue; it is calculated by dividing measured body weight in kilograms by the height in meters squared
Normal: BMI = 18.5–24.9
Overweight: BMI = 25–29.9
Class I obesity: BMI = 30–34.9
Class II obesity: BMI = 35–39.9
Class III (extreme) obesity: BMI ≥ 40
Increased abdominal circumference (> 102 cm in men and > 88 cm in women) or high waist/hip ratios (> 1.0 in men and > 0.85 in women) have a greater risk of weight-related comorbid conditions and early death than patients with the same BMI and lower ratios
Upper body obesity (excess fat around the waist and flank) is a greater health hazard than lower body obesity (fat in the thighs and buttocks)
Visceral fat within the abdominal cavity is more hazardous to health than subcutaneous fat around the abdomen
++
US survey data indicate that almost 40% of Americans have obesity
Both genetic and environmental factors contribute to the development of obesity
Twin studies have demonstrated that genetics account for 50–90% of the variation in BMI
Only a small percentage of human obesity is thought to be due to single gene mutations
Most human obesity develops from the interactions of multiple genes, environmental factors, and behaviors
The rapid increase in obesity in the last several decades points to major roles for environmental and behavioral factors in its development
++
++
++
++