Body Mass Index Classification and Health Implications

BMI Classification and Prevalence

The American Heart Association defines Body Mass Index (BMI) categories as: Underweight (BMI < 18.5 kg/m²), Normal weight (BMI 18.5-24.9 kg/m²), Overweight (BMI 25.0-29.9 kg/m²), and Obesity (BMI ≥ 30.0 kg/m²), with obesity further classified into three categories: Class 1 (mild): BMI 30.0-34.9 kg/m², Class 2 (moderate): BMI 35.0-39.9 kg/m², and Class 3 (severe): BMI ≥ 40.0 kg/m², for adults 1
The prevalence of overweight and obesity in women has increased over time, with approximately 51% of women having a BMI ≥ 25.0, indicating overweight or obesity, according to national survey data 2

Women with a BMI of 30 to 39.9 have a higher rate of cardiovascular events (9.97 per 1000 person-years) compared to women with a normal BMI (6.37 per 1000 person-years) 3
The relative risk of fatal cardiovascular disease is higher in obese white women than in obese African-American women compared to normal-weight women 4

Waist circumference is a marker of visceral adiposity associated with increased cardiometabolic risk, and guidelines recommend risk stratification based on waist circumference (≥88 cm for women) in patients with a BMI of 25 to 34.9 5
Among Asian populations, cardiometabolic diseases occur at lower BMI levels, leading some expert guidelines to recommend lower BMI thresholds for obesity classification 5
The prevalence of obesity is higher among non-Hispanic Black women (49.6%) and Hispanic women (43.0%) compared to non-Hispanic white women (33.0%) 1