What is the average Body Mass Index (BMI) for women?

Average BMI for Women in the United States

The average BMI for women in the United States falls within the normal weight range of 18.5-24.9 kg/m², with a median BMI of approximately 21.5 kg/m² for healthy women. 1

BMI Classification for Adults

Body Mass Index (BMI) is calculated as weight in kilograms divided by height in meters squared and is commonly used to classify weight status:

• Underweight: BMI < 18.5 kg/m² 2
• Normal or acceptable weight: BMI 18.5-24.9 kg/m² 2
• Overweight: BMI 25.0-29.9 kg/m² 2
• Obesity: 2
  • Class 1 (mild): BMI 30.0-34.9 kg/m²
  • Class 2 (moderate): BMI 35.0-39.9 kg/m²
  • Class 3 (severe): BMI ≥ 40.0 kg/m²

Gender Differences in BMI Distribution

Research shows significant differences between healthy men and women in BMI distribution:

• Healthy women have a median BMI of approximately 21.5 kg/m², while healthy men have a median BMI of approximately 24.5 kg/m² 1
• The BMI distribution for healthy women is shifted to the left compared to men and is more skewed 1
• The range of BMI values that includes 90% of healthy women is approximately 18-30 kg/m² 1

Prevalence of Overweight and Obesity in Women

According to national survey data:

• Approximately 43.6% of adult women in the United States have a BMI between 19.0 and 25.0 3
• About 50.7% of women have a BMI ≥ 25.0, indicating overweight or obesity 3
• The prevalence of overweight and obesity has increased over time, with NHANES III showing that the combined prevalence of overweight and obesity in women was about 51%, compared to 41% in NHANES II 2

Health Implications of BMI in Women

• Women with BMI values within the normal range but at the higher end (23.0-24.9 kg/m²) have an increased risk of coronary heart disease compared to women with lower BMI values within the normal range 4
• Even modest weight gains after 18 years of age are associated with increased risk of coronary heart disease in women 4
• Cardiovascular event rates were 9.97 per 1000 person-years in women with a BMI of 30 to 39.9 compared with 6.37 per 1000 person-years in women with a normal BMI 2
• The relative risk of fatal cardiovascular disease is higher in obese white women than in obese African-American women compared with normal-weight women 2

Waist Circumference as a Complementary Measure

• Waist circumference is a marker of visceral adiposity associated with increased cardiometabolic risk 2
• Guidelines recommend risk stratification based on waist circumference (≥88 cm for women) in patients with a BMI of 25 to 34.9 2
• This measurement helps identify women who may have higher health risks despite having a BMI in the normal or overweight range 2

Considerations for Specific Populations

• Among Asian populations, cardiometabolic diseases occur at lower BMI levels, leading some expert guidelines to recommend lower BMI thresholds for obesity classification 2
• 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%) 2

While BMI is a useful screening tool at the population level, it's important to recognize that it doesn't directly measure body fat or account for individual differences in body composition and risk factors 2.