The “healthy” body mass index (BMI) ranges from 18.5 to 24.9. However, BMI is not a one-size-fits-all concept.
BMI is a tool researchers often use to track obesity at the population level. Doctors and other healthcare professionals also use it to assess people’s health.
However, the medical community has raised concerns over using BMI as a measurement of obesity and health due to its significant limitations, particularly in assessing the health of Black and Hispanic people.
Nevertheless, some health organizations recommend that people stay within a certain BMI range to reduce their risk of disease.
BMI chart and calculator
BMI does not distinguish between male, female, and intersex bodies. It’s a formula that uses height and weight to calculate a number meant to represent a person’s body fat levels.
These numbers fit within the following categories:
BMI rangeClassificationless than 16.5severe underweightless than 18.5underweight18.5–24.9healthy weight25.0–29.9overweight30.0–34.9obesity class I 35.0–39.9obesity class II 40 or greaterobesity class IIIThis calculator can help you determine your BMI, although it isn’t specifically for cisgender women and other people assigned female at birth:
Doctors may recommend different cutoff points depending on a person’s ethnicity, muscularity, and other factors.
The relationship between race, ethnicity, and female body composition
Race and ethnicity do not determine weight, body fat distribution, proportion of muscle mass, waist circumference, or other body metrics. Every person is different.
BMI does not inherently distinguish between people of different racial or ethnic backgrounds. However, different BMI cutoffs have been developed for Asian and South Asian populations.
You’ll notice the language used to share stats and other data points is pretty binary, fluctuating between the use of “male” and “female” or “men” and “women.”
While we typically avoid language like this, specificity is key when reporting on research participants and clinical findings.
White, Black, and Hispanic
Although a BMI between 18.5 and 24.9 is associated with “healthy weight,” it doesn’t take into consideration that people differ in body shape and composition.
This means that even if two people have the same BMI, they can have very different regional body fat distribution and muscle mass.
For example, a 2015 review shows that Mexican American adults tend to have a different body fat distribution than non-Hispanic (NH) white or Black adults.
On average, Mexican American adults have more body fat and a larger waist circumference than white or Black adults.
NH Black adults tend to have a higher amount of muscle mass than white or Mexican American adults.
Studies have shown that healthcare professionals are more likely to misclassify Black women as having obesity because of their higher percentage of muscle mass.
Furthermore, researchers acknowledge that the link between BMI and mortality risk is much weaker among Black women than among white women.
Asian and South Asian
Research shows that Asian and South Asian populations have more body fat relative to their body weight than white populations and that health conditions like type 2 diabetes occur at lower BMI levels.
This has led to changes in BMI cutoffs for Asian populations. Several cutoffs have been suggested.
In one model, BMI between 23 and 24.9 is associated with overweight, and a BMI over 25 is associated with obesity.
The relationship between age, hormones, and female body composition
Older adults tend to have lower muscle mass and more fat located in their midsection than younger adults.
This is due to age-related changes in hormone levels, slowing of physical activity, and changes in torso length caused by osteoporosis.
Hormonal changes related to menopause can also affect BMI accuracy. A 2019 study of 1,329 postmenopausal participants found people with a “healthy” BMI may have overweight or obesity.
The relationship between pregnancy and female body composition
Healthcare professionals recommend that people gain a certain amount of weight during pregnancy based on their prepregnancy BMI range.
Here are the Institute of Medicine reccomendations for weight gain during single pregnancy:
Prepregnancy BMITotal weight gainRate of second and third trimester weight gainunderweight (under 18.5)28 to 40 pounds (12.5 to 18 kg)1 pound (0.51 kg) per weeknormal weight (18.5 to 24.9)25 to 35 pounds (11.5 to 16 kg)1 pound (0.42 kg) per weekoverweight (25 to 29.9)15 to 25 pounds (7 to 11.5 kg)0.6 pounds (0.28 kg) per weekobesity (30 or greater)11 to 20 pounds (5 to 9 kg) 0.5 pounds (0.22 kg) per week
Even though you can use these recommendations as helpful guidelines, it’s important to consult with a healthcare professional.
They can help you determine a healthy weight gain during pregnancy based on your specific needs and overall health.
The bottom line
Scientists and healthcare professionals are well aware that BMI has significant flaws. However, it remains an important tool for assessing public health at the population level.
Even though healthcare professionals can use BMI as a screening tool, they shouldn’t use it as a method to evaluate a person’s body fat levels or health status.
To properly assess your overall health and well-being, a healthcare professional should consider many factors, including your blood test results, diet, activity levels, and sleep habits.
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