Understanding BMI
What BMI measures, how it is used, and its limitations.
What BMI tells you
Body Mass Index is a screening tool that uses your height and weight to estimate body fat. Developed by the National Institutes of Health (NIH), it provides a quick way to categorize weight status at the population level. Healthcare providers use BMI as one of several factors in health assessments.
BMI limitations
BMI does not directly measure body fat and has important limitations. It does not account for muscle mass (athletes may have a high BMI without excess fat), age, sex, bone density, or fat distribution. Waist circumference, body composition analysis, and other metrics provide additional context.
BMI categories (NIH)
Standard weight status categories based on the National Institutes of Health.
| Category | BMI range |
|---|---|
| Underweight | Below 18.5 |
| Normal | 18.5 – 24.9 |
| Overweight | 25 – 29.9 |
| Obesity Class I | 30 – 34.9 |
| Obesity Class II | 35 – 39.9 |
| Obesity Class III | 40 and above |
Source: National Institutes of Health (NIH) / National Heart, Lung, and Blood Institute
Beyond the number
BMI is just one number. Dose AI helps you track your complete health picture: weight trends, nutrition, medication, and how you feel day to day.
