Body Mass Index (BMI) is a ratio of weight to height. It is a screening tool for spotting people who are more likely to develop various health problems from over or underweight, and for tracking that development in children is progressing appropriately. In adults, a BMI Between 18.5 and 25 is considered healthy. Below 18.5 is underweight. Higher than 25 is overweight; higher than 30 is obese.
In children, the BMI is expressed not only as a number, but as a percentile rank. The child or teen is plotted against other kids of the same age. A child who has a BMI greater than 85 percent of children her age is considered overweight; greater than 95 percent is considered obese. A BMI of less than 5 percent is considered underweight.
There is a very wide range of weights that are considered healthy for a given height in children and adults. Juliana’s healthy weight range is between 93 and 136 pounds. My healthy weight range is between 121 and 171 pounds.
Healthy doesn’t mean ideal for the individual. Although a BMI of 24 is considered healthy, most adults will feel better at a much lower BMI. The same is true for children–although a BMI in the 84th percentile will not technically indicate a child is overweight, that child will likely feel better at a lower BMI.