Body Mass Index (BMI) is one number that is supposed to spell out quite a bit about your health. Take your height and weight, do some figuring according to the BMI formula, and boom! You've got a number that carries a lot of weight with doctors, nutritionists and other health experts. But how much stock should you really put in this value?

The BMI system has been used since around the 1830s as an indicator for health, says Brandon Mitchell, a health educator at Allegiance Health's Department for Prevention and Community Health.

Courtesy photoNILADRI BASU

Ask the expert -- According to Niladri Basu, an assistant professor of environmental health sciences at the University of Michigan School of Public Health, there is scientific evidence that BPA can leach from bottles into water -- even at room temperature. And, when pressed, he says he would not want his children to drink out of bottles that use BPA.