Weight loss is one of the most common recommendations that doctors make.  How do we know if a patient should lose weight?  We usually use the Body Mass Index (BMI) which is a way to compare a patient’s weight to her height.  (For all you math geeks, it’s the weight in kilograms divided by the height in meters squared.  For all you physicists, I know the units make no sense.)  A BMI of 18.5 to 25 is considered normal.  A BMI of 25 to 30 is considered overweight, and over 30 is considered obese.  ...