Well Bobert, I agree that your answer to the P-Vine is the correct one and you should stick to it. In fact, the Body Mass Index currently favored by the medical folks doesn't consider a 5'6" woman overweight until she reaches 155 pounds, and Marilyn Monroe was 5'6" and weighed 150 lbs (eat your heart out Twiggy, Kate Moss et.al.). However, you can tell her that a female mudcatter who is her height and has been up and down the scales a few times finds that her waist changes about an inch with each 10 pounds she gains or loses. This is a very loose rule of thumb, and varies considerably depending on the amount of time I spend at my computer vs the amount of time I can spend in the hills with my husband and/or dog. But it should give her a rough guide.