Dear Flippy, Last week I went to the doctor for a long-overdue checkup (I’m United Healthcare and figured they probably wouldn’t want to deny my claim). Overall, I’m in good health! My blood pressure is down to 170/100, and my doctor said my weight is in the 95th percentile for my height–which means lower than 95% of the population. How could he tell I’d been dieting? There’s just one problem: He said he was worried about my joints. Something about