Nadler, as a Last Resort, Sheds Weight by Surgery
Rep Jerrold Nadler, Manhattan Democrat, loses 61 pounds after undergoing stomach-reduction surgery in August; has struggled for decades with health-threatening obesity and futile dieting; number of bariatric operations has gone from 20,000 in 1995 to 60,000 in 2000 despite pain, risk and changes in eating habits that operation entails; photos; drawing (M)