The new drill sergeant in the war on flab is Barry Jay of Barry’s Bootcamp in West Hollywood. Inspired by the military’s basic training, Jay makes clients like Sandra Bullock, Rebecca Gayheart, Chris Noth, and the occasional studio exec be all they can be with 30 minutes of high-speed treadmill running followed by 30 minutes of body sculpting and hundreds of push-ups. Enlistees in the super-rigorous Academy series sweat it out five days a week, four weeks in a row. Lazybones who oversleep face a wake-up call from the entire class. ”Some people come in here because they heard about me and they want me to push them,” says Jay, a former entertainment publicist from New York City who’s worked for Bill Cosby and Roseanne. ”Others are sarcastic and tell their friends it doesn’t work. But I’m not in here to be extra nice or let you off the hook.” But don’t let his tough-guy act fool you. If you upchuck during the class (hey, this ain’t for sissies!), he does give you a free T-shirt. Word is Fred Savage was thisclose to sporting the gym’s logo across his chest.