One of my coworkers is currently about 296. When he was hired a couple months ago, he was over 300lb. He's still working on his weight, but he had thanked my boss and I for offering tips on eating better to, not only lose weight, but for overall better nutrition.
Exercise is actually optional - something I've learned recently. It helps, most certainly, but with work and classes sometimes I have neither the time nor energy to go jogging. So I try to maintain a healthy, eat-less-eat-right diet.