A lot of the low fat foods are not reduced in calories, so you have to watch that. And you have to make sure you don't use the fact that something is low fat as an excuse to eat more of it. We found in studies in our lab that when we served people a first course before lunch that was labeled low fat, they ate more calories over the rest of the day, than when they were served a course labeled high fat. We can play mind games with ourselves, and we have to watch that. I think it's basically more satisfying, rather than restricting things by saying I have to go low fat, it's more positive to add things to your diet, increase the amounts of fruits and vegetables.
Exercise is critical.
For one thing it shows that you've made a commitment to lifestyle changes that are going to improve your health. Regular physical activity improves your mood, it helps build muscle, which burns more calories generally improves your flexibility and well being. So it's key. There's some studies that indicate exercise helps you get in touch with your hunger and satiety. I think people worry that exercising will make them eat more and make them hungrier, but research hasn't shown that to be the case.