Celebrities have a lot of stress when it comes to looking great, especially when you know that hundreds of cameras are going to be taking pictures of you from every possible angle. The pressure to look great is actually a key component to why they look good in the first place.
While pressure can very well create stress which will help to increase your cortisol (fat-adding hormone), it actually forces them to work with specific goals in mind to get the bodies they're looking for. That's the number one secret behind a celebrities body. They have a specific goal and a specific deadline to accomplishing this goal. So step one to getting a body worthy of the limelight is to set a realistic goal and have a realistic deadline for reaching that goal.