Definitely not. Although it is true that many actors work long hours when on the set, (or singers on tour), they can afford to take a year long vacation so they can focus on their health. They have all the resources they could want and even a personal trainer (only one?). If I only had a house with a pool in the back with a heater, I would be swimming every single morning. Life for the average lower or middle class person isn't that easy.
Then again, there is some willpower involved, look at Kirstie Alley. She was bee-autiful 30 years ago, and she can't seem to keep the weight off now. Which reminds me to remember not to look down on overweight people after I lose my poundage. It can always come back and gluttony is often a tool to compensate for some kind of loss or stress.
Celebrities also have problems that they can't overcome, just because they're rich doesn't give them a free ride to solving them. But being rich does make it ALOT easier and I have a hard time being inspired by weight-loss celebrities.