The first time I heard someone claim that exercise does not help you lose weight, I scoffed at it. But more and more researchers are concluding that the role of exercise in weight loss has been wildly overstated. The basic problem: exercise makes you hungry. There is an interesting article in Time Magazine this week on this very subject. Gary Taubes has an extended discussion of the exercise/weight loss fallacy in his book, Why We Get Fat, and this Time Magazine article essentially makes all of the same arguments Taubes has made.
So why is the belief so ingrained in the public mind that exercise leads to weight loss? Because lean people are more active than fat people, therefore, it MUST be the exercise that is making the difference. This is a fallacy, similar to the belief that if we put books in more homes, we will produce smarter children. Children who read do indeed become smarter and are more likely to be middle class, but it is not merely the presence of books in the home that leads to this. It's because those homes that have a lot of books in them have parents and children who actually read the books. Giving a book (or many books) to someone who doesn't read will not make a person one whit smarter.
There are many good reasons to exercise, but apparently, weight loss is not one of them. Another thing on which Weight Watchers has misled me.