This'll sound strange, but I think the more we disassociate exercise from weight management, the better. Too often, people's only reason for exercising is to lose or maintain their weight. I used to be like this. Up until my mid 20s, I had a really fast metabolism. I could eat anything and never gain weight. So I didn't see the point in exercising. Then I hit 25 and everything changed. I gained a lot of weight and started exercising to lose it. The problem was that once I lost the weight, I stopped exercising because, again, I thought exercise was only for weight management. Now I exercise because of all the health benefits and how great it makes me feel. The fact that it helps me maintain my weight is something I treat as a bonus, but never the primary reason for doing it. But I've sorta fallen into the trap your client has, where I worry that if I miss a workout, I'll gain weight. That's why I think it would be better to not think of exercise as something done to control weight. At least then, you won't feel guilty when you miss a workout.

You indicate that the hunger created by exercise may cause a woman to eat more and that this is a negative.  If a woman made unwise choices to satisfy that hunger I would agree.  On the other hand, if she refueled and not simply ate to satisy the hunger, wouldn't that be a positive response?  If she refueled with a proper mix of carbs and protein couldn't that be conducive to weight loss? 

I would also agree that exercise becoming an obsession is not a good scenerio.  "I'll gain weight if I miss a workout," is not a thought one should have in a healthy exercise program.