So, my experience is that losing weight necessitates allowing your training to become somewhat inconsistent. So let's say you can normally manage 4 days of hard workouts a week, when dieting you may only get 1 or 2 good workouts in weekly. As your time in zone decreases, in order to maintain as much of your power as possible you have to make those days really count. Running a calorie deficit is hard enough; running a calorie deficit while restricting carbs seems like a bad idea if you're going to try to maintain ftp. You'll more than likely lose weight, but I'm pretty positive you'll also lose a lot of power.