You see lots of "celebs" having lost stones having "hit the gym" but they then go on to say they exist on a few leaves and some water 
A woman at work has been doing 5-2 and has lost a bit over a long period but also has been doing loads of exercise classes but I'm sure that her loss would have happened with just the5-2.
I go to 2 Zumba classes and a step class each week and myself and all the other attendees look no different! I'm now starting to think my time and money would be better spent simply on a healthy diet.
I do think exercise lifts my mood but I'm unconvinced it affects weight loss.