Not to disagree, knowing nothing about health/fitness/diet etc, but...
In a year I've lost 2 and a half stone, and the only thing I've changed about my lifestyle is cycling. I now commute to work and ride on rest days too. I have an AWFUL diet, reguarly eating rubbish, at awful times of day and night, but I haven't changed that at all!
Everyone is different for some of the lucky ones it is possible to lose weight and still eat crap. In the long term there will come a crunch time when you reach an equilibrium and then you have to look at dialling the nutrition to go further. For me that was at the 12.5 - 13st mark from 16.5 stone mark. Naturally if you do no exercise then suddenly do exercise the body will respond but it will not do it forever. Everyone is different and there are loads of variables. I felt it safer to recommend eat cleaner and do exercise than eat crap and exercise a bit more vigorously. I am not an expert by any means just been on a long journey and wanted to point out what I learnt on the way.