Have you been to the docs and had bloods done? For thyroid etc.
Just an idea, a couple of years back when I first seriously tried to lose weight and just couldn't shift anything I went to see a nutritionalist. They tried to describe to me what my body had gone through over the last few years. Whether there is any truth in this or not I am unsure?!
I had spent years eating crap, and crap takes much more effort to process than nice healthy food. It takes more enzymes to break down, more than I had available in my digestive system, so it starts drawing them in from other organs in the body. Which is bad, so your body basically stops trying so hard to process it and just sends it on through and out the other end. Which is why fat people, don't have poo that Gillian McKeith would be proud of!
When I then started eating properly again, the food was still coming straight back out. My metabolism and digestive system had gone dormant, so I started taking digestive enzymes to aid my body until it realised it needed to be doing it itself. It made a massive difference to my weight loss. Read into it what you like? Might just be a big old coincidence, but whats the harm.
You just take two with each meal for a few weeks, dropping down to 1 with each meal and then off them. The cost about £8 for a hundred, from Holland & Barrett?!
In fact, I might just start taking them again! haha