What was the problem really? Was it the theroid? (gland problems are usually the main suspect for bad metabolism) or was it just bad eating habits?? Im really curious at the cause.
Remember that this will be a majority water weight and that it will come back almost immediately if you start eating carbs again. It is common for people to see these amazing losses when beginning and then it slows down to as little as 1kg/2lb per week and they lose heart and stop. Do not let this happen to you. I find it best, although difficult, to not be constantly weighing yourself. Aim for once a week at most, perhaps on a certain weekday morning, first thing after a bathroom visit. The longer you take between weighing yourself, the more you will avoid your results being skewed by natural fluctuations. Also take some photos for before and after comparisons, they can be great motivators when you can SEE the results. It is not uncommon to have your weight loss plateau but still lose inches, especially if working out.