I have happily lost 4.5st over a couple of years, down to 10st (height 5ft 7' age 51) and have done a couple of Olympic distance tri's this year.
I am determined not to let the weight return and have targeted 10st as the weight to maintain. If it starts to creep up, then I reduce intake/increase activity - it works.
However, it does occur to me that I might add some muscle mass through training and maintaining the same weight may actually be counter productive and restricting development.
Any advice on a recommended approach would be appreciated.