No matter what caused you the weight loss as in what diet/exercise etc. if you do not continue that pattern you will gain everything back eventually.
i went on ww before its a great program i lost 10 pds in 2 weeks , but i always come off of it when i get where i want to be trhan gain it back ,lol i really need to go back on it i need to lose 15 now , my sister and brother in law are on it they are doing great. congrats hang in there its a great program