I once just ate 400 cals a day because I was fixated on every lb. I gained, but it turned deadly and I sadly became anorexic. It's not the right path but I did learn a lot about diets and now want to become a dietetic but that's besides the point. The reason why your still gaining weight is because your metabolism slowed down so now your your 400 cals has turned into 4x the amount for your metabolism to digest. Slowly but surely the lbs will come off like they did for me, but then again I turned malnurished, Got 13 cavities for lack of nutrition, half the fullness of my hair and IBS. And it ruins my everyday living my life I would normally would've lived if I didn't deprive myself from food like I did. I got help from 4 different nutritionists and a eating disorder group and then had to go to many doctors for my health disorders and "Syndromes". So for the sake of your health please don't go down my path. I know it's not cheap but go to a nutritionist instead.....~Patrycja