I had gastric sleeve surgery 6 weeks ago i've lost 13kg but for the past 2 weeks i have not lost anything on the scale i'm desperate to lose another 25kg why has my weight plateau my diet is very healthy ?

Follow the math: One must consume fewer calories than she uses or else she will not lose any weight. Even if she is eating apparently small amounts of food, and moving a lot, the laws of nature do not change... meaning there will not be weight loss until the number of calories taken in to one's body is less than the number of calories burned up each day. This is always true for "normal, healthy people."