What Dosage Of Galvus Should Be Taken For Losing Body Weight?

I am hana, a female , 31 years old 171cm weighing 100 kg. I am seeking to loose weight. Had a gastric bypass 3 years ago. Lost only 27 kg and still have to struggle with 20 kg. I am not suffering from any blood sugar tyow problems. I want to use galvus to help me in reducing my weight. I dont know the dosage that I should intake while dieting. Thank you in advance for your help