Dr.i would like to know for what reason do you think am not losing weight , after having the gastric sleeve surgery for the past 16 days?

Weight loss: Is still based on the simple equation of calories eaten minus calories burned off in a day. If you have not lost much weight, you are managing to eat the same amount of calories each day as you use. If you eat more than you use, you will gain weight. If you use more than you eat you will lose. You need to see if you have been low on using calories (and can increase activity to help) or vice vers.