Mr.Arhan your doctor must have asked for certain other blood tests also,and if there is any evidence of TB therein...then he has started your ATT and as a result of positive response ,you might be gaining weight.
For weight loss , you can restrict your
sugar,carbohydrate and fat intake also can do regular light physical activity.
Next Steps
Post all you investigations and test report.
Health Tips
If you have been diagnosed as a case of Abdominal TB, take the treatment properly.