Ajwain, saunf along with black jeera, salt and dried ginger powder is very good for health. It helps remove flatulence in the body and provides instant relief from stomach disorders like excessive gas.There are no proven studies to show that taking ajwain and suanf will help you lose weight. However since there are harmless herbs, you can give them a try and see if indeed it really works to help you shed some flab. But nothing like eating a wholesome diet with fresh vegetables, fruits and lots and lots of exercise is going to help you. Drinking plenty of water will also help you lose weight.