Can I lose weight from stomach fast without exercise?
I believe your question is whether you can lose abdominal fat (fat in the stomach region) without exercising. Yes, it is possible to lose abdominal fat or any body fat by creating a calorie deficit. Or in simple language, by eating less or taking lesser number of calories than you spend. But that is not a healthy way to lose fat.
When you lose weight by eating less, the body starts spending from its reserve. You not only lose fat but you would lose some precious muscle too. To prevent loss of muscle you have to eat a balanced diet (including sufficient protein) and exercise so that a continuous demand is placed on the muscle mass of the body and it is preserved. If you do not exercise, the body treats the unused muscle also as expendable source along with body fat! The lost muscle can't be regained later.