Can I survive on only Zucchini,mushrooms,red peppers?

No. Don't eat this all day every day. The best way to lose weight is eat about 1500 calories (which is a 1000 calorie deficit for most people). To lose a pound you need to have a 3500 calorie deficit so in three and a half days you will have lost a pound of fat in a healthy way. Drink only water, and eat lean proteins such as chicken and fish. Switch to whole grains and avoid dairy, red meat, fats, and processed food. If you eat only the above diet you will become malnourished and actually gain weight.