Lose 4 inches in 30 day. Possible?

Depends on how much of that is body fat and how much is bloat from water weight. But, you can't spot reduce. You could lose a bit of body fat and water weight, but it'd come from all over. Water weight would come off pretty quickly if you manage your sodium intake and drink enough water. Body fat takes a bit longer, but you could still lose some with a proper diet.

Very true. Spot reducing isn't going to happen. However, set your calories up to lose the maximum amount of weight possible without straying over to it being ridiculously unhealthy.

To reiterate, reduce your sodium intake to reduce water weight, and stay away from foods that will cause you to bloat. Watch your fats. Try to eat cleaner foods, that is, eat foods that don't contain alot of bacteria which will create gas in your intestinal tract and give unwanted size. You may think about eliminating dairy temporarily until you hit your goal.

If you need to be extra slim THAT particular day, there are some tricks you can google to get rid of water weight and such. Taking a shot or two is always my favorite. If it's just to be slimmer for the longer term, it's all going to come down to diet.

Unless you already have a very small body fat percentage, I believe it's completely possible to lose 4 inches in 30 days, but the only way you're going to find out is if you try and don't worry about what we think Good luck and work hard.