Is there any side effects to starving yourself? like only drinking water and chewing gum but no food?

Of course: Any crash diet is potentially dangerous as chemical and mineral levels in your system can become abnormal and cause heart problems. What's the point? When you go back to eating the way you did before, you will simply gain the weight back. As you starve, you lose muscle as well as fat weight, you don't want that. A balanced diet, lower in calories, increased exercise, is the right choice.