If you eliminate too many carbs, your brain gets angry, since it needs carbs to function. Lot of people report being fatigued due to the Atkin's diet (which apparently reduces carbs). If this is similar and you go too overboard, then you can expect the same.
Furthermore, Dave pointed out that you need to exercise. If you want to exercise, you need carbs. It'll be hard for you to do much if you don't have the fuel for it.
Lastly, you have to look at calories. Lots of foods high in carbs are actually high in calories. Things like junk food, sodas, etc. If you eliminate THOSE carbs, you are eliminating a boatload of calories, which IS good.
I'm on a diet myself, but mine is as simple as reducing all junk food as much as possible. I noticed that tiny amounts of junk food have huge amounts of calories. If you stay away from those, you eliminate a lot of calories from your diet in a safe way.