Cutting down on carbs is absolutely essential when you're eating a lot more than what your body's daily need is. When you want to lose weight, you don't deny your body of the basic carb requirement but instead up your usage by sweating it out through tonnes of cardio.
Losing weight the right way isn't rocket science but it isn't childs play either.
Cutting down on carbs will cause you to lose muscle since the body will turn to your stored proteins before the sub-glutaneous flab.
The fat comes off the face first and belly last, so it's not like you can cut carb intake for a week and expect that to have done you some good. It doesn't work like that.
Burning fat is like boiling water, you have to reach the boiling point before any fat starts dissappearing.
So if you're not starving yourself and are still giving your body ONLY it's daily requirement of carbs, there's no reason you shouldn't be fit.
People get fat because of years of eating more carbs than they burn. So its not going to come off that easily either.