It really depends on your goals. You will lose weight very quickly if you just eat protein and vegetables. This diet is called a protein sparing modified fast and is basically the best way to lose weight quickly and without health risks. The problem is that the diet is super restrictive, bland, and can make you feel sluggish and just all around bad (some people feel great on it though...depends on the person). I personally wouldn't suggest it as it was far too intense for me and actually caused me to binge.
I would suggest you figure out your maintenance calories, subtract maybe 500-1000 depending on how strict/how fast you want to lose the weight, eat enough protein and get enough veggies and fruit in to make sure you are getting your vitamins, and fill in the rest of your calories with whatever keeps you sane and least likely to fall off the wagon. That is the best way to lose weight. If you are not losing weight or not losing it quickly enough, cut calories by a couple hundred calories and adjust from there. Pretty simple...it just takes discipline to stick to it.