Why would you do that?, of course it will make you worse, lack of vitamins and minerals??.
If you say you take a vitamin tablet then that isn't enough either, they are supplements that are meant to be taken as part of a good diet. You should try and get as many vitamins/minerals from as much food as you can.
Eat properly, no junk ( apart from the odd treat ) and exercise if nothing else it will help your well being.