There are two sure signs you need to be aware of. If, after a little bit of time, you are not losing weight, chances are that you are not eating the right things. The only other reason for this could be a medical issue where you may have a thyroid issue or something similar.  Here is another issue. If you start to feel yourself getting weak, dizzy, sick, or rundown, you are not doing it right either. Again putting your body through extreme stress is not going to help you in the long run. It's more likely than anything to impair your progress.