Especially in the wintertime you need to watch your sugars. It can weaken your immune system a little bit more. It won't make you sick, but as I said, it can weaken that immune system. I would recommend you make sure you have some sort of protein source before you eat that sweet, that cookie. Have a nice turkey sandwich, some stew or soup.
Balance is the key.
And, remember to break things down into workable sections. Don't try to do everything at once. Make changes over period of time. They have a better chance of sticking, if blended in smartly with your everyday life. Next week, you can concentrate on drinking more water.