Smoke as in cigarettes or weed?
If cigarettes, same here, when I started smoking cigarettes and got hooked, I used it to replace my hunger, and when I'm headed to school or at work and can't grab a meal because i'm late or because there's no food available, I use cigarettes as a 'meal' . It led to me losing my appetite for any food (especially oily/fatty meats). Maybe if you watch what you eat, and start drinking more juices, water, and fruits/vegetables you'll feel better. Don't sleep when you're really tired or you may end up oversleeping. What is a routine/pattern you noticed? What you eat, how often you smoke, how busy/active you are and how often do you sleep/rest.