Although I am not a smoker and I am overweight, I do have some experience of what you are going through. I have been hugely addicted to junk food, particularly chips and take-outs. I used to drink an awful lot of diet coke as well. Since giving them up and starting to get fit I also feel very tired all the time . My trick is to exercise in the morning before I get tired (there is no way I feel like exercising after a day at work!). I have porridge for breakfast, a pasta salad for lunch, and then in the afternoon when I get really tired and just want to curl up and go to sleep under my desk, I have a snack of a piece of malt loaf and some dried fruit and drink some water. This gives me the carbohydrate boost to wake up and finish my day of work.

I think the tiredness is partly a stage in the detox process, while our bodies try to rid themselves of all the bad stuff we've been eating, and partly just getting used to doing exercise. I don't know about you, but before I started exercising, I was completely sedentary, and did virtually no exercise. I'm also hoping that in time I will start to feel better, I certainly won't be able to continue for ever like this. When I have tried to do things like this in the past, I have eventually started to feel better, and even got to the point where I started to feel like superwoman. I could do anything!

Keep it up, you will get over this period, I am sure of it.