In relation to Emsie's post one of my mums friends lost alot of weight on a diet (can't remember which one) over the course of a year and kept on feeling ill alot of the time. The doctor basically said that dieting puts a strain on your body and you're more likely to pick up colds etc when you're loosing weight. A bit like when you're grieving, or generally feeling run down etc. However I don't think that really relates to feeling light headed.