I'm slightly addicted to diet coke! i can easily drink 2-3 litres a day, how badly could this be affecting me? weight, mood swings, health?

Not healthy.: It is not healthy from a number of perspectives. First of all you are consuming far too much artificial sugar. Additionally, you are likely subjecting yourself to large amounts of caffeine which is addictive. Caffeine can make you high one minute and then bring you down the next. It is not a good idea to be drinking the amount that you are. Please consult with your doctor or a dietitian about better options for fluids. Please be aware that it is best to slowly lower the dose of caffeine because stopping suddenly can give you with sickening headaches for at least a week after suddenly stopping.

Diet Coke: Colas contain phosphoric acid which can deplete calcium in excess which in turn can cause brittel bones. Young athletes for instance were found to have curious fractures that were found to be do to excess diet soda. Also the sweetness of the artificial sweetener can cause problems for diabetics reportedly and can also influence sugar metabolism. Many articles of late have addressed this issue.