How much weight can one loose in a month on a 1000 calorie a day diet?

A lot, I lost 7 stone in 9 months from a 1000 a day calorie diet.

WARNING, you may faint often, especially if you are an active person, you will get obsessed about calories and people will worry about you! It is not healthy, try a more moderate diet! If you won't try a moderate diet, eat plenty of veg, wholemeal bread, rice, pasta etc to fill you up for longer- avoid hunger spikes etc and try low calorie bread (such as hovis, wholegrain nimble) with high in protein fillings such as low fat pate or low fat cheese, trimmed bacon etc. (my famous 150 calorie bacon Sandwiches). use low fat spreads, 0% fat yoghurt is a good snack! Wholegrain cereal such as weetabix or shredded heat with skimmed milk for breakfast, both around 200 calories for two biscuits.