Calories come from carbs, fat, protein or alcohol. So if you did that, you'd still be on 600 cals and like Hannata says, it's unlikely you get the right vitamins. You could try to use the same percentages.
If you want to do something like that then weightlossresources.com is amazing. I am planning on using that to maintain my weight for some time. It tells you how many calories you can have to maintain, suggests the recommended carbs, fat, etc.
I find it easy to maintain on a low GI diet and a lot of people do that.