Is it possible to gain weight at the begging of a low carb diet?

I have been following the Atkins diet for 3 days now, and i know that isn't long enough to show results but i don't think i should be feeling any bigger either. is it possible that my body still isn't used to it so its taking in more fat or something. Some one please give me advice quick.... or ill get discouraged and give up too easily lol