Hello and welcome Mel! As for your question on Crystal light, it is a wiser thing to drink plain water or if you want, water with a twist of lemon or lime to give a different flavour. Crystal Light contains aspartame and can literally throw you out of ketosis. I say can because some people are very sensitive to sugar substitutes as the body's chemical reactions treat it as if it was sugar. Be very careful about drinking anything with aspartame, nutrisweet, Splenda, or any other sugar substitute. Hope this helps you in some way, and please feel free to join us on the daily thread so we get to know you!