Ate (formerly YouAte) does this pretty well. It doesn't do the correlation analysis for you but it does allow you to easily log the food, whether it's on-track

Ate (formerly YouAte) does this pretty well. It doesn't do the correlation analysis for you but it does allow you to easily log the food, whether it's on-track / off-track with your goals, how you ate it, where you ate it, and how you felt.