Ahh, it sure is lovely when a man realises how horrible water retention can be to us ladies! Haha, sorry, but I had to say

I dealt with this last week.
7lbs is a large amount for the span of one week, I vote water retention as well. I also think your not eating enough in the morning, you should incorporate a good balance of healthy fats, complex carbs, and lean protein.
I second weight training, it's amazing how it transforms your body. You build muscle which in turn benefits you even when your not working out. It raises your resting metabolic rate so your burning more calories afterwards as well. It also plays a big factor in body composition as well.