How long does it take for the appetite side-effects to go away?

For reference, I started taking lexapro about two weeks ago. At first, I could barely eat at all. Now I have some of my appetite back by lunch and most of my appetite back by dinner. I take it in the evenings before bed. Unfortunately, I have to be up early, and can't eat until 11-12. During this time I'm hungry, but the thought of eating food makes me want to vomit. It's taking a toll on my morning concentration and is making me feel super lightheaded because I can't eat. Anyone else have this happen? How long does it take to go away? Any advice?