I have posted a link to this article before, but it speaks to your question. At least one study found that eating in the morning on an empty stomach prevented weight gain. How applicable the study is to folks who are dieting is questionable. www.thatsfit.com/2011/02/21/when-is-the-be
I generally try to workout in the morning to get it out of the way and rarely eat anything beforehand. I successfully lost 30 pounds and have maintained that loss. That said, I think it may vary by individual. SOme people feel ill and just can't put as much energy into a workout without fueling up.