This isn't all bad at times, but it might communicate to some in your group that you don't value the lesson portion of the your group meeting very much. Maybe they'll think it isn't worth the time to come. You're better off guiding the discussion and planning ahead so you can control the length of the icebreaker. Never underestimate the importance of creating an atmosphere where people feel at home. Icebreakers or other relational interaction are great for this, and you'll find that food always helps.
Food is power, they say.
It communicates to your group that you went out of your way for them. It also makes people feel more comfortable. Jesus taught 90 percent of the time in the context of a meal. I wasn't a Christian when I was invited to my first Bible study. My leader brought cookies to that first group.