Losing weight without losing your chest

In the past 6 months I've gained about 10lbs. Before I begin my rigorous excerises to lose that weight I wanted to ask this: what excerises can I do to ensure I do not lose too much of my chest as well? I am a double D size and always have been. And I understand that no matter what, I will lose some of my chest. I just want to keep as much as I can. Thoughts?