Can You Lean Out Through Diet?

In the past year, i've gained about 30 pounds, with half of that muscle. Is there a way to shrink but to keep the gains? Ih, i feel real strong. And like the bigger arms back and hamd strings i gained. I figure i can lean through diet. Well, well, ya. Diet's the key a. But it has to be a diet. It has to be nutritiona intervention that you can do. After every work out, you need to go for at least a walk. If you're looking to meet people, walk around pink dumbbells. They ask me questions about it.