You must have sweated off hundreds of calories during that Spin class, so it’s totally okay to indulge in a bowl of ice cream when you get home—right? Not so fast. Research shows that people tend to reward themselves with rich foods and large portions after exercising, and that they often eat back all of (if not more than) the calories they just burned. There’s nothing wrong with small snack or a filling dinner after exercising, says Emily Brown, RD, a wellness dietitian at the Mayo Clinic in Rochester, Minn. and former professional runner. But before you dig in, you have to understand your body’s true nutrition needs so you don’t end up gaining weight despite all your hard work. Read on for the smartest ways to refuel—and silence that rumbling belly.