You can have your cake and keep your figure . . . if you exercise wisely. Dr. Konishi offers a diet and exercise energy equation (Energy In = Energy Out) designed to give bingers their time at the table without bulgy aftereffects. All you have to do is compensate for the calories with additional exercise as computed in his Exercise Equivalence Tables. Say you crave a jelly doughnut--226 calories. Before you eat it, you can walk for 44 minutes, swim for 27 minutes, or run for 12 minutes, and that expenditure of energy will cancel the added calories. It's an easy enough scheme to follow, it's introduced with some snap, and it begins with the assumption of basic good habits: a balanced diet and regular aerobic exercise. No padded promises then, but a new game plan for weight watchers to tackle.