The Bracketing Method
The Bracketing Method involves cycling your carbohydrate intake over the course of the week based on the type of training you're doing.
Let's say you train with weights three days a week. On non weight-training days, you consume a basic "fat-burning" diet (see How To Burn Fat Without Losing Muscle for step-by-step advice on how to set this up).
On the days you train with weights, follow the same diet but bracket your workout with extra carbohydrate and protein, following the guidelines for pre-, intra- and post-workout nutrition described in A Simple But Powerful Way To Trigger Faster Muscle Growth. What this means is that your calorie intake is increased on weight-training days.
One variation on this method, which is particularly useful for anyone wanting to drop those last few pounds of "stubborn" fat, is to maintain calorie intake at the same level and simply alter the percentage of calories coming from carbohydrate and fat. Protein intake is kept the same.