I get this question a lot. It only comes down to a few things but first and foremost you need to have discipline to accomplish this. This is a very hard thing to do but if you are strict with your diet and training methods it won't be as difficult.
In regards to your diet you need to be cutting back on your carbs and increasing your protein intake. So meats, chicken, eggs etc. You should also be adding a protein shake in between meals as well. trying to eat 1 gram of protein per pound of body weight everyday. Now, for the carb portion, you need to cut back not cut out. Carbs give you energy for the workouts you perform. If you cut back on them the body will begin to burn fat and not just the carbs if you lift properly.
Your workouts need to have high intensity. If they don't, you will not be burning fat. You need to be doing a lot of sets with a lot of reps. About 10-15. And taking less rest in between sets. Instead of 1 minute take 30 seconds. This will help you burn more calories and ultimately burn more fat while increasing muscle. I really hope this article can help you guys because this is a very common question and not an easy goal to achieve.