Look into the Keto diet. It is pretty intense but it works amazing for some people.
Basically, you set your body into a stage called ketosis. Basically it is starvation mode, without the starvation. To do it, you eat VERY few carbs, and lots of oils/fats. The point is, your body naturally gets its energy from glucose which is broken down from the carbs you inject. And while working out on this diet is fine, it is hard to lose fat, while building muscle. With keto, your body switches over to use your fat reserves/intake as an energy source. When this happens, your muscles still grow but your body fat decreases, very efficiently. To really look into it, search for the diet on the forum you are reading now. It is not a long term diet, as it is bad for your liver in long term settings but for short term it does a great job.
Edit:
Be ready to eat a TON of food on this diet. 7 square meals is just a start…