You DO NOT need to lose fat to build muscle. Do not listen to this person…they have no idea…
Think of your body as a car. A big muscle 300lb guy is a "hummer" whatever he does he requires alot of food (gas for the hummer). He needs alot of it to keep that massive body going. The more muscle you have, the more fuel your going to need. Especially when your doing a hard workout, your muscles are burning at full force.
You CAN build muscle to burn fat. Although YOU DO need to watch what you eat, lean meats, good carbs, good fats…(fats and carbs wont make you fat, dont get sucked into that)
But as basic as it gets, if you want to lose fat, burn more calories than you take it…