The first thing you need to consider when working out is what matters most? Is it how much muscle mass you have or how many calories you burn? If you want to lose fat, then focus on losing weight. However, if you're going to build muscle, then focus on building muscle. It would help if you kept in mind that you cannot gain strength while losing fat. So, if you want to lose fat and build muscle simultaneously, you'll need to do both using a barbell.