If your goal is to lose fat and build or maintain muscle at the same time, you really need two things: 1. A workout regimen that includes strength training 2-3

If your goal is to lose fat and build or maintain muscle at the same time, you really need two things: 1. A workout regimen that includes strength training 2-3 times a week and ideally also some form of moderate aerobic exercise (lots of walking is fine). 2. A diet that is at or below your basal metabolic rate (if you're an adult male that usually means somewhere in the 2,000-2,500 calorie range) and is high in protein (for muscle growth/maintenance), medium in fat (for satiety and hormone production), and low in carbohydrates and alcohol (for limiting blood sugar spikes).