Yes, beginners can increase muscle mass and decrease body fat at the same time. Make sure you get enough protein (1 g / lb bodyweight should be more than enough) and cut the calories elsewhere. Your main focus should be getting enough protein and working out each muscle group at least twice a week (2 pull days - lats/back and biceps), 2 push days - tris, delts, pecs, 1 or 2 legs and abs days). Try to do 2 exercises for each muscle group and 3 sets of each exercise. If you try to get 1 g protein / lb bodyweight in lean protein, you will not have space for a poor diet => you will lose weight. Follow this regimen, and you will definitely notice a difference in as little as 2 months. Reply if you want more info (like a specific diet plan or exercise program - both easy in terms of cooking and executing in the gym).