The truth is that you can build upper body strength and muscle using only your body weight. Marco is right! You can at least invest in a pull-up bar.
You can try this workout:
- Plyo Push-ups
- Chin-ups
- enter link description hereChair DipsChair Dips
- Plank Pelvis Crunch
- Side Plank Pelvis Crunch
Try to perform 3 sets of 12-15 reps (work your way up) 3 days per week with one day of rest in between for 3-4 weeks. After that, you have to follow the progressive overload principle to continue to build strength and muscle.
You must also eat clean and eat more healthy calories:
Sweet potatoes, egg whites, chicken breast, grilled fish, peanut butter, avocados as they are loaded with good carbs and proteins.
You can change to these exercises once you can perform more than 15 reps easily to continue to follow the progressive overload principle:
Gator plyo push-ups, pull-ups, decline plyo push-ups, etc.
Good luck!