Bodybuilding for skinny girls with the goal of increasing muscle size and strength requires resistance training (with weights and body weight) and proper, high-calorie nutrition. Workouts should focus on multi-joint movements such as squats, deadlifts, chest presses, and pull-ups, and gradually increase their intensity. Adequate protein intake from food sources (such as meat, eggs, dairy) and healthy carbohydrates and fats are essential for energy and muscle growth. Also, excessive aerobic exercise should be avoided, as its calorie burning can interfere with the goal of gaining weight and building muscle.