Hi, thin shoulders usually happen due to low protein intake, lack of strength training, poor calorie intake, or difficulty in muscle building. To increase muscle around the shoulders, focus on a high protein balanced diet along with proper shoulder and upper body workouts.
Include foods like eggs, chicken, fish, paneer, tofu, curd, milk, sprouts, dal, nuts, seeds, peanut butter, oats, banana, and dry fruits in your daily diet. Also make sure you are eating enough calories and staying hydrated.
Next Steps
For better and faster results, a personalized muscle gain diet plan according to your body type and routine would help a lot.