Focus on overall weight gain if you are underweight, since breast tissue can increase with healthy body fat gain
Eat enough calories to support gradual, healthy weight gain
Include protein, healthy fats, and complex carbohydrates in your meals
Do chest exercises such as push-ups, chest presses, and dumbbell flys to improve upper-body shape and lift
Maintain good posture to make the bust appear more prominent
Wear properly fitted bras for better support and appearance
Use padded or push-up bras for an immediate visual increase in cup size
Avoid extreme dieting, since fat loss can reduce breast size
Stay hydrated and get adequate sleep to support overall body health
Consider consulting a licensed medical professional about safe options if you want a significant change