A Dietitian for Weight Gain is a healthcare professional who specializes in creating personalized nutrition plans to help individuals gain weight in a healthy and sustainable way. They focus on increasing calorie and nutrient intake through balanced meal plans that include high-quality proteins, healthy fats, and complex carbohydrates. These dietitians work with clients to address underlying causes of underweight, such as fast metabolism, medical conditions, or poor appetite, and provide strategies to build muscle mass and improve overall health.