Hi, According to the information provided, your BMI( Body mass index) is 16.26 kg/m2. Normal BMI is 18-24.9. You are underweight. But you can gain weight easily by improving your intake naturally (without any powder) unless there are no other concerns. Since I do not have the exact amount of calories or type of food you consume, I can give you general recommendations only. Overall increase in the total calorie consumption by 500kcals per day can increase your body weight by a pound in a week. Include natural proteins and fats in your diet like 2% milk and milk products, nuts( a handful everyday), an egg, legumes and lean meat, fish (if you consume meat). Consume fresh vegetables and fruits to get required amount of vitamins and minerals. Distribute your consumption throughout the day with 3 meals and 2 snacks. Protein powders are not recommended for weight gain. They can not only add excess calories but also damage your kidneys due to overload. For a healthy weight gain you need all the essential nutrients like carbohydrates, proteins, fat, vitamins and minerals. Physical activity can help build muscles which in turn increase your weight in a heathy way. Thanks