Your body weight should match your height. Calculate your body mass index (BMI). BMI is calculated by formula BMI = Weight in Kilograms / (height in meters x height in meters).BMI below 18.5 is underweight. Conversely, more than 25 is considered overweight and over 30 is considered obese. If you want to gain weight then gradual weight gain advisable. Maintain a BMI between 19 and 25. If it is in normal range then there is no need to gain weight. If you are underweight then natural process of weight is advisable. There are various causes of underweight like inadequate food intake, prolonged meal time gaps, and increased physical activity weight increasing food intake. Other reasons are mostly medical conditions like TB, cancer, malabsorption, hyperthyroidism, and anorexia nervosa etc. supplements are available for weight gain but such supplements contain very high amount of protein which can cause damage to your kidney causing loss of precious protein from body (proteinuria). You have not written your age. Breast size is totally genetic and it varies from woman to woman. There is no medicine or diet available for selectively increase the size of breast and buttocks. But cosmetic surgery is available. You can get a very good figure only by workout in gym. Advice 1. Adopt natural ways of gaining weight 2. Exercise – start workout in gym at least for half an hour for 4 – 5 days in a week regularly. start with a balanced mix of cardio, weight training and flexibility exercises 3. Take natural high protein like egg, soya bean, pulses, meat, and milk. Choose food with nutritional calories like potato, banana and dry fruits 4. Drink 3 – 4 liters of water daily 5. Chew the food properly to make it easily digestible 6. Avoid excess intake tea and coffee after meal as they contain tannin which hinders absorption of minerals like iron Thanks