She is underweight according to her height. She should be around 47-50 kg depending upon her physical activity level. Tyr to add nutritious meals in her daily routine. For weight gain, don't rely only on chappati or curry that you normally make. Try to consume a good portion of every food group each day. Most importantly, fix the timings of her meals. Scheduling her routine will help a great deal. Add seasonal fruits in every meal. Add raw vegetables more in her diet as they are more nutritious than cooked ones. Eating a large portion size won't help her, its the nutrients that are important. Consult a Dietican for a detailed diet plan for her.
She is underweight plus she is in her growing age... add healthy nutrient dense food to her diet.feed her 4 big meals and 2 snacks..add litght activity to her life like walk or running...see her sleeping timings.Add vegetables,fruits,milk.butter,protein shake,dark chocolate,desi ghee(portion control)banana date shake,nuts,tuna,eggs,cheese to her diet. Dont go for junk or abnormal ways yo gain weight.YOu can Consult me for a proper diet plan @ email@example.com
By the time a woman is 20 years of age, they are done growing. She should be seen by her GP and have her blood work done to make sure there is no underlying medical issue causing her to be under weight. If all is normal, then her dietary habits need to be analyzed. Add high density nutritious foods such as nuts and dried fruit to her diet to help increase calorie consumption. Make sure she is spending 30-40 minutes in the morning sun each day, and that she is walking 20-40 minutes each day.