Hi, I am a 14 year old girl 5'1'' how much should I weigh? Right now I weigh 78.4 pounds is that healthy? Can you also tell me how to gain weight?

Thin side. Your current height is at the 20th percentile for your age. At your current weight, your BMI (or weight for height) is 14.8 or underweight. Your ideal weight would be 95# (20th percentile for your age). To gain more weight, concentrate on eating healthy foods, just a little more of them. You can also try protein bars. .