I am 23, I daily walk around 3 to 4 kilometers. My weight is around 55 kg, and height is 5ft 8 inch. Is it a healthy weight, I want to gain a bit weight in a healthy way. I don't have much fat on my body which is a good thing I guess, but my face is not full, means it looks weak, so I guess I need some fat or mass on my face without being a fatty person. What should I so, what diet should I follow? Any advice? I would be obliged to you. than in advance!