I'll be 37 in 2 months & I weigh 137lbs & 5ft 8 inches, oh plus I'm a male. But all of my life I've always been small. 95% of my family is on the light side, the heaviest of that number is maybe 185lbs. I use to try just bout everything to gain weight including protein shakes & lots of exercise during my late teens (USAF Basic Training), still didn't help. I just have a high metabolism so I don't even try any more. But hope u find something to help u gain the amount u want. Good luck.