Eat your veggies? Idk
I drank milk, protein shakes, and ate whatever food I could get my hands on ( except junk food) for the 2 months I went gym, went from 169.5cm to 172cm by the 3rd month. I was 17 at the time and now well over 18 so now I'm like 173cm-174cm. It might or might not work for you but you can always try....