You should eat 5-6 times a day. Between each wait for about 2hours.
For example mine plan of eating:
Breakfast:
oat flakes + milk + banana
At snack:
2 wholemeal rolls + chicken ham or chicken meal + some vegetable
Lunch:
chicken meal + rice or pasta + some vegetable
Snack:
2 eggs + wholemeal baguette
Snack:
pound cake + milk
Dinner:
Fish + potato + some vegetable
2nd dinner:
Some fruit (for example banana, apple) or legume (soya is the best)
Before sleep:
curd
I started at 54Kg with height 170cm (+/-). And for about 4 days of this plan I gain 2 good kg
. And now I am still at 56. Now looking forward to 60!
And do you do any sport? If yes, then thats may be the problem why you cant get kgs on...