How to gain weight?

Step 1 Once you reach target, add 250 calories a day to your existing daily calorie intake. This means if you’ve been having 1,250 calories each day, you should now have 1,500 calories a day. Step 2 After a week, weigh yourself on your usual scales. You’ll probably have lost a little more weight. If so, add another 250 calories to last week’s daily allowance. So, if you were having 1,500 calories a day, now have 1,750 calories daily. Step 3 After a week, weigh yourself again. If you’ve lost more weight, add an extra 250 calories to your daily intake, for example from 1,750 calories to 2,000 calories each day. Step 4 After a week, if your weight has stabilised that’s the amount of calories you need each day to keep your new slim shape. If you’ve gained a tiny amount, drop your daily calorie intake by 100 calories, for example, from 2,000 calories to 1,900 calories daily. After a week, weigh yourself again. If your weight has stayed the same, that’s the amount of calories you need each day for weight maintenance. If your weight has gone up or down, juggle your daily calorie intake by 50 calories a day until your weight eventually stabilises. Step 5 Weigh yourself once a week on your usual scales until you are confident that you’re maintaining your healthy weight.

I would say eat as many potatos as you can !!! Or you can use wait gainer shakes !!!