Tip 9. Consider A Mass Gainer
I know I bashed the supplement industry, but the truth is, if you really cannot eat any more whole foods (which is the better option) you could consider a mass gainer. A mass gainer is basically calories in the form of a shake. So instead of having rice, veggies and chicken, you could replace with a shake.
These are another option for between meals. But make sure you have three meals of real food and no more than three of these gainer shakes. Better yet, make your own shakes with fruits and protein powder. Much better option. OK, so start putting these tips into action and you should be sure to start go gain weight in no time at all.