Why not try a  nutritious shake which will give you the necessary nutrients without causing your blood sugar to go high . These shakes are low glycemic which means they will turn to sugar slowly after consuming. Since you wish also to put on some weight these may be the right kind of drinks you need when you take it into between your meals.

They come in 3 flavors - chocolate, strawberry and vanilla. They are packed in convenient sachets which you you can reseal easily- convenient to keep in the office.