Peanut butter-- either in a sandwich (delish with nutella!) Or just take a big spoonful as you are passing by. And not too high in sugar, depending on brand.
Or if you just want the most convenient calories possible for snacking, pop tarts are 200 calories per tart--1600 per box of 8-- cheap, and you can eat them almost anywhere, anytime. But they are kind of a blend of refined sugar and trans fats, so consume at your own risk.
Grapes. Wash up a big bag of them, then they are really easy to keep snacking on, and make a break from some of the heavier stuff.
If you can stand it and afford it, half-n-half instead of regular milk. A lot more fat and calories.
Fruit juice can be an easy way to drink calories, but again all sugar, so if you don't want too much sugar I'd lean more on the milk/cream.
Personally I find that less than an hour after eating oatmeal for breakfast I'm ravenous, so could start your day with a big bowl of that, then have second breakfast a bit later.
I hope that was some help :-)
9 years