Some offices that have snacks around have packets of microwave oats. They're easy snacks and breakfasts, and you just need a bowl and some water, but they're a little boring. The fix is easy: Grab a banana. Bring one from home, or maybe there's one in that same pantry. Rather than cut the banana into slices to top your oatmeal, mash it in the bottom of the bowl and add the oats and water (or milk!) on top. Halfway through microwaving, stir everything together to make sure the banana and oats mix evenly. Not only will you end up with a tastier snack, the banana will add bulk that will keep your fuller so you can focus on getting stuff done and not on a rumbly stomach.
Even if your office doesn't have snacks at all, just throw a banana in your bag in the morning along with a packet of microwave oats. You could even bring a couple of bananas and a box of oat packets in at the start of the week. The riper the banana is, the better it will work.