fueling before a workout

I really need to fuel myself before or at the gym. I have been an on/off avid gym enthusiast, but my nutrition is really poor. As in, just not eating at all. I have tried many different protein or meal replacement shakes, but they all cause bloating, yuk! I don't make whipping up a quick meal, but it has to be quick as I have very little time before getting out the door. thanks for your help. Debra