I just coached my best friend through this same situation. I have three children; ages 9, almost 4, and 22 months. I breast fed two of them, bottle fed one. Someone already mentioned that this makes a difference: it does. My bottle fed boy had no trouble sleeping through the night by the time he started polishing off an 8 oz bottle at bedtime (around 20 weeks old ). He woke occasionally, but it was never hunger.
The other two, breast fed, well...they were both tough to get to sleep through the night. And by "through the night" i mean a solid 6 hours. I don't know why, but breast babies just love to eat (ok, maybe I do know why (-; )...
If you are concerned that your baby might be hungry- stuff her to the gills before bed. So, say she goes down around 7:30 and you go to bed at 9; feed her at 9. She'll be sleepy, but do your best to get at least a few minutes in without fully rousing her. Change the diap if you can get away with it (my boys were easily roused so I only made this mistake once). This way, you know she has had enough to eat (logically). If she's waking up at 3 or 4 am, she might be hungry, or, an early riser. My second baby got up at 4 with the birds. He'd have his "breakfast" and then sleep till 9. This only lasted a few weeks till he just hung out in his crib without needing to eat. More proof that they won't starve to death over night.
But, if your baby is waking between 11 and 3 am, let her cry for 10 min. It's agonizing (and for us , this meant risking waking the other child(ren)) but listen carefully: is the intensity increasing? Or are there moments of quiet (they stop crying I think to listen " is mommy coming??") If she seems to be petering out, go a little longer and see if she settles. Sometimes they'll cry off and on for an hour, but as long as it's not desperate, all out wailing, let her be. If she's ramping it up, have daddy go in and try to comfort her. Nothing extreme. Just a pat, quick hug...
If the hug/pat "daddy treatment " doesn't help, try a diaper change. In the crib. In the dark (if daddy can manage). Then repeat the hug/pat procedure. Make sure she's not too hit it cold. Walk away and let her cry again.
If she settles , awesome. If not, now you can try a quick feeding. If it lasts for less than 5 minutes, baby wasn't hungry. She MIGHT have been thirsty. Try a humidifier if you're in a very warm climate (and she might be sweating) or if it's cold and dry.
FYI- i did all of this stuff and still was woken every three hours by my "Besty best pesty pest". I thought my youngest would NEVER sleep through the night, until one night I desperately put him down in my room in a pile of laundry ( whilst i arranged myself for a feeding) and he passed out instantly. Apparently, my scent was enough. I scooped him up, dirty t shirt and all, deposited him very unceremoniously in his crib and he slept like -well, like a baby! - for 5 more hours. Try sleeping with your baby's clean sheets for a couple nights before you put them in the crib and see if she sleeps better when her crib smells just like mommy. This was kryptonite for my youngest.
Once you get her to quit waking up in the wee hours, adjust the last night feeding to as late as you can stand it at first, then gradually move it closer to the baby's bedtime. This sometimes means she'll wake up earlier. My breast fed kids never went more than 7 hours. I adjusted that window to suit my needs. I wanted to sleep in so I let baby stay up later. You do what suits you.
My friend just did this with her first baby (always toughest with the first!) and despite her disbelief, and her husband's insistence that the boy was hungry, her baby only cried for ten minutes the first night and then settled on his own, and cried once more two days later for 5 minutes, and now sleeps 8 hours! She has to wake him now because she can't stand the morning engorgement! And he's certainly not losing weight, so, this proves it had nothing to do with a NEED to eat at night.
So, should you let your baby cry it out? I think so. It's really really awful to listen to, but, in the long run, it's worth it to FINALLY get a good nights rest. An added benefit is that they often sleep better during the day because they know how to drift in and out of sleep on their own. Someone here mentioned ~45 min of crying...nerves of steel! I've had nights where it lasted a half hour (when my baby was a little older and I KNEW he wasn't hungry-just a pest) and he survived, as did the baby who cried for close to an hour ( persistent little fella!)
Btw : if you think it's hard now - try to imagine getting a two year old to break a bad habit. Not gonna happen. Do it now ! 7 mo olds are MUCH easier to train!
I hope this helps.