That rather fat gnoll lady is one of the few gnolls who didn't want to join the massive army that was trampling the continent of Set'al. When her village's leader refused to join, Yenoghu sent a lone berzerker called Red Eye to kill every last one of them. She was the only one that survived, remaining hidden in a small tunnel under her tent. As soon as they'd moved on, she ran for the nearest town, still quite young, which took days on her short legs. When she got there, she collapsed in the streets, and although everyone saw that she was a gnoll, all of them saw her for what she was - a little girl in need. Someone took her in, fed her and clothed her, but the memories of her family being killed were too much, and whenever she thought about it, she started to eat. at first it was little stuff, maybe an extra helping of dinner, but it grew as she did, and when she was old enough to move on by herself, she found that she was spending entire payments from her job on food.

This is her now - about 34 years into her life, she practically lives inside of the Drooling Dragon restaurant. The owner knows her quite well, and as shy as she is, he still tries to find out what's wrong, going so far to make her comfortable as to even make her meals free.
She definitely appreciates his company, especially with the stress of those memories combining with the jeers on the street about her weight.