A bit shocked Bonney is Kuma's daughter. I thought their relationship would be that Kuma was her savior and she felt indebted to him. This is because of Kuma's resemblance to Ninomiya Sontoku.
He helped prevent famine in the past, and I figured Kuma, as a Revolutionary, helped save a country from starvation, that being Bonney's hometown, as she's depicted poor as a child and surrounded by food she likely never experienced until now.
Either way, I imagine Kuma still helped her from getting hungry as a child and to never take it for granted. That'd be a pretty powerful way to explain her voracious appetite.