User blog comment:Xilinoc/Ch. -547 - The State of Affairs op. 1 - "Expectations"/@comment-1351982-20130724152551/@comment-2211792-20130724174635

No, but your meal is broken down to its basic components. Some are absorbed into your body, the rest becomes poo. I think the same happends to souls consumed by Hollows, excluing the poo part: they are broken down to reishi. Remember, Hollow animals in Hueco Mundo can survive by getting reishi from air and sand.