In this statement, it may be helpful to state that "it" refers to what Jesus had said. Alternate translation: "He must have said that because we have no bread" (See: [[rc://en/ta/man/translate/figs-explicit]])
The word "no" is an exaggeration. The disciples did have one loaf of bread ([Mark 8:14](./14.md)), but that was not much different from having no bread at all. Alternate translation: "very little bread" (See: [[rc://en/ta/man/translate/figs-hyperbole]])