She whispered to me that she was hungry.

Literal

She [topic-は] me [to-に], stomach [subject-が] is-empty [quotative-と] whispered.

お腹がすいている is the standard way to say 'I'm hungry' in Japanese — literally 'the stomach is empty,' with the body part as the subject of the predicate. English uses an adjective ('hungry'); Japanese narrates the bodily condition. The verb ささやく ('whisper') is more vivid than the bland 言う and conveys the intimacy or secrecy of the moment — perhaps the speaker didn't want others at the table to hear. The ~ている here marks a continuing state rather than an ongoing action.