。
She advised him not to overeat.
Literal
She [topic-は] him [to-に] eat-too-much [not-to-ないように] advised.
The ~ように + reporting verb pattern, here with 忠告する ('advise, warn'). The negative 食べ過ぎないように ('so as not to overeat') frames the advised behavior — ように attaches the desired outcome of the advice. 食べ過ぎる stacks 食べる ('eat') + ~過ぎる ('do excessively') — a productive compound pattern for 'do too much.'