Language changes over time, and "diet" is very commonly used as shorthand for "restrictive food intake" or "caloric restriction." But a reminder that "diet" is

Language changes over time, and "diet" is very commonly used as shorthand for "restrictive food intake" or "caloric restriction." But a reminder that "diet" is short for "dietary intake", and is not prescriptive. "A healthy diet" is a common phrase for "permanently good eating habits." The parent used context in an appropriate way that it's safer to assume they meant "dietary intake" than "restrictive food intake."