Meaning: He consumed the first meal of the day with great joy.
Choice of Words: "Ate" means to consume food. "Breakfast" is the first meal of the day, usually eaten in the morning. "With gusto" means that he ate with great enjoyment and enthusiasm.
Alternative Expressions
He devoured his breakfast with relish.
Meaning: This means that he ate his breakfast very quickly and enjoyed it very much.
Choice of Words: The word devoured means to eat something quickly and eagerly. The word relish means to enjoy something greatly. So, when you devour your breakfast with relish, you are eating it quickly and enjoying it very much.
He inhaled his breakfast with gusto.
Meaning: This means that he ate his breakfast very quickly and enjoyed it very much.
Choice of Words: The word inhaled means to breathe in quickly and deeply. When you inhale your breakfast, you are eating it very quickly. The word gusto means enthusiasm or enjoyment. So, when you inhale your breakfast with gusto, you are eating it very quickly and enjoying it very much.