Diet refers to the food and drink a person regularly consumes. Your diet is simply what you eat: if you eat lots of vegetables, fruits, and whole grains, that's your diet. If someone lives mostly on pizza and candy, that's their diet too.

People sometimes use the word to mean a special eating plan, usually to lose weight or improve health. Someone might say “I'm going on a diet” when they plan to eat smaller portions or cut out certain foods. But nutritionists remind us that everyone has a diet, whether they're trying to change it or not.

The word also describes what animals eat naturally. Lions have a carnivorous diet (they eat meat), while rabbits have an herbivorous diet (they eat plants). Humans are omnivores, meaning our diet can include both plants and animals.

You might also encounter diet as an adjective meaning low-calorie or sugar-free, like diet soda. Historically, a diet was also a formal assembly or parliament in some European countries, though this meaning is rare today.

What you choose to eat matters because food provides the energy and nutrients your body needs to grow, think, play, and stay healthy. A balanced diet includes variety: proteins, carbohydrates, fats, vitamins, and minerals working together to fuel everything you do.