Key principles of a balanced diet include consuming a variety of food groups, incorporating adequate macronutrients like carbohydrates, proteins, and fats, and focusing on whole, unprocessed foods. It's essential to maintain appropriate portion sizes and limit added sugars, sodium, and unhealthy fats. Including a wide range of fruits, vegetables, whole grains, lean proteins, and healthy fats promotes nutritional diversity. Staying hydrated and adjusting dietary choices based on individual energy needs, activity level, and health conditions are also critical components of a balanced diet.