Final answer:
The three keywords to a healthful diet are balance, variety, and moderation.
Step-by-step explanation:
The three keywords to a healthful diet are balance, variety, and moderation. A healthful diet should not only include a variety of foods from all food groups, but it should also be balanced in terms of consuming appropriate amounts of all nutrients. Moderation refers to not eating too much or too little, and it is essential to maintain a healthy diet.