Here are suggestions to fill in the blanks:

1. **important**
2. **eat**
3. **drink**
4. **problems**

So the completed text would read:

"Eating a balanced diet is (1) **important** for teenagers to stay healthy. This means (2) **eat** various foods, like fruits, vegetables, whole grains, and proteins. Teens should try not to (3) **drink** too many sugary drinks or eat too much fast food because these can cause weight gain and health (4) **problems**."