If you undereat before the hike, you might run out of energy halfway up the trail.

He undereats because he worries about gaining weight.

After the long hike, Maria remained an undereater, nibbling at her dinner and leaving most of it untouched.

The nutritionist held a support group for undereaters struggling to regain a healthy relationship with food.

He's undereating because he's anxious before the presentation.

Many of the desserts remained undereaten after the party, so we packed them up for donation.