Underfeed (verb)

1. To give less food than is required or needed.
2. To feed an animal or plants less than is needed for proper growth or health.

Origin:

Early 19th century: from under- + feed.

Examples:

1. The baby was underfed and not getting enough nutrition.
2. The plants were underfed and not growing well.
3. The animals were underfed and became weak and malnourished.
4. The workers were underfed and had to supplement their diet with their own food.
5. The fish in the tank were underfed and not growing at the expected rate.