deficient(lacking something essential) adjective [UK: dɪ.ˈfɪʃnt] [US: də.ˈfɪ.ʃənt]John's diet is deficient in protein. = La dieta de John es deficiente en proteínas.
feeble [feebler, feeblest](wanting force, vigor or efficiency in action or expression) adjective [UK: ˈfiːb.l̩] [US: ˈfiːb.l̩]
meager(poor, deficient or inferior) adjective [UK: ˈmiː.ɡə(r)] [US: ˈmiː.ɡər]