If their status is "full" I wouldn't worry, but if they get injured or weaken for some reason, here are some suggestions (I'm still fairly new at this game so I don't know how effective they are.)
1) Bring your weakened villagers to the food bin and keep them there through several "meals". The status bar may increase a little with 4-5 meals.
2) Check the "desired" job to be Farming for a while (and train your farmers to be scienctists.) Foraging, Harvesting, Fishing (and probably even Watering) is less stressful than Research and they will start to recover.
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Isola is a magic island! All sorts of strange things can happen, and often do happen. -- arnie