French

a group of soldiers or workers can only fight or function effectively if they have been well fed

給養(yǎng)充足的士兵（或工人）才能很好地戰(zhàn)斗（或工作）

on a full (或 an empty) stomach

after having eaten (or having not eaten)

飽（或空）著肚子

I think better on a full stomach.

我吃飽了才能更好地思考。

a strong stomach

an ability to see or do unpleasant things without feeling sick or squeamish

（看或做討厭的事時）堅強(qiáng)的性格