As we age,we need to eat less because our bodies need fewer calories to function properly.
问题描述：
As we age,we need to eat less because our bodies need fewer calories to function properly.
我想问的是to function properly是不定式吗?
答
need sb to do sth意思是“需要某人去做某事”,意思是需要更少的卡里路来维持、运转（身体）