Expedient in this excerpt means for something to be appropriate to a purpose.
The fast food are affordable as it is cheap.It also convenient because it will take only a few minutes to prepare it.However,fast food bring negative impact to our body.It is because the fast food mix with chemical substances that are not good for our body.As the conclusion,we can eat fast food but we cannot make it as our daily food
Fast food restaurants would profit from offering vegan meals