Can you correct the mistakes?

perhaps:

Nowadays, it's easier for young people to buy fast food because of the many fast food restaurants/joints around. However, the negative side is that fast food causes health and weight issues to those who frequently consume this kind of food.

There is still some "flow" issues with this, but I hope it helps.

Can you correct the mistakes?

It is easier for young people to buy fast food due to the facility nowadays,which simultaneously brings health and obesity issues to those who frequently buy this kind of food.