Like Doug said below, it would depend on the type of loan you are doing and what the updates are. If you just want to update the kitchen, bathrooms, ect..., then you could do any loan as long as the house passes the inspection. If the updates are just to make the house more modern, then you can do it yourself as long as you get the proper permits.
The only reason, it would affect a loan would be if the updates were needed to bring the house up to code.
I hope this helps and let me know if you have any more questions,