Virtual Box to Live USB (Kali Linux)

Hey, guys! Hope you are staying out of trouble.

What I want to know is; is it possible to transfer a virtual box machine(which is Kali Linux 2.0 here) to work in live usb mode?

I have been using kali on virtual box(host: windows 7) since the beginning, but I've always had problems of memory, speed, storage with it. So, I want to use it in live usb mode so that it can take in use all my computer's RAM along with other advantages it offers.

So, would I have to start with a whole new machine in usb mode? or is there a way with which I can transfer my current Virtual Box machine to work as live usb?

Please answer quickly.

Thank You.