Usn diet fuel rtds ready to drink is part of the usn weight loss range this 330ml ready mixed protein shake offers some great health benefits its high in protein fat free and is a quick easy and convenient supplement to drink any time of the day perfect for replacing meals or as a snack in between healthy meals usn diet fuel rtds ready to drink is part of the usn weight loss range this 330ml ready mixed protein shake offers some great health benefits its high in protein fat free