I follow Lean Startup and similar concepts in my own ventures.
That said, investors are interested in making sure they get their money back several fold. At best, they will want to know how Lean Startup will accomplish that, but I'd do you a disservice if I did not warn you that some people, especially money people, look at the lack of a 5 year plan as a lack of foresight and business understanding, as incorrect as that may be.
So, challenge yourself with this exercise: paint the investor a picture of a few ways where you could make money and make sure they are well researched and cannot be shot down. Then, continue this thought exercise and account for costs and cash flow. The point is to show that you know how to run a business, not just how to build a product. Show the investors the level of detail that gives them that warm fuzzy feeling that their money has a good chance of getting paid back many-fold in a matter of years.
Investors may be current or prior entrepreneurs or executives and some might have good or bad experiences with Lean Startup as they implemented it. Best to be prepared to talk in the language investors speak.