Chipotle Mexican Grill (CMG -1.34%) is known for its natural ingredients, but did you know that it used to be owned by McDonald's (MCD 0.37%)? Learn more about that and other surprising facts below.

1. A Chipotle burrito contains more calories than a Big Mac.
A steak burrito with white rice, sour cream, cheese, and guacamole contains more than 1,000 calories and 1,590 milligrams of sodium. By comparison, a McDonald's Big Mac contains 550 calories and 970 milligrams of sodium.

But sodium and caloric content are the only two categories in which a Big Mac could conceivably be labeled healthier than a Chipotle burrito. The burrito contains twice as much protein and more vitamins and minerals than a Big Mac. However, just because it is natural does not mean it cannot make you fat.

2. Chipotle is more obsessive than Starbucks when it comes to customer experience.
Starbucks (SBUX 0.53%) is known for paying close attention to its in-store environment; the world's largest coffeehouse chain is known to many as their all-important "third place:" There is home, work, and Starbucks. The stores' inviting interiors and cozy environment are at least as responsible as the coffee for driving foot traffic.

Chipotle takes a similar attitude toward customer experience. It carefully compiles a new 500-song playlist to beam out to its locations each month to ensure that regular customers do not have to listen to the same songs over and over. The music is carefully crafted to match the stores' interiors, which typically include concrete floors and lots of windows.

In addition, the playlist is set up so that a faster song plays during the lunch rush hour and a slower song plays during the afternoon slowdown. Clearly, Chipotle is obsessed with its customers' experience.

3. McDonald's used to own a majority stake in Chipotle.
Other than serving high-calorie food quickly, there really aren't any similarities between McDonald's and Chipotle. Yet the world's second-largest fast-food chain (Subway is the largest) bought a controlling interest in Chipotle in 2001. Chipotle used the investment to rapidly expand its store base -- all of which are company-owned.

McDonald's divested its interest in late 2006, the same year that Chipotle had its initial public offering. Luckily, Chipotle maintained its independence during the entire ownership period and its unique style remains.

4. Investors like Chipotle much more this year than they did last year.
Most high-growth stocks trade at insane multiples, and Chipotle is no exception. The stock trades at 53 times trailing earnings, or $525 per share; at the end of 2012, it traded at 34 times trailing earnings, or $300 per share. The higher multiple on a higher trailing-earnings figure reflects renewed investor optimism about the company's prospects.

It could also be a reflection of the dearth of successful companies in the quick-service industry at the moment. Even McDonald's has encountered same-store-sales slowdowns due to low consumer spending in many parts of the world. In stark contrast, Chipotle's same-store sales rose 6.2% in the third quarter and the company raised its full-year guidance. 

Of course, it is extraordinarily difficult to handicap a high-growth company; at $300 per share, it was possible to make a compelling case that Chipotle was undervalued. At $525 per share, investors are paying full price (and maybe a little more) for whatever magic Chipotle can pull off in the coming years.