Now Fatburger has unleashed the "Skinny Burger," where the bun is the burger. No, really. Fatburger has taken its 1/3-pound patty and sliced it in half, then put cheese, pickles, onions and condiments in between.

Then came the KFC Double Down, a caloric Armageddon where the bun was replaced by two breaded, fried chicken fillets and stuffed with beef, bacon, and who knows what else.

First there were bun-free, no-carb burgers, pioneered by chains like Carl's Jr. and Hardee's. The patty and all the fixings were sheathed in lettuce leaves.

It's a lot of meat, but apparently not a lot of calories. "This is a 320-calorie burger," said CEO Andrew Wiederhorn, as he displayed the medium-sized version of the meal, which has cheese but no mayo. That's about 250 calories less than a regular Fatburger. "You get to have a milkshake once in a while," Wiederhorn said.



Yours truly tried one, as the video shows here. Perhaps most surprising about all this is that the all-meat bun isn't nearly as messy as you might expect.

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Fatburger's CEO said the Skinny Burgers are accounting for 10 percent of company sales, but they're being rolled out as beef prices hit record highs. The government reports that ground beef is now selling on average for a staggering $4.10 a pound. Wiederhorn said his franchisees are trying to manage those costs and still maintain margins of between five and 15 percent.

"We've seen a 25 percent increase in beef prices," he said. "It now costs 25 to 50 cents more to have a hamburger than it used to." He said that cost is being passed through to consumers, "No different than if it's the Affordable Care Act or minimum wage increase."

Wiederhorn said despite the price hikes, sales are up, as customers appear willing to pay more for what they consider a quality hamburger. The company has 200 stores in 32 countries, with another 350 in development.

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"Our biggest growth in 2014 has been in Asia—Philippines, Singapore, Malaysia," he said. Not every country will allow Fatburger to use U.S. beef, however.

"In some markets like Indonesia, we have to use French meat," he said, which is more expensive. Also, while U.S. beef is allowed in Macau and Hong Kong, "in mainland China, it's prohibited, and we use Australian beef."

As for whether the burger sector is getting a little crowded, Wiederhorn believes Fatburger will succeed by sticking with a burger recipe that's worked in the past.

"We're going after that customer at McDonald's or Burger King, and dragging them up to our space. We're going after the casual dining customer at a Red Robin, and dragging them down to our space, because of the price point."

A price harder to maintain as demand for beef continues to outstrip supply, keeping the Skinny Burger's margins skinny as well.