Kenna Frankenfeld is a believer.
After losing 116 pounds while on the Atkins diet, the Lawrence teacher pitches the low-carbohydrate regimen to anyone considering a weight-loss plan. So Frankenfeld wasn't about to be swayed Monday after learning of new evidence that one of the Atkins diet's cornerstones may be scientifically inaccurate.
"I'd like to know why it works out of curiosity," she said. "But bottom line is it doesn't really matter. It works for me."
The preliminary research, conducted at Kansas University, disputes the claim that Atkins dieters burn energy at a faster rate than other people because they eat a high proportion of protein. Atkins backers commonly refer to the claimed phenomenon as "metabolic advantage."
The project, conducted by Joseph Donnelly, director of KU's Center for Physical Activity and Weight Management, came at the request of the British Broadcasting Corp. The BBC program "Horizon" paid $10,000 for a model demonstration to test the energy-burning theory as part of a special on the Atkins diet.
"The real thing they were after was, is there any reason to believe there's something unique and advantageous about the diet?" Donnelly said. "You sort of get into the realm that something mystical is happening there."
Put to the test
Donnelly selected two test subjects -- twin men -- and determined how many calories they need to fulfill their energy requirements. One then ate that number of calories on an Atkins menu for two weeks, while the other ate foods that would be found on traditional low-fat diet menus.
He then used a calorimeter -- a small room that measures oxygen and carbon dioxide balance to determine energy expenditure -- to determine how many calories were burned by each man.
"We found no difference whatsoever," Donnelly said.
Filming for the BBC special occurred in October. The special aired last week and included other examples of research showing that even the late Dr. Robert Atkins, who developed the diet, didn't fully understand how it worked.
Donnelly is quick to note, though, that his test involving two men didn't comprise a scientific sampling.
"We don't claim this is an experiment," he said. "This is a mock-up demonstration. We showed, at very least, this is how we would do it."
Donnelly said his lab was applying for National Institutes of Health funding to conduct a complete trial.
Defending the diet
Even diet supporters agree it's possible that Donnelly's research could be correct and that Atkins' claims are unsubstantiated.
Mary Vernon, a Lawrence physician who is a top consultant for New York-based Atkins Nutritionals, said Donnelly's research wasn't conclusive because it involved such a small sample and short time period. The twins' metabolism would have been different over time because it takes days to burn off stored sugars, a step toward reaching the full Atkins effect, she said.
But she conceded that no study existed to conclusively back the metabolic advantage claim. Most Atkins research, she said, has focused on the diet's results.
"The science is pretty clear -- yes, it works," she said. "Why? Well, we haven't even started that. This little foray is the first into why it might work."
But she defended Atkins' decision to present the metabolic advantage theory.
"If he had waited for people to be willing to test his experience (as a physician), then millions of people would still be suffering," Vernon said. "He did whatever he had to do to get the message out."
Vernon said she welcomed the idea of federal funding to prove or disprove Atkins diet theories.
"That would be great. Let's go for it," she said. "Let's do the real science."
For Alice Lieberman, the scientific details of Atkins aren't important.
The Lawrence resident said she had found Atkins more effective than the other diets she's tried. She has lost 14 pounds, and kept them off, in the past year on the low-carb diet.
"I like to say I've lost 10,000 pounds over the years, five pounds at a time, back and forth," she said. "The mechanism of Atkins eludes me, but all I know is it works."