The experiment, funded by the Robert C. Atkins Foundation and initiated by Penelope J. Greene, a visiting scholar in the Department of Nutrition at HSPH, attempted to determine whether the effectiveness of so-called low carb diets is a thing of myth or reality.
Greene said she started planning the study in 1999, and was initially surprised when the Foundation did not have any data on the subject matter. She said she took the initiative to design the project and train those involved.
The experiment’s low carb diet, however, was not the same as the Atkins diet, since the test meals consisted of only poultry and fish in order to keep the protein sources standard.
The study attempted to determine the different outcomes of people consuming the same amount of calories but varying amounts of fat and carbohydrates.
Test groups included those on a low-fat diet, as recommended by the American Heart Association, those on an ultra-low carb diet, and others on an ultra-low carbohydrate diet with 300 more calories allowed per day.
Using male and female subjects 50-years old and older from the “baby boomers generation,” Greene said she and her colleagues attempted to test those at high risk of diabetes and cardiovascular problems.
Greene said the majority of participants were highly concerned about their health and consulted their families and physicians routinely during the experiment.
“Most of them were overweight and over scared,” she said.
The food given to the test subjects was freshly prepared under a special recipe developed by Greene at Marino’s, an Italian restaurant in North Cambridge.
According to Greene, the experiment tested claims—similar to those of the Atkins diet—that if one eliminates most carbohydrates in one’s diet, the body resorts to using fat stores as a source of fuel. These fat stores are burned through lipolysis, a process which converts the body’s stored fat into energy.
The results of the experiment, which seemingly affirm these assertions, were “surprising,” Greene said, in that those test subjects under the ultra–low carbohydrate diet exhibited a significantly greater weight loss than other participants.
“The experiment certainly provides evidence [that a low carb diet is effective],” she said.
Greene claimed that the no one has ever done this kind of experiment before on an outpatient basis, which she said was made possible by “really, really good” food which kept participants from snacking outside their prescribed diet.
Many critics said that the results of the experiment violate the laws of thermodynamics, since the test subjects in certain groups lost more weight than their caloric intake. The experiment’s results also challenge classical nutrition theory, which mandates that the intake of calories should equal the amount of calories expended.
“The results were different than expected from the Classical Nutrition theory, however, I don’t believe it violates the laws of thermodynamics, rather there is more than one way for calories to leave the body,” said Greene, counting excretion and perspiration as ways calories are used.
“We don’t necessarily understand the mechanisms by which calories are used,” she added.