Obesity center studies low-carb diets

The Center for Obesity Research recently led a thorough study of the effects of low-carb versus low-fat diets.

The Center for Obesity Research and Education at Temple recently led the longest study conducted in the United States on a low-carbohydrate diet, while comparing its long-term effectiveness with a low-fat diet.

The study randomly assigned the two diets to 307 adult participants, who each weighed more than 220 pounds. Half of the people were placed on a low-carbohydrate, Atkins-style diet and the other half was placed on a low-fat diet, which consisted of an intake of 1,200-1,800 daily calories with less than 30 percent from fat.

Dr. Gary Foster, director of CORE and lead investigator for the study, said one theory of the study expected low-carbohydrate diets to be easier to maintain for a short time period, but harder for people to stick with for the long-term.

“Tens of millions of people were buying the Atkins book, and there weren’t any control trials looking at its positive or negative effects,” Foster said.

In response, CORE collected and analyzed data of participants for two years within the Philadelphia area as well as from two other academic medical centers: Washington University in St. Louis and the University of Colorado in Denver.

Foster said his team of researchers wanted to create a comprehensive study that would give “the best case scenario” for each diet. The clinical trial systematically measured participants’ levels of cholesterol, blood pressure, bone mineral density and body-fat percentage.

Participants at each center consistently attended a behavioral support program throughout the study. The program sessions discussed goal-setting, self-monitoring and limiting triggers to overeating in the context of each dietary program.

The average age of participants in the program was about 45 years old, which is typical for weight loss trials, Foster said.

“I think college-aged students are underrepresented in studies like this often for scheduling reasons,” Foster added.

This raises the question as to whether current obesity studies include a fair representation of college students.

Contrary to the expectations of the research team, both groups lost virtually the same amount of weight during the study. After the first year, participants had an average weight loss of 11 percent and about 7 percent the next year.

“Both groups increased High Density Lipids, but the low-carb increased it significantly more,” Foster said. “Most studies have shown that in the short term low-carb diets produce greater weight loss and over about a year they tend to level out.”

Anything above a 5 percent change is considered a success in the field.

“People can lose weight with either diet, and people should probably be less concerned with which diet they follow and more concerned with using behavioral strategies to stick to the diet that they choose,” Foster said.

Funding for the study was provided by the National Institutes of Health. The study was published in the Aug. 3 issue of “Annals of Internal Medicine.”

Connor Showalter can be reached at connor.showalter@temple.edu.