Cutting back on fatty foods like cheeseburgers and fries reduces the risk of heart disease. So cutting way back is even better, right? Not necessarily, according to a report published this week in Circulation, a journal of the American Heart Association.

Dr. Linda Van Horn, co-author of the report, said researchers do not have enough data to say whether ultra-low-fat diets are generally better at fighting heart disease than moderately low-fat diets. Van Horn, a professor at Northwestern University Medical School, said her team reviewed all of the available studies on ultra-low-fat diets and the data doesn't warrant the AHA to take a more aggressive stance, she said.The American Heart Association recommends that less than 30 percent of a person's calories come from fat. An ultra-low-fat diet contains at most 15 percent of calories from fat.

The average American diet contains 34 percent of calories from fat. The 30 percent target translates to 67 grams of fat for a person who consumes about 2,000 calories per day. By way of reference, a Big Mac contains 31 grams of fat and a Whopper has 39 grams of fat.

Van Horn said some studies showed impressive results in reducing heart disease risk. However, questions remained because some studies had few participants, follow-up was limited, concerns persisted about long-term nutrient adequacy and it was unclear whether the benefits would be experienced by the general population.

Dr. Montaz Wassef, who works at the National Heart, Lung and Blood Institute in Maryland, said it would be unwise for the AHA to recommend a substantially lower fat intake.

"There isn't enough data to give a blanket recommendation for such a low-fat diet, and I don't think you can give a blanket recommendation," said Wassef, who was not associated with Van Horn's work. "People react differently."

Previous research has found that about one-third of the U.S. population may benefit from reducing fat intake below 30 percent, one-third would be unaffected and the final third could actually increase their risk of heart disease depending on genetic factors.