WASHINGTON, Jan 5 (AFP) - US researchers have found that four fashionable diets -- including the Atkins low carb eating regime and the Ornish vegetarian diet -- have only limited success in reducing weight, a top medical journal reported.
Weight loss depends more on sticking with a diet than the type of diet, according to the team from the Tufts-New England Medical Center in Boston. The researchers found that most people could not maintain a diet for a long period, the Journal of the American Medical Association (JAMA) reported.
"All four diets resulted in modest statistically significant weight loss at one year, with no statistically significant differences between diets," said the researchers, who were led by Michael Dansinger at Tufts.
The one year trial of 160 overweight or obese adults aged 22 to 72 years concentrated on the much-vaunted Atkins diet, the Ornish method restricting fat, Weight Watchers, which restricts portions and calorie intake and the Zone diet which requires the eating of food in set combinations.
All of those in the test had problems with hyper-tension, high cholesterol or diabetes.
"Popular diets have become increasingly prevalent and controversial," said the report.
"Many popular plans depart substantially from mainstream medical advice, and the effectiveness and safety of these diets have been questioned. Data regarding the relative benefits, risks, effectiveness, and sustainability of popular diets have been limited."
The new trial put 40 people on each diet and after two months of "maximum effort" the weighty guinea pigs were allowed to choose their own level of adherence.
The researchers found that the average weight loss at one year was 4.6 pounds (2.08 kilos) for Atkins, 7.1 pounds (3.2 kg) for Zone, 6.6 pounds (three kg) for Weight Watchers and 7.3 pounds (3.3kg) for Ornish.
"In each diet group, approximately 25 percent of the initial participants sustained a one-year weight loss of more than five percent of initial body weight and approximately 10 percent of participants lost more than 10 percent of body weight," Dansinger and the other authors wrote.
"We found that a variety of popular diets can reduce weight and several cardiac risk factors under realistic clinical conditions, but only for the minority of individuals who can sustain a high dietary adherence level."
They said that none of the diets produced "satisfactory adherence rates".
"The higher discontinuation rates for the Atkins and Ornish diet groups suggest many individuals found these diets to be too extreme."
The authors suggested diets should be broader to "to better match individual patient food preferences, lifestyles, and cardiovascular risk profiles."
01/05/2005 15:53 GMT - AFP