TURSDAY JULY 17 (foodconsumer.org) -- Once again a trial proved that weight loss is not easy: people on three dietary programs with intake of calories tightly controlled and dieters receiving consultation from researchers yielded only a loss of no more than 10 pounds in a 2-year period.

Among the three diets, a low carbohydrate (Atkins diet), a low fat diet and a Mediterranean diet, low carb diet apparently did the best in terms of weight loss.  The down side with the low fat diet is that less than 80 percent people could stick to the dietary program while other diets retained much higher percentages of dieters.

The trial was partially funded by the Atkins Research Foundation, conducted by Dr. Iris Shai at Ben-Gurion University of the Negev in collaboration with Harvard University and the University of Leipzig, German and the University of Western Ontario, Canada and the results were published in the New England Journal of medicine. Researchers claimed they did not get paid nor received gifts from the sponsors.

The low fat diet with fat accounting for 30 percent of 1500 kcal daily for women and 1800 for men was recommended by the American Heart Association. The Mediterranean diet contained high vegetables and some poultry and fish, but without beef and lamb and no more than 35 percent of 1500 kcal/1800 kcal for women/men from fat, mostly olive oil and some nuts.   The low carbohydrate diet was largely the same as Atkins diet with high fat, high protein and dietary cholesterol.   All diets were calorie-restricted. Low carb dieters were allowed to eat as much as they wanted to, but they had similar intake of calories with other types of dieters.

All dieters ate lunch prepared by the research team and had breakfast and dinner at home.

In the 2-year trial, the three diets were tested in 322 moderately obese men and women.   At the end of study, the low fat diet kept 90 percent of participants compared to 85 percent for the Mediterranean diet and 78 percent for the low-carbohydrate dieters.  

Men and women on the low fat diet lost 6.5 pounds compared to 10 pounds in those on the Mediterranean diet and 10.3 pounds in those on the low-carbohydrate diet during the 2-year trial.

All participants experienced improvement in inflammatory and liver function biomarkers.   But those who were on the low carb diet reduced the total cholesterol to HDL ratio by 20 percent compared to 12 percent in those who were on the low fat diet. The low carbohydrate diet also increased the good cholesterol by 20 percent and reduced 14 % in triglycerides.

Among those who were diabetic, the low-fat diet increased the fasting glucose levels by 12 mg/dL, while the Mediterranean diet lowered fasting glucose levels by 33 mg/dL.

The biggest weight loss occurred during the first six months and those on the low fat diet and the Mediterranean diet lost about 10 pounds while those on the low-carb lost 14 pounds.

At the end of the two-year trial, however, all dieters regained some weight.   The low fat dieters had a net loss of six pounds while the low carbohydrate and Mediterranean dieters lost about 10 pounds.

The effect of the diets on weight loss also depended on the gender.

Men did better on the low carbohydrate diet losing 11 pounds than those on the Mediterranean diet losing 9 pounds.   Women did better on the Mediterranean diet losing about 14 pounds than those on low carbohydrate plan losing about only 5 pounds.

The low carb diet has been demonstrated in previous studies to be able to help dieters to lose weight quickly.   The problem with this diet is that the nutrition profile is not as healthy as desired and many people would experience many types of health conditions.  

The press release by American Associates, Ben-Gurion University of the Negev did not address the side effects of all three diets on the participants.  The trial report revealed some data on biomarkers, but no health experience was recorded.   The highest drop-out rate in the low carbohydrate group observed in the trial may suggest that the diet was least popular among the dieters.

The trial did not seem to have considered the contribution of physical activity in the three diet groups to the overall weight loss effect. Physical activity is also important when it comes to weight loss and improvement of biomarkers for cardiovascular health.  Lack of this type of data discounted the accuracy of the data on the effect of the three diets on weight loss.

The results of the trial may not be applicable to people who live in a non-trial setting.   In the trial, participants followed planned diet programs carefully and received consultation on nutrition and other issues from the researchers.

A health observer affiliated with foodconsumer.org said that the trial essentially confirmed previous studies showing that a low carb diet (Atkins diet) is effective at helping people lose weight in a short term AND fewer people could keep their pounds off for a long term because they could not stick to the dietary program for a long term.