The best way to keep the weight off following a diet is to eat more protein like lean meat, low-fat dairy products and pulse
foods such as beans and lentils and less high glycemic index (GI) foods such as carbohydrate from white bread, white rice and
other refined starchy foods, said researchers conducting the world's largest dieting study; they also said with this regime you can
also eat until you are full without having to watch the calories and without putting weight on.
The researchers found that among adults who lost at least eight per cent of their body weight following a calorie-restricted diet, the ones who were most successful at keeping the weight off and least likely to drop out during the six months of follow up, were those who maintained a diet high in protein and low in refined carbohydrate (foods with a high glycemic index or GI).
Foods with a high glycemic index (GI) are those whose carbohydrate content is digested more quickly and therefore their end-product, glucose, enters the bloodstream more quickly. Foods with a low GI have carbohydrates that break down more slowly during digestion, so the glucose enters the bloodstream over a longer period of time.
Known as Diogenes, the large-scale random study, funded by a European Union grant of 14.5 million Euros (19 million US dollars) took place at eight European research centres and was led by Drs Thomas Meinert Larsen and Arne Astrup of the Faculty of Life Sciences (LIFE) at the University of Copenhagen. A paper on the work is published in the 25 November online issue of the New Endgland Journal of Meidicne, NEJM.
Larsen and colleagues also concluded that the official dietary recommendations in Europe are not enough to prevent obesity, and should be updated to reflect the latest research about the importance of proteins and carbohydrate for appetite control.
For the study, they enrolled 772 European families, among whom were 938 adults who were overweight, with a mean body mass index (BMI) of 34 kg/sq m. These were invited to complete an an eight week weight reduction program, where they limited calorie intake to 800 kcals a day and lost an average of 11 kg (just over 24 lbs).
The researchers then randomly assigned the 773 adults who completed the eight-week weight loss diet to one of five low-fat maintenance diets for six months. The point was to determine which of the five types of diet was most effective at preventing weight gain.
The five diet types were:
- Low protein (13% of calorie intake), high GI
- Low protein, low GI.
- High protein (25% of calorie intake), low GI.
- High protein, high GI.
- Following the current dietary recommendations with no special instructions about GI (the control group).
After the six month maintenance diet phase, the results showed that:
- 548 (71%) adults completed this second, maintenance diet phase of the study.
- More participants in the high-protein low-GI group completed this phase than in the low-protein high-GI group (26.4% and 25.6% respectively, compared to 37.4% in the controls; P=0.02 and P=0.01 for the respective comparisons).
- The average weight regain across all the groups was 0.5 kg.
- The poorest result was the low-protein high-GI diet: the only one to be linked to significant weight regain (average gain 1.67 kg, 95% confidence interval CI, ranged from 0.48 to 2.87).
- The weight regain was on average 0.93 kg (95% CI, 0.31 to 1.55) less for those on the high-protein diets than those on the low-protein diets (P=0.003), and 0.95 kg (95% CI, 0.33 to 1.57) less on those on low-GI compared to high-GI diets (P=0.003).
"In this large European study, a modest increase in protein content and a modest reduction in the glycemic index led to an improvement in study completion and maintenance of weight loss. "
The researchers also conducted another study involving the children of the families enrolled on Diogenes, where 45% of them were overweight. This is published in the journal Pediatrics and shows that of the overweight children who simply followed the same diet as their parents (they were not required to count calories or "go on a diet"), the group that followed a high protein low-GI diet had the most children who moved from overweight to normal weight.
In a statement, the researchers said that the Diogenes study results support the idea that the current dietary recommendations are not the best for preventing weight gain in overweight people.
They suggest a diet containing slightly more protein and low-GI foods "ad libitum" appears to be easier to follow and ensures slimmed down people keep the weight off. It also appears to result in a "spontaneous drop" in the prevalence of overweight among the children in families that follow such a regime.
"Diets with High or Low Protein Content and Glycemic Index for Weight-Loss Maintenance."
Thomas Meinert Larsen, Stine-Mathilde Dalskov, Marleen van Baak, Susan A. Jebb, Angeliki Papadaki, Andreas F.H. Pfeiffer, J. Alfredo Martinez, Teodora Handjieva-Darlenska, Marie Kunešová, Mats Pihlsgård, Steen Stender, Claus Holst, Wim H.M. Saris, and Arne Astrup, for the Diet, Obesity, and Genes (Diogenes) Project.
N Engl J Med, 2010; 363:2102-2113, Published online 25 November 2010
Additional source: University of Copenhagen.
Written by: Catharine Paddock, PhD