The World Health Organization projects that by 2015, approximately 700 million adults will be obese. The Diogenes Project is one of the largest projects worldwide targeting the obesity problem from a dietary perspective.
Diogenes, an acronym for “Diet, Obesity and Genes” is one of the largest projects worldwide targeting the obesity problem from a dietary perspective. The Diogenes Team, with Professor Wim Saris from the University of Maastricht as its Executive Director, has performed multi-disciplinary, multi-center international research by integrating studies of dietary, genetic, physiological, psychological and food technological factors.
This project has a total budget of €21 million, including €14.5 million of European Union funding, and includes 32 partners across Europe — both (academic) research institutes and private companies. Final results will be available later this year.
Saris proudly reports on the successful integration of disciplines in the Diogenes Project. All research lines, from basic genetics up to food application, were connected to a large dietary intervention study in 8 countries, which included whole families with overweight, obese, and normal weight members. A central data hub facilitated standardization of protocols and data collection, storage of (and access to) collected research data, and the rapid and detailed analysis of the results. Furthermore, a bio bank containing, for example, plasma, adipose tissue and isolated DNA, was established.
Pan-European weight loss study
A healthcare worker assesses a child’s health.
The primary focus of Diogenes was an investigation into the role of the Glycemic Index (GI) of carbohydrates and the role of high protein content in relation to satiety enhancement. “We considered the role of fat in relation to weight to be sufficiently known,” Saris explains.
In foods with a reduced amount of fat, carbohydrate and/or protein levels will be elevated. Literature reveals that both GI and protein could be promising dietary factors for weight control with potential for the food industry.
“Literature, however, is conflicting with respect to GI effects,” Saris adds. “Therefore, for the first time, we conducted an intervention trial with respect to the effectiveness of GI and protein in prevention of weight (re)gain in an ad libitum setting.”
Long-term
The Diogenes Team managed a large, long-term, randomized, parallel dietary intervention study in eight geographic centers, in which 763 participating adults were successfully enrolled after losing more than 8% of their weight during an eightweek low-calorie diet.
After the weight loss phase of the selected adults, 565 families (763 adults and 787 children) were enrolled in the intervention study and randomly distributed into five study groups — each following different diets, either high or low in protein and/or high or low in GI carbohydrates. The fifth diet, the control diet, was based on national guidelines for a healthy diet. Special attention was paid to minimizing the burden for the children and to the potential risks associated with a high protein diet for children, in particular, with respect to growth and metabolism.
Families
In two centers (Maastricht and Copenhagen), supermarkets set up for the study provided whole families with free food for the first six months. In the subsequent six months, the same subjects only received dietary advice and support. The other six centers provided families with six months of dietary advice and support only.
The supermarket dietary intervention had been validated to allow a strict compliance to a targeted diet composition with a concomitant allowance of variable energy intake. All food items in the supermarkets were commercially available and barcoded. A dietician scanned the barcodes of all the chosen items in order to monitor macronutrient composition of the diet and assisted in altering the selection to meet the prescribed diet composition.
The calculated energy content of the chosen groceries was not made known to the subjects. Outcome measures like weight (regain) and (changes in) BMI, waist circumference, waist/hip circumference ratio, body fat (%), risk factors of type 2 diabetes and cardiovascular disease and satiety factors were determined. Physical activity was registered.
High protein content favorable
Although complete analysis of the results is still pending, interesting results already have been obtained from the two well-controlled supermarket centers.