Obesity treatment

Our research focusses on patients with morbid obesity. Bariatric surgery is a valid option for people with morbid obesity who have already tried everything to lose weight. Every year in the Netherlands, approximately 12,000 people with morbid obesity undergo bariatric surgery.

Vitalys, part of Rijnstate, is one of the largest clinics in the Netherlands for bariatric surgery. In this clinic, more than 1,300 operations are performed per year. Rijnstate, Vitalys and Wageningen University & Research work together through the Alliance Nutrition and Healthcare on optimal nutritional care for these patients - before and after the procedure.

Bariatric surgeon Eric Hazebroek was appointed special professor of Nutrition and Obesity Treatment at Wageningen University & Research in February 2019. Under his supervision, various PhD candidates work on several studies in the project 'Nutrition & Obesity Treatment'. We focus on four areas of research, namely 1) Nutritional status after bariatric surgery, 2) Bodyweight loss after bariatric surgery 3) Obesity related comorbidities (sleep apnea) and 4) Improving surgical techniques.

Nutritional status after bariatric surgery

Each bariatric operation alters the anatomy and physiology of the gastrointestinal tract to a greater or lesser extent. As a result, patients have an increased risk of nutritional deficiencies which may lead to anemia, osteoporosis or malnutrition.

Optimal vitamin supplementation: As part of the VITAAL studies, the optimal composition of multivitamins for patients who have undergone gastric bypass surgery was studied. Similar studies are now being performed in patients who had sleeve gastrectomy. Together with researchers at Catharina Hospital, Franciscus Gasthuis & Vlietland and OLVG, we are looking how to improve adherence to oral supplements. In addition, alternative methods of vitamin supplementation are studied.

Pregnancy: The NEWBIE study is a multicenter cohort study in which women who become pregnant after bariatric surgery are followed. This study is performed at Rijnstate Hospital, Hospital Gelderse Vallei and the Maxima Medical Center. In this study, nutritional status and its influence on the course of pregnancy and the development of the unborn child are investigated.

Preoperative weight loss: Weight loss prior to surgery can lead to a reduction in liver size and decrease in visceral adipose tissue (abdominal fat). This may have a positive effect on the feasibility of the operation and long-term weight loss. In the PREBA study, patients are randomly assigned to a diet group and a control group. The diet group follows a 'low-caloric diet' 2 weeks prior to surgery.

Eetscore: This study investigates to which extent the Nutrition Questionnaire Eetscore is applicable to bariatric patients. The quality of nutrition before and after bariatric surgery is also investigated.

Weight loss after bariatric surgery

The main cause of weight loss after bariatric surgery is obviously that people will eat less. However, the mechanisms behind successful weight loss and less favorable results are not fully understood. Unravelling these mechanisms is important to improve future treatment.

Food preference: In collaboration with Prof. Dr. Marco Bueter, surgeon and professor at the University of Zurich, measurements with a specially developed 'drinkometer' are performed in gastric bypass patients. Pre- and postoperatively, patients are offered different types of drinks that vary in fat and sugar content. The drinkometer then indicates how much and how quickly they consume it. This study also investigates taste change before and after a bariatric procedure with data from a taste database developed by Wageningen University & Research.

Gastric emptying: Research into gastric emptying after bariatric surgery is done in collaboration with Wageningen University & Research and the Department of Nuclear Medicine and Radiology of the Rijnstate Hospital. The 3T-MRI scanner of Hospital Gelderse Vallei is also used. Together with Dr Paul Smeets (WUR), the speed of food passage through the reduced stomach, the gastric pouch, is measured with an MRI scan. This measurement is done in people who have lost a lot or very little weight after a gastric bypass. The study is repeated in patients who have undergone gastric sleeve surgery.

Gastrointestinal complaints: Bariatric surgery changes the anatomy of the gastrointestinal tract, leading to abdominal pain in almost one third of patients. This may be due to a reduced release of digestive enzymes and the more frequent occurrence of lactose intolerance and bacterial overgrowth. However, abdominal pain can also have many other causes. The QUINT study, a large study of abdominal complaints and dietary intake 5 years after surgery, should provide more clarity. Participants complete questionnaires about abdominal and other complaints before and after surgery. The framework of the BARICO study, a collaboration between TNO and Radboud University, is used to investigate the relationship between abdominal complaints and changes in the microbiome in the gastrointestinal tract.

Obesity is an important risk factor for developing obstructive sleep apnea, a serious condition characterized by periodic breathing stops during sleep, with increased cardiometabolic risks. After bariatric surgery, most patients will be cured from their sleep apnea as a result from the massive weight loss. In the POPCORN study, we will evaluate how we can monitor our patients safe and cost-effectively at the time of surgery. We now have included more than 1300 patients from 7 participating hospitals. This large cohort provides a perfect platform for future studies to investigate the cardiometabolic effects of sleep apnea and how this relates to body weight regulation long after the operation.

Improving surgical techniques

For many patients with morbid obesity, bariatric surgery is the most effective treatment. However, about 25% of patients have an insufficient wight loss result after a few years.

Preventing weight regain: In several studies, we investigate the effects of adjustments to the gastric bypass, such as lengthening and narrowing the stomach pouch or placing a silicone ring around the stomach pouch. Recently, the RING study was started to investigate if placement of a ring around the gastric sleeve prevents weight gain after gastric sleeve surgery. In the UPGRADE study, we investigate if modifications to gastric pouch configuration influence weight loss outcomes after gastric bypass surgery.

Dumping syndrome: Improved surgical techniques may also reduce the risk of so-called 'dumping syndrome', a problem that occurs mainly after a gastric bypass. It is characterized by complaints such as palpitations, dizziness, feeling full and abdominal pain. Placing a ring around the gastric pouch can slow down the gastric emptying rates and potentially reduce these symptoms.

Current key projects

Key publications