Randomized Trial of Preoperative Diets Before Bariatric Surgery

Morbid obesity, defined as a body mass index (BMI) of \> 40 kg/m² or \> 35 kg/m² with obesity-related comorbidities, is a rapidly growing problem in the western society. In the United States, about 6 million people currently have a BMI of \> 40 kg/m² and another 10 million people have a BMI of \> 35 kg/m² with comorbidities. Worldwide, the incidence of morbid obesity has doubled and about 300 million people are now obese. In the Netherlands the prevalence is less disturbing but the incidence of morbid obesity is rising progressively to 1.5% of the total population. At this moment surgical therapy is the only treatment option for these patients that results in sufficient long-term weight loss. Non-surgical approaches, like low energy diets and behavior modification, are not successful in the long-term with respect to maintaining weight loss and decreasing obesity-related comorbidities. In order to increase weight loss and minimize complications a preoperative diet before bariatric has been advocated. However, the usual VLCD's are poorly tolerated by patients. In this study we aim to compare two preoperative diets in order to find the most suitable for this patient population.