Hypothalamic integrity is necessary for sustained weight loss after bariatric surgery: A prospective, cross-sectional study. Effects of bariatric surgery on weight, hormones/glucose, microbiota, physical/mental health in hypothalamic and common obesity.

The hypothalamus is the main integrator of peripheral and central signals in the control of energy homeostasis. Its functional relevance for the effectivity of bariatric surgery is not entirely elucidated. Studying the effects of bariatric surgery in patients with hypothalamic damage might provide insight. In our study we compare patients with hypothalamic obesity (HO) vs patients with common obesity (CO). HO individuals lost significantly less weight after bariatric surgery than CO-participants. After a mixed meal, satiety and abdominal fullness tended to be lowest in HO-surgery and did not correlate with levels of the gut hormones GLP-1 or PYY. Levels of PYY and GLP-1 (20,975 ± 2893 pmol/l/h vs. 13,060 ± 2357 pmol/l/h, p = 0.009) were significantly higher in the HO-surgery vs. CO-surgery group. Abundance of Enterobacteriaceae and Streptococcus was increased in feces of HO and CO after bariatric surgery. Comparing HO patients with lean-controls revealed an increased activation in insula and cerebellum to viewing high-caloric foods in left insula and cerebellum in fMRI. Hypothalamic integrity is necessary for the effectiveness of bariatric surgery in humans. Peripheral changes after bariatric surgery are not sufficient to induce satiety and long-term weight loss in patients with hypothalamic damage.