Data indicate a high prevalence of micronutrient deficiencies in morbidly obese subjects. Based on these results, we strongly recommend a systematic assessment of the micronutrient status in all candidates for bariatric surgery.

In comparison with nonobese control subjects, severely obese patients display a marked increase in hedonic hunger that is not observed in patients who have undergone gastric bypass surgery, suggesting that the operation normalizes excessive appetite for palatable foods, which may be an important pathophysiologic feature of severe obesity.

Data show a marked reduction of the hedonic drive to consume palatable food and beneficial changes in dietary habits characterized by an increased intake of protein-rich foods and vegetables and a reduced consumption of sugar-containing snacks and beverages after RYGB surgery. Based on these findings, it can be speculated that the reduction of the hedonic drive to consume palatable foods induced by RYGB surgery helps severely obese patients to establish healthier dietary habits.

Our data indicate that bariatric surgery, irrespective of the specific kind of procedure used, reverses most of the metabolic alterations associated with obesity and suggest profound changes in gut microbiome-host interactions after the surgery. This trial was registered at clinicaltrials.gov as NCT02480322.

Data provide evidence for an altered brain activity pattern in severely OB women and suggest that RYGB surgery and/or the surgically induced weight loss reverses the obesity-associated alterations.

Collectively, data clearly point to distinct changes in dietary habits after bariatric operations which markedly differ between gastric bypass and gastric banding patients. Overall, it is tempting to conclude that gastric bypass operations lead to a healthier and a more balanced diet than gastric band implantations.

Results indicated differential changes in exercise performance, with the relative but not the absolute peak performance being improved after massive weight loss. Interestingly, anaerobic exercise tolerance was markedly improved after surgery.

Proximal Roux-en Y gastric bypass (RYGB) representing the most frequently performed bariatric procedure yields a weight loss failure rate of around 20 %. In order to reduce failure rates, we established a novel distal RYGB variant characterized by a very long alimentary (Roux) limb and a short common channel. Up to 5 years, follow-up data (complication rates, weight loss, nutritional/metabolic changes) of the first 355 patients (mean ± SD preoperative age, 41.4 ± 10.8 years; BMI, 48.5 ± 11.5 kg/m(2)) who underwent the novel Distal Very Long Roux-en Y Gastric Bypass (DVLRYGB) were analysed. Overall follow-up rate was 98.9 %, mean follow-up time 1.6 ± 1.4 years. Limb lengths were as follows: common channel 76 ± 7 cm, biliopancreatic limb 79 ± 14 cm, and alimentary (Roux) limb 604 ± 99 cm. The operation was performed laparoscopically in 95.2 % of the cases. Thirty-day mortality was zero; major and minor complication rate was 4.5 % and 10.4 %, respectively. Average excess weight loss (EWL) was >74 % 3, 4, and 5 years after the operation and failure rate defined by an EWL < 50 % remained < 6 %. Annually blood measurements revealed a relatively low incidence rate of severe nutritional deficiencies, but mild anaemia and hypoproteinemia were frequently observed. Laparoscopic revision with a proximalization of the lower anastomosis was required in 4 (1.1 %) patients. Data indicate that our DVLRYGB leads to excellent weight loss results. Furthermore, within the setting of a structured multidisciplinary follow-up program, the incidence of severe malnutrition states was relatively low.