Background Increased fructose intake has been associated with metabolic consequences such as impaired hepatic lipid metabolism and development of nonalcoholic fatty liver disease (NAFLD). Objectives The aim of this study was to investigate the role of fructose in glucose and lipid metabolism in the liver, heart, skeletal muscle, and adipose tissue. Methods Ten healthy subjects (age: 28 ± 19 y; BMI: 22.2 ± 0.7 kg/m2) underwent comprehensive metabolic phenotyping prior to and 8 wk following a high-fructose diet (150 g daily). Eleven patients with NAFLD (age: 39.4 ± 3.95 y; BMI: 28.4 ± 1.25) were characterized as “positive controls.” Insulin sensitivity was analyzed by a 2-step hyperinsulinemic euglycemic clamp, and postprandial interorgan crosstalk of lipid and glucose metabolism was evaluated, by determining postprandial hepatic and intra-myocellular lipid and glycogen accumulation, employing magnetic resonance spectroscopy (MRS) at 7 T. Myocardial lipid content and myocardial function were assessed by 1H MRS imaging and MRI at 3 T. Results High fructose intake resulted in lower intake of other dietary sugars and did not increase total daily energy intake. Ectopic lipid deposition and postprandial glycogen storage in the liver and skeletal muscle were not altered. Postprandial changes in hepatic lipids were measured [Δhepatocellular lipid (HCL)_healthy_baseline: −15.9 ± 10.7 compared with ± ΔHCL_healthy_follow-up: −6.9 ± 4.6; P = 0.17] and hepatic glycogen (Δglycogen_baseline: 64.4 ± 14.1 compared with Δglycogen_follow-up: 51.1 ± 9.8; P = 0.42). Myocardial function and myocardial mass remained stable. As expected, impaired hepatic glycogen storage and increased ectopic lipid storage in the liver and skeletal muscle were observed in insulin-resistant patients with NAFLD. Conclusions Ingestion of a high dose of fructose for 8 wk was not associated with relevant metabolic consequences in the presence of a stable energy intake, slightly lower body weight, and potentially incomplete absorption of the orally administered fructose load. This indicated that young, metabolically healthy subjects can at least temporarily compensate for increased fructose intake. This trial was registered at www.clinicaltrials.gov as NCT02075164.

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Background In severe obesity, hypogonadism in men and androgen excess in women are frequently observed. Sex hormones play an important role in body composition and glucose and lipid metabolism. However, whether pre-operative gonadal dysfunction impacts weight loss after bariatric surgery is not fully known. Methods A total of 49 men and 104 women were included in a retrospective analysis. Anthropometric characteristics, glucose and lipid metabolism, and androgen concentrations were assessed pre-operatively and 17.9 ± 11 or 19.3 ± 12 months postoperatively in men and women. Men with (HYPO male) and without (controls: CON male) pre-operative hypogonadism, as well as women with (HYPER female) and without (controls: CON female) pre-operative hyperandrogenemia, were compared. Results In men, pre-operative hypogonadism was present in 55% and linked to a higher body mass index (BMI): HYPO male 50 ± 6 kg/m 2 vs. CON male 44 ± 5 kg/m 2 , p = 0.001. Bariatric surgery results in comparable changes in BMI in HYPO male and CON male − 16 ± 6 kg/m 2 vs. − 14 ± 5 kg/m 2 , p = 0.30. Weight loss reversed hypogonadism in 93%. In women, androgen excess was present in 22%, independent of pre-operative BMI: CON female 44 ± 7 kg/m 2 vs. HYPER female 45 ± 7 kg/m 2 , p = 0.57. Changes in BMI were comparable in HYPER female and CON female after bariatric surgery − 15 ± 6 kg/m 2 vs. − 15 ± 5 kg/m 2 , p = 0.88. Hyperandrogenemia was reversed in 61%. Conclusions Besides being frequently observed, hypogonadism in men and androgen excess in women have no impact on postsurgical improvements in body weight and glucose and lipid metabolism. Weight loss resulted in reversal of hypogonadism in almost all men and of hyperandrogenemia in the majority of women.

Purpose In our centre, specialized high dose multivitamin supplementation designed to meet the needs of patients after gastric bypass surgery is routinely recommended in the early postoperative period. The aim of the present study was to analyse whether iron supplementation prescribed in clinical practice is sufficient in both sexes and whether multivitamin supplementation standardized for women might potentially lead to iron overload in men. Materials/Methods This was a retrospective study covering the period up to 36 months after bariatric surgery. Three groups were compared (men, premenopausal and postmenopausal women). The iron status was evaluated employing serum ferritin concentrations. Results A total of 283 patients who had at least one follow-up visit between January 2015 and April 2018 at a specialized academic outpatient centre were included (71 men, 130 premenopausal women, 82 postmenopausal women). Thirty-six months after surgery, 33.3%, 68.4% and 54.5% of the men, pre- and postmenopausal women, respectively, were iron deficient. The preoperative prevalence of excess ferritin levels was 13.7% in premenopausal, 3.0% in postmenopausal women, 5.7% in men and declined in the following months. Conclusion Iron deficiency is very common after gastric bypass surgery, and even high dosages of multivitamin and mineral supplements might not be sufficient to prevent the development of iron deficiency. Men, pre- and postmenopausal women differ in their prevalence of iron deficiency which demands adapted iron dosage regimens based on the sex and the age. Iron overload is rare in all observed groups and highest in premenopausal women. Graphical abstract

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