Impact of Asprosin and Neuregulin 4 on Metabolic Parameters, Anthropometric Indices and Body Composition After Laparoscopic Sleeve Gastrectomy

Asprosin and neuregulin 4 (NRG4) sit on opposing arms of adipose endocrine physiology. Asprosin is a fasting-induced, white adipose-derived glucogenic and orexigenic hormone that rises with adiposity and insulin resistance. NRG4 is a brown and beige adipose-derived, anti-lipogenic and hepatoprotective factor that falls with adiposity. Both have been examined separately after metabolic and bariatric surgery, but never in the same cohort, and existing surgical data cannot separate a weight-loss-dependent effect from an effect of the operation itself. Objectives: To quantify the change in fasting serum asprosin and NRG4 over twelve months after laparoscopic sleeve gastrectomy (LSG); to determine whether those changes are associated with metabolic improvement independently of weight loss; and to characterise their relationship with anthropometric indices and body composition.

Inclusion Criteria: * body mass index of at least 35 kg/m² regardless of the presence * absence or severity of obesity-related comorbidities * should be considered at 30-34.9 kg/m² in the presence of metabolic disease Exclusion Criteria: * revisional or emergency surgery * type 1 diabetes or insulin-treated type 2 diabetes * use within three months of a GLP-1 receptor agonist * dual GIP/GLP-1 receptor agonist * SGLT2 inhibitor or thiazolidinedione * systemic corticosteroid or immunosuppressive therapy * chronic liver disease of non-metabolic aetiology or cirrhosis * alcohol intake above 20 g/day in women or 30 g/day in men * estimated glomerular filtration rate below 60 mL/min/1.73 m² * FBN1-related connective tissue disorder * active or recent malignancy * untreated thyroid * adrenal or gonadal disorder * pregnancy or lactation * any device precluding bioelectrical impedance analysis * high-sensitivity C-reactive protein above 10 mg/L at baseline