Purpose: Sarcopenia is associated with higher mortality and morbidity in elective abdominal surgery, however the effect of body composition on emergency laparotomy (EL) remains insufficiently explored. This study evaluated the impact of 3D body composition, diagnosed from multiple lumbar 3 vertebral CT scans on EL surgical outcomes. Methodology: Retrospective analysis of ANZELA-QI patients treated at a tertiary Australia hospital was conducted. Sarcopenia was defined based on the lowest quartile for skeletal muscle radiodensity, Hounsfield Unit (HU). Multiple CT slices at the third lumbar vertebrae using a validated artificial intelligence segmentation model was used for body composition analysis. Results: A total of 297 patients were included (2018-2023; most common surgical procedures included colectomy (28.3%), adhesiolysis (20.5%) and small bowel resection (14.5%)). A total of 2844 CT slices were analysed, with a mean ± standard deviation of 9.6 ± 3.5 slices per patient. Sarcopenia, average radiodensity of L3 muscles (HU≤ 25.27), was significantly associated with age (76 vs 58 years; p < 0.001), increased length of stay (24 vs 14 days; p < 0.001), increased need of postoperative care in intensive care unit/high-dependency unit, severe complications (Clavien-Dindo ≥ 3) (p = 0.02) and higher level of care discharge disposition (p < 0.001). Additionally, sarcopenic patients had significant higher volumes of adipose tissue (Visceral Adipose Tissue p < 0.001; Subcutaneous Adipose Tissue p < 0.02). Conclusion: Sarcopenic patients are associated with higher fat volumes and significantly worse postoperative outcomes. CT-derived 3D lumbar body composition may be a future valuable tool in risk stratification for EL patients.