Objective:　For　locally　advanced　rectal　cancer,　total　neoadjuvant　therapy　can　improve　the　pathologic　complete　response　rate.　However,　total　neoadjuvant　therapy-related　adverse　events　and　postoperative　complications　remain　significant　challenges.　Methods:　A　restricted　cubic　spline　model　was　used　to　analyze　the　relationship　between　visceral　adipose　tissue　and　total　neoadjuvant　therapy-related　adverse　events,　intraoperative　parameters,　and　postoperative　complications.　In　addition,　receiver　operating　characteristic　curves　combined　with　the　Youden　index　were　used　to　stratify　patients　with　locally　advanced　rectal　cancer.　Results:　This　multicenter,　real-world　retrospective　study　analyzed　data　from　739　patients　with　locally　advanced　rectal　cancer　who　underwent　total　neoadjuvant　therapy　combined　with　standard　total　mesorectal　excision.　The　results　revealed　a　U-shaped,　nonlinear　association　between　baseline　visceral　adipose　tissue　and　both　total　neoadjuvant　therapy-related　adverse　events　and　postoperative　complications　(All　P　for　nonlinear　＜　.05),　with　both　low　visceral　adipose　tissue　and　visceral　obesity　linked　to　an　increased　risk　of　perioperative　complications.　On　the　basis　of　the　restricted　cubic　spline　and　receiver　operating　characteristic　curves,　patients　with　locally　advanced　rectal　cancer　were　classified　into　a　low　visceral　adipose　tissue　group　(＜=　29.5　cm(2)),　a　normal　visceral　adipose　tissue　group　(29.5　similar　to　105　cm(2)),　and　a　visceral　obesity　group　(＞=　105　cm(2)).　In　the　low　visceral　adipose　tissue　group,　visceral　adipose　tissue　loss　during　total　neoadjuvant　therapy　was　associated　with　more　perioperative　complications,　whereas　visceral　adipose　tissue　accumulation　correlated　with　a　reduction　in　perioperative　complications　(P　for　nonlinear　＞0.05).　Moreover,　in　the　visceral　obesity　group,　any　change　in　visceral　adipose　tissue　(whether　accumulation　or　loss)　was　associated　with　more　perioperative　complications　(P　for　nonlinear　＜0.05).　Conclusion:　Monitoring　visceral　adipose　tissue　via　computed　tomography　may　serve　as　a　novel　biomarker　for　predicting　total　neoadjuvant　therapy-related　adverse　events　and　postoperative　complications　in　patients　with　locally　advanced　rectal　cancer.　(c)　2025　Elsevier　Inc.　All　rights　are　reserved,　including　those　for　text　and　data　mining,　AI　training,　and　similar　technologies.