Surgical Nutrition — Screening, GLIM, ERAS Feeding, Immunonutrition, Refeeding, Fistula

The depleted patient undoes the operation — so learn surgical nutrition as a timed sequence: screen every admission with a validated tool, diagnose and grade with GLIM, optimise before the knife with prehabilitation and carbohydrate discipline instead of prolonged fasting, feed early and enterally after surgery, reserve parenteral nutrition for the severely malnourished and the gut that cannot be used, add combination immunonutrition for elective gastrointestinal cancer, and watch every refeeding step for the phosphate fall that announces the syndrome.^{[1][6][36][48][53][65][70]}

A 68-year-old man with colon cancer and 12% unintentional weight loss screens positive on NRS-2002 and awaits colectomy. The examiner will ask which screening tool to trust and why it is still insufficient alone, how GLIM grades his depletion, what prehabilitation buys a frail patient, whether carbohydrate loading changes his insulin resistance or his comfort, how short his fast should be, when oral feeding resumes, whether immunonutrition applies, and what his day-2 phosphate fall means. This page answers each question with every number taken from the paper named beside it.^{[3][6][26][22][18][36][58][65]}

Screening — Find Risk First

Screen first, diagnose second — that two-step order is the whole architecture, and the bedside test to reach for is MUST: in the 16-study, 5695-participant network meta-analysis against Subjective Global Assessment, MUST had the highest overall accuracy (sensitivity 86%, 95% CI 75-93%; specificity 89%, 95% CI 83-93%), with the Nutritional Risk Index matching sensitivity (relative 0.93) but losing specificity (relative 0.75).^[3] Yet the same paper withholds the trigger finger: predictive accuracy is likely insufficient to justify optimisation without additional assessment — a positive screen buys a dietitian review, not a prescription.^[3] The ward alternative validates nearly as well: NRS-2002 carries 88% sensitivity and 92% specificity against geriatrician assessment, with positive and negative predictive values of 87% and 92% and test-retest kappa of 0.956.^[4] In colorectal cancer specifically, every common screen — SGA and patient-generated SGA, prognostic nutritional index, NRI, MUST, NRS-2002, nutrition risk score, albumin and prealbumin — has effectively predicted postoperative outcome, so choose by mode of assessment, efficiency, and parameters rather than by brand loyalty.^[5]

Two humility notes close the section. First, screens miss GLIM-defined malnutrition: across tools, sensitivity against GLIM runs only 50-82%, lower than specificity — a negative screen in a depleted-looking patient deserves a second look.^[7] Second, the EFFORT trial (medical inpatients at nutritional risk) showed individualised nutritional support improved survival against standard hospital food, and its authors argue for systematic admission screening regardless of condition followed by assessment and targeted support — the principle generalises to surgery even though the trial population was medical.^[76]

GLIM — Diagnose and Grade

GLIM diagnoses in two steps: screen for at-risk status with any validated tool, then assess for diagnosis and severity grading.^[6] The criteria are five — three phenotypic (non-volitional weight loss, low body mass index, reduced muscle mass) and two etiologic (reduced food intake or assimilation, inflammation or disease burden) — and diagnosis requires at least one of each.^[6] Severity grades on phenotypic metrics as Stage 1 (moderate) versus Stage 2 (severe), while the etiologic criteria guide intervention and expected outcomes across four etiology-related categories.^[6]

Surgical numbers give the criteria weight. Among preoperative IBD patients, 42% met GLIM (34% Crohn's, 60% ulcerative colitis), with inflammation present in 51% even without intake reduction — which is exactly why GLIM out-detects ESPEN-2015 in this population.^[7] Among gastrointestinal-surgery candidates, GLIM malnutrition ran 32.3% with severe disease predominant at 21.2%, half the ward carried NRS-2002 risk (50.2%), nutritional risk multiplied GLIM-malnutrition odds nearly sixfold (OR 5.791), and cancer surgery doubled them (OR 2.068).^[8] Across hospitals, GLIM prevalence spans 16-80% by population — a spread that reflects case-mix, not criterion failure — with satisfactory sensitivity and specificity and low-to-high agreement against other methods.^[10]

Three technical points for the viva. Muscle mass is the least-assessed phenotypic criterion: measure or estimate it with DXA, CT, or BIA where available, anthropometry and physical examination where not, using ethnic- and sex-specific cutoffs — but never substitute muscle function for muscle mass, though function still belongs in the full assessment once malnutrition is diagnosed.^[9] The literature base is broad but uneven: only 57% of studies applied all five criteria, with low BMI the commonest phenotypic marker and intake plus inflammation the commonest etiologic ones.^[12] And the criteria began as expert opinion, so validation and reliability testing across sectors and populations remains the standing instruction.^[13] The 2025 five-year update consolidates rather than revises: 400-plus reports feeding 10 systematic reviews with meta-analyses support strong construct and predictive validity, no changes to weight-loss, BMI, or intake criteria are proposed, clinical judgement may carry the inflammation criterion, and the open fronts are ICU adaptation, intake-criterion support, and malnutrition in obesity — with unanimous working-group agreement.^[11]

Sarcopenia & Frailty — the Exam's Risk Multipliers

Frailty is depleted reserve against stressors; sarcopenia is low muscle mass with poor function — and frailty appears to outperform traditional anaesthetic and surgical risk scores for complications, stay, institutionalisation, and mortality.^[14] After gastrectomy in older patients, frailty predicted hospital mortality (OR 3.96) and sarcopenia pooled at OR 3.12 for adverse outcomes with zero heterogeneity — quote both numbers, then admit the base is eight studies deep.^[15] After colorectal-cancer surgery, sarcopenia added 1.46 days of stay and nearly tripled 30-day mortality (2.8% versus 1.0%, RR 2.74) — at low to very-low certainty, which must travel with the numbers.^[16] Preoperative sarcopenia, frailty, and possible malnutrition also predict postoperative delirium, so all three belong in the targeted preoperative assessment — while delirium management itself stays fenced to its owner topic.^[17]

Fasting — Stop Starving the List

The 2026 international consensus holds the solids line but liberalises the rest: keep current practice for solid food and non-clear liquids, encourage clear liquids until 2 hours before anaesthesia or sedation, implement institutional protocols allowing even more liberal intake inside 2 hours, permit gum or sweets until transfer, and resume drinking and eating as soon as able after the operation.^[18] The reason is harm, not comfort alone: prolonged fasting, especially from clear liquids, threatens wellbeing, glucose metabolism and inflammatory response, bowel recovery, and muscle strength.^[18] The implementation gap is old: ASA guidance since 1999 says healthy non-pregnant patients fast six hours from solids and two hours from liquids, yet wards still write blanket nil-by-mouth after midnight regardless of patient, procedure, or list order.^[19] Audit fasting times first; the protocol, not the ad-hoc sip, is the fix.

Carbohydrate Loading — Insulin Yes, Comfort Maybe, Infection Humility

The regimen is a lightly sweetened clear liquid, usually about 12% carbohydrate predominantly as maltodextrin, given up to 2 hours before surgery inside an ERAS programme aimed at shorter stay and fewer complications.^[20] The trial-tested version is concrete: 50 g of maltodextrin at 10 PM the night before plus 25 g two hours before induction, against a control fast of at least 6 hours.^[21] In living liver donors that regimen halved perioperative insulin resistance by HOMA-IR with better glycaemic control, less nausea and vomiting, earlier soft-diet tolerance, and earlier bilirubin normalisation — while complications, inflammatory markers, and length of stay did not move.^[21] The mechanism story is coherent: surgical stress and fasting drive insulin resistance through altered mitochondrial function, resistance raises morbidity dose-dependently, and loading attenuates resistance, minimises protein loss, and preserves postoperative muscle function.^[25]

The network meta-analysis (58 trials, 4936 patients) quantifies and humbles in the same paragraph: both low-dose (mean difference -3.25) and high-dose (mean difference -2.57) loading associate with less postoperative insulin resistance versus placebo or water, and low-dose loading associates with fewer postoperative infections versus fasting (odds ratio 0.42) — yet there is no evidence that loading alleviates patients' discomfort.^[22] The ERAS evaluation agrees on satisfaction and wellbeing without added perioperative complications, with the strongest signal in abdominal surgery.^[23] And the boundary is day surgery: across 6 randomised trials and 411 patients, loading showed no significant benefit over fasting or placebo for thirst, hunger, nausea and vomiting, fatigue, pain, or insulin resistance.^[24] Prescribe loading for major abdominal surgery within ERAS; expect metabolic benefit, do not promise comfort, and keep the infection finding as association with large uncertainty rather than proof.^[22][25]

Prehabilitation — Nutrition Inside the Package

Prehabilitation is a diagnosis-to-surgery process of exercise, nutrition, psychological, and respiratory interventions that builds functional capacity and physiological reserve to withstand surgical stressors, improve outcomes, and speed recovery — and agreeing that definition is the field's first standardisation step.^[26] The umbrella review of 55 systematic reviews sets the certainty gradient: moderate-certainty functional-recovery gains for cancer-surgery patients, but only low to very-low certainty that nutritional prehabilitation reduces complications, mortality, or stay — with optimal selection, design, and duration still undetermined.^[27] The BMJ component network meta-analysis (186 trials, 15684 participants) puts numbers on the gradient: isolated nutritional prehabilitation most likely cuts complications (odds ratio 0.62, very-low certainty) and shortens stay by about a day (-0.99 days, very-low certainty), combined exercise plus nutrition shortens stay (-1.22 days, moderate certainty), and exercise plus nutrition are the components most likely to improve every critical outcome.^[28]

Two populations sharpen the prescription. After oesophagectomy and gastrectomy, any nutrition-containing prehabilitation cut any-complication risk by 23%, driven by multimodal programmes (RR 0.78) with unimodal nutrition alone non-significant, and trimmed stay by 0.77 days — statistically real but clinically slight.^[29] In frail, older, high-risk major-abdominal surgery (median age 74), multimodal prehabilitation cut stay by 1.07 days, severe complications by up to 44% (OR 0.56), and added 40 metres to 6-minute walk distance — enough to encourage prehabilitation in this group while demanding better trials.^[30] The relationship with ERAS is complementary, not competitive: prehabilitation builds reserve before surgery so enhanced recovery can spend it after, because recovery begins preoperatively rather than passively.^[31]

Preoperative Nutrition Therapy — Target the Depleted

Cochrane GI 2024 (16 randomised trials, 19 comparisons, 2164 mixed nourished-and-malnourished participants, most outside ERAS, 14 at high risk of bias) is an uncertainty verdict: parenteral, enteral, immune-enhancing, and standard oral supplements each have uncertain effects on complications and stay.^[32] The one signal that survives sensitivity analysis is targeting: standard oral supplements probably reduce infections in weight-losing or malnourished participants (RR 0.58, 2 trials, 184 participants).^[32] The malnourished-patient meta-analysis (15 trials, 3831 patients) is more generous: support cut infectious complications (RR 0.58) and non-infectious ones (RR 0.74) and shortened stay by 2.64 days, with immune nutrition beating standard nutrition on infections (RR 0.75) — but hospital costs and mortality did not move.^[33] High-protein oral supplements (at least 20% energy from protein) in cancer patients reduced complications and stay without shifting readmissions or mortality.^[34] And the prescription extends past discharge: post-discharge ONS with dietary advice after gastric-cancer surgery improved nutritional outcomes, preserved skeletal muscle, aided chemotherapy tolerance, and eased fatigue and appetite loss.^[35]

Early Feeding — the Postop Default

Lewis 2001 asked whether starvation after gastrointestinal surgery helps, and answered that there seems no clear advantage to keeping elective resection patients nil by mouth — early feeding may benefit, pending an adequately powered trial.^[36] Two decades of trials filled in the safety case. After upper gastrointestinal surgery, early oral feeding shortens stay with no excess leak, pneumonia, tube reinsertion, reoperation, readmission, or mortality — and pooled with non-randomised data, early feeding halves pneumonia odds (OR 0.6).^[37] After pancreatoduodenectomy, early oral feeding does not worsen fistula or delayed emptying and shortens stay by 3.40 days against EN/PN controls.^[38] After resectional surgery generally, early nutrition significantly reduces total complications without harming mortality, dehiscence, bowel recovery, or stay — with the direction of every outcome favouring early feeding.^[39] After elective colorectal surgery specifically, early oral feeding cut stay by 1.58 days and total complications (RR 0.70) with no difference in dehiscence, pneumonia, wound infection, tube reinsertion, vomiting, or mortality.^[40]

Three caveats keep the viva honest. Early enteral nutrition within 24 hours associates with reduced mortality by an unclear mechanism — a signal to quote, not a mechanism to invent.^[41] Cochrane colorectal flags the one significant mortality benefit as not necessarily feeding-attributable, since deaths came from leak, reoperation, and myocardial infarction — a significant result that still does not prove causation.^[42] And certainty stays low: bowel-surgery tolerance data call for confirmatory studies, gastrectomy safety rests on very-low-certainty evidence, and after Whipple the jejunostomy-versus-oral question is explicitly very uncertain with a network meta-analysis still needed.^[43][44][45] The operational rules are simple: start parenteral nutrition when patients cannot cover half their energy needs within 3-4 days, and after major upper-gastrointestinal operations expect the route trade — nasoenteric tubes dislodge more, jejunostomies leak more, with nasoenteric the likelier effective early route.^[46][47]

EN vs PN — Route Discipline and the VA Rule

The VA trial is the gatekeeper for preoperative parenteral nutrition: 395 malnourished laparotomy and thoracotomy patients randomised to TPN for 7-15 days before surgery plus 3 days after, or to no perioperative TPN, with 90-day follow-up.^[48] Overall the groups tied on major complications and 90-day mortality — but infections doubled with TPN (14.1 versus 6.4%, RR 2.20) confined to borderline and mildly malnourished patients who gained nothing, while the severely malnourished on TPN suffered far fewer non-infectious complications (5 versus 43%, RR 0.12) with no extra infections.^[48] The rule follows the data: limit preoperative TPN to the severely malnourished unless another specific indication exists.^[48] The companion analysis closes the loophole — benefit only in severe malnutrition, septic risk in the rest, so TPN has no place in the non-severely malnourished without a specific indication.^[49]

Elsewhere, route discipline favours the gut. After pancreatoduodenectomy, enteral nutrition shortens stay by 1.63 days against parenteral with no difference in fistula, bleeding, or infections — choose EN for recovery speed, not leak prevention.^[50] Peripheral parenteral nutrition earns its place as the bridge: effective short-term delivery that facilitates early feeding with few patients needing escalation to central TPN, low cannula-complication rates, and favourable costs.^[51] Dose parenteral feeding honestly: 25 kcal per kg ideal body weight approximates daily needs, approaching 30 under severe stress — with a full daily range of vitamins and trace elements whenever total or near-total PN runs.^[52]

Immunonutrition — Combination, Timing, Boundaries

Braga's pharmaconutrition verdict anchors the section: enteral diets supplemented with specific nutrients significantly improved short-term outcomes in cancer patients undergoing elective gastrointestinal surgery.^[53] The gastrointestinal meta-analysis concurs — perioperative immunonutrition is effective and safe, cutting postoperative infection and stay through improved immunity.^[54] Timing matters: the Bayesian network analysis finds the perioperative regimen the optimum for infections and stay against pre- or post-operative alone.^[55] The effect has a ceiling: immunonutrition reduces postoperative infections and shortens hospitalisation but does not reduce all-cause mortality.^[56]

Write the prescription with numbers. In malnourished preoperative patients, arginine plus nucleotides plus omega-3 at 25-30 kcal/kg/d via the gut across the perioperative 5-7 days shows the best clinical efficacy.^[56] The 2024 Annals meta-analysis (48 studies, 4825 patients) reports high-certainty cuts in total complications (RR 0.78) and infectious complications (RR 0.71) against standard nutrition.^[57] In upper gastrointestinal cancer specifically, the infectious-complication reduction runs about 30%.^[58] The umbrella review adds 1.92 fewer hospital days.^[59] And the 2026 gastrointestinal meta-analysis is the most granular: arginine-nucleotide-omega-3 perioperatively cut anastomotic leak (OR 0.62), respiratory, urinary, wound, and sepsis infections, and shortened stay by 2.47 days — while omega-3 alone changed nothing, so prescribe the combination, never the single nutrient.^[60]

Two boundaries complete the picture. After oesophagectomy specifically, evidence is currently insufficient to recommend routine immunonutrition for mortality, stay, or morbidity — withhold routine use there while using it in broader gastrointestinal-cancer surgery.^[61] And the value case exists: in elective gastrointestinal-cancer surgery, immunonutrition proved effective and cost-saving, with savings holding above 3.5% baseline complication rates.^[62]

ESPEN Architecture — the 44-Recommendation Spine

ESPEN 2017 organises perioperative care around eight metabolic-nutritional principles: integrate nutrition into overall management, avoid long preoperative fasts, re-establish oral feeding as early as possible, start therapy early as soon as nutritional risk appears, control blood glucose, curb catabolism and gut dysfunction, minimise paralysis time, and mobilise early for protein synthesis and muscle function — across 37 recommendations centred on ERAS and the special needs of cancer and severely complicated patients.^[1] Early oral feeding is the preferred mode, and avoiding nutritional therapy risks underfeeding after major surgery — with early enteral feeding especially relevant for any patient at nutritional risk and particularly after upper gastrointestinal surgery.^[1] The 2021 practical guideline restates the spine, including starting therapy immediately once risk appears.^[63] The 2025 update grows to 44 recommendations for elective and non-elective surgery, adding frailty assessment, sarcopenia diagnosis, and prehabilitation — and restates the principles in decision-making flowcharts.^[2] The expert-group companion adds the conditioning view: assess the patient, restore the energy deficit, avoid weight loss, preserve the microbiome, and improve functional performance — with pharmaconutrition plus pre-, pro-, and syn-biotics carrying stronger evidence in gastrointestinal-cancer surgery.^[64]

Refeeding — the Starvation-to-Fed Switch

Refeeding syndrome is the metabolic response to switching from starvation to fed in the first phase of nutritional therapy: glucose rises, phosphate, potassium, and magnesium fall, thiamine depletes, salt and fluid retain — with organ dysfunction and arrhythmia as the price, hypophosphataemia heading the electrolyte list.^[66] ASPEN stratifies by the fall within 5 days of calorie reintroduction: 10-20% in any of phosphate, potassium, or magnesium is mild, 20-30% moderate, and over 30% — or any organ dysfunction from these falls or from thiamine deficiency — severe.^[65] The 2025 Australasian consensus tightens the diagnosis: only after adequate intake (at least 50% of estimated needs) with emergent imbalance plus symptoms — then thiamine plus multivitamin and regular electrolyte monitoring for every at-risk patient, goal rates within 24-72 hours for all routes with no mandated slow enteral start, and replacement of low electrolytes per local protocol.^[68]

Prevention is the whole game because awareness stays poor and high-quality evidence thin: risk-assess and stratify every patient before nutritional therapy, adapt energy and fluid support through the high-risk replenishment phase, and re-evaluate continuously during feeding.^[66][67] Detection is genuinely difficult — prospective testing caught two-thirds of cases even with decision support — so the threshold for monitoring stays low.^[69]

Fistula & Intestinal Failure — Nutrition as Therapy

In enterocutaneous fistula, malnutrition is common and provision essential: enteral where possible, with supplemental parenteral nutrition often required for high-output small-bowel fistulas — the immunonutrition role unknown, and surgical repair delayed at least 3 months without spontaneous closure.^[70] Intestinal failure itself is defined functionally: gut function below the minimum for macronutrient and/or water-electrolyte absorption such that intravenous supplementation is required to maintain health or growth.^[71] The Type 2 sequence is non-negotiable: resolve sepsis before nutritional repletion can succeed, optimise status including short-bowel complications, and only then reconstruct — feeding through uncontrolled sepsis fails, and structured care should prevent slide into chronic Type 3 failure.^[72] Current fistula care gathers the sequence into one multidisciplinary prescription: source control, nutritional optimisation centred on enteral nutrition, wound care, and prehabilitation.^[74] When parenteral nutrition runs long, plan it: outpatient monitoring, target weight, and a defined PN end point belong in the discharge prescription alongside fluid-electrolyte stability, glycaemic control, and output containment.^[75] And state the evidence limit honestly: fistula nutrition guidelines are often vague, built on limited dated studies and institutional experience — the ASPEN-FELANPE seven questions (status markers, route, protein-energy dose, fistuloclysis, immune formulas, somatostatin analogues, home PN) are answered under GRADE with consensus humility.^[73]

Exam Synthesis & Fence Map — what this topic owns

This topic owns the perioperative ward-level nutrition story and fences everything else: screening with NRS-2002 and MUST plus GLIM diagnosis and grading; ERAS nutrition with carbohydrate loading and fasting discipline; prehabilitation with its certainty gradient; preoperative therapy targeted to the depleted; early oral and enteral feeding with route discipline; the VA-limited role of preoperative TPN; elective gastrointestinal-cancer immunonutrition; ward-level refeeding vigilance; sarcopenia and frailty as surgical risk; malnutrition-outcome links with ESPEN energy targets; and fistula and intestinal-failure nutrition principles.^{[1][6][22][28][36][48][53][65][70]} Intensive-care feeding — trophic versus full enteral volumes, day-8 versus early parenteral timing, shock-gut management, protein dosing with kidney-injury harm, pharmaconutrition harm in multiorgan failure, glycaemic targets, and tube prokinetics — belongs to icu-nutrition-surgical; crystalloids and overload to fluids-electrolytes; gaps and lactate to acid-base-balance; closure, sutures, negative pressure, and leak biology to wound-healing; every antimicrobial decision to surgical-infection-antimicrobials; fistula execution, short-gut management, and stomas to their owner topics; and blood products to massive-transfusion.^[46][64] The one-paragraph nutrition story for the viva: screen all admissions because a third of gastrointestinal-surgery candidates are GLIM-malnourished; grade with one phenotypic plus one etiologic criterion; prehabilitate the frail for a day off stay and nearly half the severe complications; load carbohydrates for insulin sensitivity without promising comfort; fast solids but free clears to 2 hours; feed early because the anastomosis is not a reason to starve; give TPN preoperatively only to the severely malnourished; add arginine-nucleotide-omega-3 around gastrointestinal-cancer surgery but not routinely at the oesophagus; and refeed under phosphate watch with thiamine aboard.^{[8][6][30][22][18][40][48][60][61][68]}

Exam Pearls — the one-liners that score

• Screen with MUST (86% sensitive, 89% specific) or NRS-2002 (88%/92%) — then assess, because screens miss GLIM malnutrition (50-82% sensitivity) and MUST alone cannot trigger optimisation.^[3][4][7]
• GLIM: one phenotypic plus one etiologic criterion; Stage 1 moderate, Stage 2 severe; 32.3% of gastrointestinal-surgery candidates malnourished, severe form predominant.^[6][8]
• Sarcopenia adds 1.46 days and nearly triples 30-day mortality after colorectal-cancer surgery (RR 2.74, low certainty); frailty beats traditional risk scores — assess both plus delirium risk.^[16][14][17]
• Fast solids, free clears to 2 hours, resume eating as soon as able — prolonged fasting harms glucose control, bowel recovery, and muscle.^[18]
• Carbohydrate loading (≈12% maltodextrin; 50 g night + 25 g at 2 h) halves insulin resistance without moving complications or stay — and does nothing for discomfort or day surgery.^{[20][21][22][24]}
• Prehabilitation: nutrition alone cuts complications (OR 0.62, very-low certainty); multimodal cuts frail-elder severe complications 44% — definition first, better trials next.^[28][30][26]
• Target supplements: Cochrane GI uncertain overall, but ONS probably cuts infections in the weight-losing (RR 0.58); support in the malnourished cuts infections (RR 0.58) and stay 2.64 days.^[32][33]
• Feed early: colorectal stay down 1.58 days with complications RR 0.70 and no leak excess; Whipple jejunostomy-versus-oral uncertain; PN when half of needs unmet at 3-4 days.^[40][45][46]
• VA rule: preoperative TPN only for the severely malnourished (5% vs 43% non-infectious complications, RR 0.12) — in the rest it doubles infections (RR 2.20) with no benefit.^[48]
• Immunonutrition: arginine-nucleotide-omega-3 perioperatively cuts leak (OR 0.62) and stay 2.47 days; omega-3 alone does nothing; oesophageal routine use unsupported.^[60][61]
• ESPEN: 37 recommendations in 2017, 44 in 2025 (frailty, sarcopenia, prehab added); 25 kcal/kg, 30 stressed; early oral first, therapy at first risk.^[1][2][52]
• Refeeding: 10-20% fall mild, 20-30% moderate, over 30% or organ injury severe within 5 days — thiamine plus multivitamin for all at risk, goals in 24-72 hours, phosphate watched throughout.^[65][68]
• Fistula: enteral first, PN for high-output small bowel, repair at 3 months; intestinal failure means IV support required for health — sepsis resolved before repletion.^[70][71][72]
• EFFORT generalises with a fence: individualised support improved survival in at-risk medical inpatients — screen every admission, assess, then target.^[76]

BMJ component NMA (186 RCTs, 15684 participants): isolated nutritional prehabilitation cuts complications (OR 0.62) and stay (~1 day) at very-low certainty, and nutrition plus exercise is among the best combinations — quote both numbers with their certainty labels.^[24]

References76ShowHide

1. [1]Weimann A, et al. ESPEN guideline: Clinical nutrition in surgery. Clin Nutr, 2017.PMID 28385477
2. [2]Weimann A, et al. ESPEN guideline on clinical nutrition in surgery - Update 2025. Clin Nutr, 2025.PMID 40957230
3. [3]Cheung HHT, et al. Diagnostic test accuracy of preoperative nutritional screening tools in adults for malnutrition: a systematic review and network meta-analysis. Int J Surg, 2024.PMID 37830947
4. [4]Bolayir B, et al. Validation of Nutritional Risk Screening-2002 in a Hospitalized Adult Population. Nutr Clin Pract, 2019.PMID 29603374
5. [5]Gupta A, et al. Preoperative malnutrition in patients with colorectal cancer. Can J Surg, 2021.PMID 34824150
6. [6]Cederholm T, et al. GLIM criteria for the diagnosis of malnutrition - A consensus report from the global clinical nutrition community. Clin Nutr, 2019.PMID 30181091
7. [7]Fiorindi C, et al. GLIM Criteria for Malnutrition in Surgical IBD Patients: A Pilot Study. Nutrients, 2020.PMID 32722435
8. [8]Santos MLDD, et al. PREVALENCE OF MALNUTRITION, ACCORDING TO THE GLIM CRITERIA, IN PATIENTS WHO ARE THE CANDIDATES FOR GASTROINTESTINAL TRACT SURGERY. Arq Bras Cir Dig, 2022.PMID 35766608
9. [9]Barazzoni R, et al. Guidance for assessment of the muscle mass phenotypic criterion for the Global Leadership Initiative on Malnutrition (GLIM) diagnosis of malnutrition. Clin Nutr, 2022.PMID 35450768
10. [10]Alves LF, et al. GLIM criteria to identify malnutrition in patients in hospital settings: A systematic review. JPEN J Parenter Enteral Nutr, 2023.PMID 37314206
11. [11]Cederholm T, et al. The GLIM consensus approach to diagnosis of malnutrition: A 5-year update. Clin Nutr, 2025.PMID 40222089
12. [12]Correia MITD, et al. Utilization and validation of the Global Leadership Initiative on Malnutrition (GLIM): A scoping review. Clin Nutr, 2022.PMID 35151125
13. [13]de van der Schueren MAE, et al. Global Leadership Initiative on Malnutrition (GLIM): Guidance on validation of the operational criteria for the diagnosis of protein-energy malnutrition in adults. Clin Nutr, 2020.PMID 32563597
14. [14]Keevil VL, et al. Ageing well: a review of sarcopenia and frailty. Proc Nutr Soc, 2015.PMID 26004622
15. [15]Shen Y, et al. The impact of frailty and sarcopenia on postoperative outcomes in older patients undergoing gastrectomy surgery: a systematic review and meta-analysis. BMC Geriatr, 2017.PMID 28826406
16. [16]Keshavjee S, et al. The Impact of Sarcopenia on Postoperative Outcomes in Colorectal Cancer Surgery: An Updated Systematic Review and Meta-Analysis. Am Surg, 2025.PMID 40127466
17. [17]Moellmann HL, et al. Risk of sarcopenia, frailty and malnutrition as predictors of postoperative delirium in surgery. BMC Geriatr, 2024.PMID 39604907
18. [18]Rüggeberg A, et al. Peri-operative fasting in adults: an international, multidisciplinary consensus statement. Anaesthesia, 2026.PMID 41657234
19. [19]Anderson M, et al. Adopting preoperative fasting guidelines. AORN J, 2009.PMID 19580897
20. [20]Pogatschnik C, et al. Review of Preoperative Carbohydrate Loading. Nutr Clin Pract, 2015.PMID 26197803
21. [21]Kumar M, et al. Preoperative carbohydrate loading reduces perioperative insulin resistance and hastens functional recovery of remnant liver after living donor hepatectomy: An open-label randomized controlled trial. Hepatol Int, 2025.PMID 40389625
22. [22]Tong E, et al. Effects of preoperative carbohydrate loading on recovery after elective surgery: A systematic review and Bayesian network meta-analysis of randomized controlled trials. Front Nutr, 2022.PMID 36505254
23. [23]Ackerman RS, et al. How Sweet Is This? A Review and Evaluation of Preoperative Carbohydrate Loading in the Enhanced Recovery After Surgery Model. Nutr Clin Pract, 2020.PMID 31637778
24. [24]Kukliński J, et al. Perioperative carbohydrate loading in patients undergoing one-day surgery. A systematic review of randomized controlled trials. Wideochir Inne Tech Maloinwazyjne, 2022.PMID 36187066
25. [25]Pillinger NL, et al. Nutritional prehabilitation: physiological basis and clinical evidence. Anaesth Intensive Care, 2018.PMID 30189818
26. [26]Fleurent-Grégoire C, et al. Towards a common definition of surgical prehabilitation: a scoping review of randomised trials. Br J Anaesth, 2024.PMID 38677949
27. [27]McIsaac DI, et al. Prehabilitation in adult patients undergoing surgery: an umbrella review of systematic reviews. Br J Anaesth, 2022.PMID 34922735
28. [28]McIsaac DI, et al. Relative efficacy of prehabilitation interventions and their components: systematic review with network and component network meta-analyses of randomised controlled trials. BMJ, 2025.PMID 39843215
29. [29]Shen Y, et al. Effect of nutrition-based prehabilitation on the postoperative outcomes of patients with esophagogastric cancer undergoing surgery: A systematic review and meta-analysis. Cancer Med, 2024.PMID 39001679
30. [30]Skořepa P, et al. The impact of prehabilitation on outcomes in frail and high-risk patients undergoing major abdominal surgery: A systematic review and meta-analysis. Clin Nutr, 2024.PMID 38306891
31. [31]Gillis C, et al. Prehabilitation, enhanced recovery after surgery, or both? A narrative review. Br J Anaesth, 2022.PMID 35012741
32. [32]Sowerbutts AM, et al. Preoperative nutrition therapy in people undergoing gastrointestinal surgery. Cochrane Database Syst Rev, 2024.PMID 38588454
33. [33]Zhong JX, et al. Effect of nutritional support on clinical outcomes in perioperative malnourished patients: a meta-analysis. Asia Pac J Clin Nutr, 2015.PMID 26420176
34. [34]Delsoglio M, et al. High-protein oral nutritional supplement use in patients with cancer reduces complications and length of hospital stay: a systematic review and meta-analysis. Front Nutr, 2025.PMID 41001134
35. [35]Meng Q, et al. Post-discharge oral nutritional supplements with dietary advice in patients at nutritional risk after surgery for gastric cancer: A randomized clinical trial. Clin Nutr, 2021.PMID 32563598
36. [36]Lewis SJ, et al. Early enteral feeding versus nil by mouth after gastrointestinal surgery: systematic review and meta-analysis of controlled trials. BMJ, 2001.PMID 11588077
37. [37]Willcutts KF, et al. Early Oral Feeding as Compared With Traditional Timing of Oral Feeding After Upper Gastrointestinal Surgery: A Systematic Review and Meta-analysis. Ann Surg, 2016.PMID 26779983
38. [38]Halle-Smith JM, et al. Early oral feeding after pancreatoduodenectomy: a systematic review and meta-analysis. HPB (Oxford), 2022.PMID 35606323
39. [39]Osland E, et al. Early versus traditional postoperative feeding in patients undergoing resectional gastrointestinal surgery: a meta-analysis. JPEN J Parenter Enteral Nutr, 2011.PMID 21628607
40. [40]Zhuang CL, et al. Early versus traditional postoperative oral feeding in patients undergoing elective colorectal surgery: a meta-analysis of randomized clinical trials. Dig Surg, 2013.PMID 23838894
41. [41]Lewis SJ, et al. Early enteral nutrition within 24 h of intestinal surgery versus later commencement of feeding: a systematic review and meta-analysis. J Gastrointest Surg, 2009.PMID 18629592
42. [42]Andersen HK, et al. Early enteral nutrition within 24h of colorectal surgery versus later commencement of feeding for postoperative complications. Cochrane Database Syst Rev, 2006.PMID 17054196
43. [43]Mvoula L, et al. Tolerance to and postoperative outcomes with early oral feeding following elective bowel surgery: a systematic review with meta-analysis. Ann Coloproctol, 2024.PMID 39086353
44. [44]Mohajeri L, et al. Early oral feeding after laparoscopic total gastrectomy in gastric cancer patients: a meta-analysis of randomized controlled trials and cohort studies. BMC Gastroenterol, 2025.PMID 41068719
45. [45]Robertson RH, et al. Postoperative nutritional support after pancreaticoduodenectomy in adults. Cochrane Database Syst Rev, 2025.PMID 40084692
46. [46]Strobel RM, et al. The updated recommendations for medical nutrition in the perioperative period: a focus on early oral intake. Curr Opin Clin Nutr Metab Care, 2026.PMID 42348611
47. [47]Wang L, et al. Nasoenteric tube versus jejunostomy for enteral nutrition feeding following major upper gastrointestinal operations: a meta-analysis. Asia Pac J Clin Nutr, 2017.PMID 28049257
48. [48]Veterans Affairs Total Parenteral Nutrition Cooperative Study Group, et al. Perioperative total parenteral nutrition in surgical patients. N Engl J Med, 1991.PMID 1906987
49. [49]Williford WO, et al. Comparison of eligible randomized patients with two groups of ineligible patients: can the results of the VA Total Parenteral Nutrition clinical trial be generalized? J Clin Epidemiol, 1993.PMID 8263575
50. [50]Adiamah A, et al. Enteral versus parenteral nutrition following pancreaticoduodenectomy: a systematic review and meta-analysis. HPB (Oxford), 2019.PMID 30773452
51. [51]Inayat-Hussain A, et al. Peripheral parenteral nutrition: An evaluation of its use, safety and cost implications in a tertiary hospital setting. Clin Nutr ESPEN, 2023.PMID 37344076
52. [52]Braga M, et al. ESPEN Guidelines on Parenteral Nutrition: surgery. Clin Nutr, 2009.PMID 19464088
53. [53]Braga M, et al. Clinical evidence for pharmaconutrition in major elective surgery. JPEN J Parenter Enteral Nutr, 2013.PMID 24009251
54. [54]Zheng Y, et al. Application of perioperative immunonutrition for gastrointestinal surgery: a meta-analysis of randomized controlled trials. Asia Pac J Clin Nutr, 2007.PMID 17392114
55. [55]Song GM, et al. Immunonutrition Support for Patients Undergoing Surgery for Gastrointestinal Malignancy: Preoperative, Postoperative, or Perioperative? A Bayesian Network Meta-Analysis of Randomized Controlled Trials. Medicine (Baltimore), 2015.PMID 26200648
56. [56]Yu K, et al. Immunonutrition vs Standard Nutrition for Cancer Patients: A Systematic Review and Meta-Analysis (Part 1). JPEN J Parenter Enteral Nutr, 2020.PMID 31709584
57. [57]Matsui R, et al. Impact of Perioperative Immunonutrition on Postoperative Outcomes for Patients Undergoing Head and Neck or Gastrointestinal Cancer Surgeries: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Ann Surg, 2024.PMID 37882375
58. [58]Matsui R, et al. Impact of Perioperative Immunonutrition on Postoperative Outcomes in Patients with Upper Gastrointestinal Cancer: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients, 2024.PMID 38474706
59. [59]Goyal A, et al. Perioperative Immunonutrition in Gastrointestinal Oncology: A Comprehensive Umbrella Review and Meta-Analysis on Behalf of TROGSS-The Robotic Global Surgical Society. Nutrients, 2025.PMID 40732929
60. [60]Budai BC, et al. Immunonutrition Decreases Postoperative Complications in Gastrointestinal Cancer-A Systematic Review and Meta-analysis of Randomized Controlled Trials. Adv Nutr, 2026.PMID 42331289
61. [61]Mudge L, et al. Immunonutrition in patients undergoing esophageal cancer resection. Dis Esophagus, 2011.PMID 20946133
62. [62]Mauskopf JA, et al. Immunonutrition for patients undergoing elective surgery for gastrointestinal cancer: impact on hospital costs. World J Surg Oncol, 2012.PMID 22770421
63. [63]Weimann A, et al. ESPEN practical guideline: Clinical nutrition in surgery. Clin Nutr, 2021.PMID 34242915
64. [64]Lobo DN, et al. Perioperative nutrition: Recommendations from the ESPEN expert group. Clin Nutr, 2020.PMID 32362485
65. [65]da Silva JSV, et al. ASPEN Consensus Recommendations for Refeeding Syndrome. Nutr Clin Pract, 2020.PMID 32115791
66. [66]Reber E, et al. Management of Refeeding Syndrome in Medical Inpatients. J Clin Med, 2019.PMID 31847205
67. [67]Friedli N, et al. Refeeding syndrome: update and clinical advice for prevention, diagnosis and treatment. Curr Opin Gastroenterol, 2020.PMID 31895231
68. [68]Matthews-Rensch K, et al. The Australasian Society of Parenteral and Enteral Nutrition: Consensus statements on refeeding syndrome. Nutr Diet, 2025.PMID 40090863
69. [69]Heuft L, et al. Refeeding Syndrome. Dtsch Arztebl Int, 2023.PMID 36482748
70. [70]Lloyd DA, et al. Nutrition and management of enterocutaneous fistula. Br J Surg, 2006.PMID 16804873
71. [71]Pironi L, et al. ESPEN endorsed recommendations. Definition and classification of intestinal failure in adults. Clin Nutr, 2015.PMID 25311444
72. [72]Lal S, et al. Review article: intestinal failure. Aliment Pharmacol Ther, 2006.PMID 16803600
73. [73]Kumpf VJ, et al. ASPEN-FELANPE Clinical Guidelines. JPEN J Parenter Enteral Nutr, 2017.PMID 27913762
74. [74]Vanzant E, et al. Current fistula management. Curr Opin Crit Care, 2024.PMID 38441138
75. [75]Kumpf VJ, et al. Use of parenteral nutrition in the management of enterocutaneous fistula. Nutr Clin Pract, 2025.PMID 39601380
76. [76]Schuetz P, et al. Individualised nutritional support in medical inpatients at nutritional risk: a randomised clinical trial. Lancet, 2019.PMID 31030981