Gastrointestinal & Hepatic · Topic 23 of 26

Malnutrition in the Hospitalized Adult

Nutrition · malnutrition assessment

Malnutrition in the Hospitalized Adult

Diagnose malnutrition from weight loss, intake, muscle and fat — not albumin — then feed critically ill patients 1.2–2.0 g/kg/day of protein.

Key numbers

ASPEN/AND: 2 of 6 characteristics≥ 2 of 6

ICU protein 1.2–2.0 g/kg/day1.2–2.0 g/kg/day

ICU energy 12–25 kcal/kg/day early12–25 kcal/kg/day

High ICU nutrition risk: NRS-2002 ≥ 5NRS-2002 ≥ 5 / NUTRIC ≥ 5

01 · Defined byGLIM: one phenotypic plus one etiologic

GLIM diagnoses malnutrition with at least 1 phenotypic criterion (weight loss, low BMI, reduced muscle mass) plus at least 1 etiologic criterion (reduced intake or assimilation, or inflammation/disease burden), after a positive screen.

02 · The ruleAlbumin is not a nutrition marker

Do not use serum albumin or prealbumin to diagnose malnutrition or judge nutrition therapy: they fall with inflammation and capillary leak and track illness severity and outcome risk, not protein-energy status.

03 · The numberICU protein 1.2–2.0 g/kg/day

Critically ill adults need 1.2–2.0 g/kg/day of protein (actual body weight), possibly more after burns or multitrauma; protein delivery is tracked separately from calories.

What it is

Core idea

Classify malnutrition by its cause and inflammationBoth frameworks label malnutrition by context — acute illness or injury, chronic disease, or starvation from social or environmental causes — because the degree of inflammation guides treatment and expected response.

Causes & risk factors

Why it happens

Malnourished patients are at refeeding riskMalnutrition, low BMI, recent weight loss and days of negligible intake predict refeeding syndrome: check potassium, phosphate and magnesium and give thiamine before feeding (see the refeeding syndrome sheet).

Presentation

What you'll see

Examine for muscle wasting, fat loss, edemaThe nutrition-focused exam looks for loss of muscle mass and subcutaneous fat, fluid accumulation that can hide weight loss, and reduced grip strength; muscle mass can be quantified by DXA, bioimpedance, CT or MRI.

Diagnosis & monitoring

Work-up

ASPEN/AND: 2 of 6 characteristics must knowASPEN/AND diagnoses malnutrition when 2 or more of 6 are present: insufficient energy intake, weight loss, loss of subcutaneous fat, loss of muscle mass, fluid accumulation masking weight loss, reduced grip strength.

ICU energy 12–25 kcal/kg/day early must knowASPEN (2022) targets 12–25 kcal/kg/day over the first 7–10 days of critical illness; indirect calorimetry is preferred when available because predictive equations are inaccurate.

GLIM thresholds: weight, BMI and intakeGLIM cut-offs: weight loss over 5% in 6 months or over 10% beyond 6 months; BMI under 20 (age under 70) or under 22 (70 or older); intake ≤ 50% of needs over 1 week.

GLIM severe: over 10% loss in 6 monthsGLIM stage 2 (severe) malnutrition: weight loss over 10% within 6 months or over 20% beyond 6 months, BMI under 18.5 (under 70 years) or under 20 (70 or older), or a severe muscle-mass deficit.

Severe malnutrition in acute illness: intake ≤ 50%ASPEN/AND severe malnutrition in acute illness: intake ≤ 50% of estimated needs for 5 or more days, or weight loss over 2% in 1 week, 5% in 1 month or 7.5% in 3 months.

High ICU nutrition risk: NRS-2002 ≥ 5High nutrition risk in the ICU = NRS-2002 ≥ 5 or NUTRIC ≥ 5 (without IL-6); these patients benefit most from early enteral nutrition advanced to over 80% of goal within 48–72 hours.

Obesity: high-protein, hypocaloric feedingFeed critically ill obese patients high-protein, hypocaloric: 11–14 kcal/kg actual weight (BMI 30–50) or 22–25 kcal/kg ideal weight (BMI over 50); protein 2.0 g/kg ideal weight (BMI 30–40) to 2.5 g/kg (BMI ≥ 40).

Management

Orders

Screen first, then assess and diagnoseMalnutrition diagnosis is two-step: screen with a validated tool (NRS-2002 in hospital, MUST, MNA in older adults, NUTRIC in the ICU), then assess and grade positives with GLIM or ASPEN/AND criteria.

Count propofol and dextrose caloriesWhen setting the energy goal, count non-nutrition calories from dextrose-containing fluids and lipid-based drugs such as propofol to avoid overfeeding.

The rules

Know these

Low-risk ICU patients can wait a weekWell-nourished, low-risk ICU patients (NRS-2002 ≤ 3, low NUTRIC) who cannot eat do not need specialized nutrition therapy during the first ICU week; reassess risk daily.

ASPEN/AND or GLIM?

Commonly confused

Rule to diagnose	2 or more of 6 characteristics
Weight loss	Time-based by context (e.g., > 2% in 1 week, > 5% in 1 month in acute illness = severe)
Low BMI	Not a criterion
Function	Reduced grip strength is a characteristic
Severity	Non-severe (moderate) or severe

More detail

Reference

Show 4 reference facts

In EFFORT Protein, ≥ 2.2 versus ≤ 1.2 g/kg/day of protein gave no benefit and was linked to longer ICU dependency and higher mortality in the sickest patients and those with AKI.

Patients on continuous renal replacement therapy need more protein (1.5–2.5 g/kg/day); AKI patients get standard ICU protein (1.2–2 g/kg/day) and a standard formula — do not restrict protein to delay dialysis.

Chronically critically ill patients (ICU stay over 21 days with persistent organ dysfunction) should receive aggressive high-protein enteral nutrition plus a resistance exercise program when feasible.

European (ESPEN) guidance is more cautious: start hypocaloric, advance to target over 3–7 days, and deliver 1.3 g/kg/day protein progressively.

Pearl

Albumin tells you how inflamed the patient is, not how fed: the scale, the diet history and the temporal muscles tell you about nutrition.

Sources · Cederholm T et al. GLIM criteria for the diagnosis of malnutrition — a consensus report from the global clinical nutrition community. J Cachexia Sarcopenia Muscle 2019;10:207–217 (also JPEN 2019;43:32–40) · White JV et al. Consensus statement: Academy of Nutrition and Dietetics and ASPEN — characteristics recommended for the identification and documentation of adult malnutrition. JPEN 2012;36:275–283 · Evolution of the diagnosis of malnutrition in adults: a primer for clinicians. Front Nutr 2024 (Table 2 compares AND/ASPEN, ESPEN and GLIM criteria) · McClave SA, Taylor BE et al. Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult Critically Ill Patient: SCCM and ASPEN. Crit Care Med 2016;44:390–438 / JPEN 2016;40:159–211 · Compher C et al. Guidelines for the provision of nutrition support therapy in the adult critically ill patient: ASPEN. JPEN 2022;46:12–41 · de Man AME, Gunst J, Reintam Blaser A. Nutrition in the intensive care unit: from the acute phase to beyond. Intensive Care Med 2024 (Table 2: ASPEN 2022 vs ESPEN targets; EFFORT Protein) · Evans DC et al. The use of visceral proteins as nutrition markers: an ASPEN position paper. Nutr Clin Pract 2021;36:22–28 · Merck Manual Professional — Parenteral Nutrition (PN): table of basic adult daily requirements (ASPEN dosing) · Understanding Refeeding Syndrome in Critically Ill Patients: A Narrative Review. Nutrients 2025;17:1866 · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).