Malnutrition in Older Adults — Causes, Approach to Diagnosis, Assessment and Management

Definition. As per WHO, malnutrition means deficiencies, excesses or imbalances in energy and nutrient intake. In geriatric practice, “malnutrition” and undernutrition (protein-energy malnutrition) are used interchangeably.

It is a geriatric syndrome, not a single disease. Like falls or delirium, it is multifactorial with poor outcomes and needs a multi-domain approach. Three overlapping presentations exist: starvation (pure intake deficit, responds to refeeding), cachexia (inflammation-driven, does not respond to refeeding alone), and sarcopenia (loss of muscle mass and strength, may occur with normal weight).

Epidemiology. Using MNA, overall prevalence is 22.8% — rehabilitation 50.5%, hospital 38.7%, community 5.8%. European meta-analysis: long-term care 28.7%, rehabilitation 29.4%, hospital 22%, nursing home 17.5%, community 6%. People aged >70 consume about one-third fewer calories than the young, and 16–18% of community elders eat <1000 kcal/day.

Physiological — the anorexia of ageing. (a) Loss of homeostatic regulation — elders fail to regain weight after underfeeding; (b) ageing gut — impaired fundic accommodation (raised nitric oxide), delayed gastric emptying, early satiation; (c) declining senses — over 50% aged 65–80 and >75% aged over 80 have measurable olfactory decline, and 46% of those with olfactory dysfunction have a change in appetite or weight; reduced sensory-specific satiety narrows dietary variety; (d) hormonal — raised CCK (levels + sensitivity), leptin, insulin and PYY.

Medical and psychiatric causes. Depression (2–10% of community elders, far more in institutions; the commonest reversible cause), dementia (≈2-fold risk of anorexia; up to 50% of institutionalised dementia patients have PEM), COPD, CHF (anorexia in >40% of end-stage), CKD/dialysis (30–40%), cancer, chronic infection, hyperthyroidism, malabsorption, constipation and faecal impaction, H. pylori infection.

Oral, swallowing and GI causes. Edentulism and ill-fitting dentures (denture wearers have poorer protein intake), xerostomia, oral candidiasis, dysphagia (cranial nerves V, VII, IX, X, XI; worsened by stroke and dementia), atrophic gastritis with hypochlorhydria impairing B12 and iron absorption.

Functional and social causes. Immobility (stroke), tremor (Parkinson’s), impaired vision all limit shopping, cooking and self-feeding. Poverty and food insecurity, living alone (elders eat up to 50% more when eating in company), social isolation, institutionalisation, failure of facilities to cater to ethnic food preferences, and unnecessary restrictive therapeutic diets.

Iatrogenic causes — polypharmacy. More than 250 prescribed drugs alter taste. Digoxin and chemotherapy cause nausea and anorexia; aluminium/magnesium hydroxide antacids deplete phosphate and potassium causing weakness and anorexia; penicillamine causes zinc depletion and loss of taste; high-fibre diets cause excess satiety.

Bedside mnemonic — “MEALS ON WHEELS” (recommended by Pathy’s to find treatable causes): Medications · Emotional (depression) · Anorexia tardive/alcoholism · Late-life paranoia · Swallowing disorders · Oral factors · No money · Wandering/dementia · Hyper/hypothyroidism, hyperparathyroidism, hypoadrenalism · Enteric (malabsorption) · Eating problems (unable to self-feed) · Low-salt/low-cholesterol diets · Social isolation, Stones.

Consequences (why it matters). ↓Muscle mass and strength → falls; ↓bone mass → fractures; immune dysfunction → infection and pneumonia; anaemia; poor wound healing and pressure ulcers (prevalence up to 30% in long-term care, 19% in home care); cognitive impairment; delayed surgical recovery; longer hospital stay; more admissions; increased mortality. PEM is a strong independent predictor of mortality in community, nursing home and hospital settings, and the risk is amplified by renal failure, cardiac failure and stroke.

Step 1 — SCREEN every older person. Use MNA-SF: 12–14 normal, 8–11 at risk, 0–7 malnourished; body mass entered as BMI or calf circumference (<31 cm). MNA is 96% sensitive and 60% specific for weight loss and is a powerful independent prognostic factor. Alternatives: MUST, NRS-2002, SNAQ, SGA. In nursing homes, weigh monthly — persistent weight loss must trigger a search for treatable causes.

Step 2 — DIAGNOSE using the GLIM criteria (need one phenotypic + one etiologic criterion):

Step 3 — GRADE the mechanism using inflammation (CRP). CRP <3 mg/L → starvation (responds to refeeding); low–medium grade → inflammageing (not itself malnutrition); medium grade → cachexia (organ failure, cancer, neurodegenerative disease); CRP >100 mg/L → hypercatabolic malnutrition (sepsis, trauma, ICU). This determines whether nutrition alone will work.

Weight-loss thresholds worth quoting. Loss of 5% in 1 month, 7.5% in 3 months or 10% in 6 months is serious. BMI <22 kg/m² predicts higher one-year mortality and poorer function; ideal BMI ranges are higher in older than younger adults; BMI below the 15th percentile independently predicts 180-day mortality after hospitalisation.

Assessment is by comprehensive geriatric assessment (CGA). Systematically cover — cognition (MMSE/MoCA), depression (GDS), delirium (CAM), function (Katz, Barthel, Lawton–Brody ADL/IADL), falls and mobility (TUG, unipodal stance, SPPB), medication reconciliation and deprescribing, nutrition (BMI, MNA, weight history, swallowing test, constipation/faecal impaction screen, oral examination), and social and financial resources. Each impaired domain has a matching action — meal-texture adaptation, dental treatment, housekeeper for shopping, meals-on-wheels, caregiver education.

Anthropometry. Serial weight is the single most useful measurement — kyphosis makes height and therefore BMI unreliable. Use MUAC when there is oedema (correlates with lean mass), calf circumference, mid-arm muscle circumference; estimate height by knee-height formulae; apply percentage corrections in amputees.

Laboratory assessment. Serum albumin is practical but confounded by liver disease, proteinuria and protein-losing enteropathy; prealbumin and retinol-binding protein are more sensitive. Add CRP (grades inflammation), total lymphocyte count, haemoglobin (anaemia is one of the earliest manifestations of PEM), creatinine clearance, B12, folate, 25(OH)D, iron studies, calcium, TSH, and age-appropriate cancer screening where weight loss is unexplained.

Body composition and muscle function. DXA or BIA for fat-free mass index; CT at the L3 slice for muscle index in cancer patients; where unavailable, calf circumference is the accepted surrogate. Function is measured by handgrip strength, gait speed, chair-rise and SPPB — these predict outcome better than mass alone.

Principles and targets. First, treat reversible causes — depression, drugs, dysphagia, dentition, pain, nausea, constipation, infection, thyroid disease. Treating depression alone produces weight gain. Set requirements: approximately 30–35 kcal/kg/day, protein 1.0–1.5 g/kg/day, fluid ~1 mL/kcal (about 1.5 L/day). Avoid unnecessary therapeutic diets (low-salt, low-fat, diabetic) in the frail underweight elder — the risk of undernutrition outweighs the benefit.

Stepwise treatment ladder. (a) Food-first and nursing measures — oral and dental care, texture modification, flavour enhancement (improves intake and nutritional status in nursing-home residents), fortified/nutrient-dense foods, small frequent meals, feeding assistance, eating in company, meals-on-wheels and social support. (b) Oral nutritional supplements (ONS) — meta-analysis of 42 trials showed 2.3% weight gain and reduced mortality (RR 0.74, 95% CI 0.59–0.92); benefit was consistent when ≥400 kcal/day was given for ≥35 days to unwell, malnourished patients aged ≥75 in hospital or nursing homes. ONS also reduce pressure-ulcer incidence. No proven benefit on functional status or length of stay. (c) Exercise — progressive resistance training 2–3 times/week is the primary intervention for sarcopenia; essential amino acids stimulate muscle protein synthesis better than intact protein. Combined nutrition + early mobilisation in hospital prevents loss of functional independence even without weight gain. (d) Enteral nutrition if oral intake remains inadequate and prognosis is favourable; parenteral only if enteral is impossible (higher morbidity than enteral). PEG in nursing-home residents with severe cognitive Nutrition in the Elderly — MD Geriatric Medicine Revision Page 8 of 25 impairment does not improve 24-month survival, and aspiration pneumonia occurs at the same rate with or without tube feeding — this is an advance-care-planning discussion, not a nutritional one. (e) Orexigenic drugs — palliative only. Megestrol acetate is the best studied (appetite, weight, quality of life; oedema); corticosteroids and cyproheptadine improve appetite without weight gain; cannabinoids and thalidomide have limited evidence. (f) Monitor weight, intake charts and function; watch for refeeding syndrome (falling phosphate, potassium, magnesium) when replenishing the severely depleted.

Global burden quantified. A meta-analysis of 98 studies (n = 79,976) found the global prevalence of malnutrition in older adults to be 18.6% (95% CI 16.4–21.1%), highest in Africa at 35.7% followed by the Americas at 20.3%; by instrument, the highest prevalence was 39.9% using NRS-2002. (Salari N, et al. Public Health in Practice. 2025;9:100583.)

GLIM criteria — 5-year update. A 43-member working group reviewed >400 publications (2019–2024). No revisions were made to the weight loss, low BMI or reduced food intake/assimilation criteria; assessment of low muscle mass should be guided by experience and available technological resources, and clinical judgement may suffice for the inflammation/disease burden criterion. Construct and predictive validity are now strong. (Jensen GL, et al.

Bedside muscle-mass surrogates now validated — directly usable in Indian practice. Applying calf circumference <31 cm in both sexes, or MUAC <23 cm in men and <22 cm in women, gave 84.6% and 83.4% accuracy against SGA, with sensitivity ~89% and ~84% and specificity ~81–83%. (Shahraki Jazinaki M, et al. Front Nutr.

ONS in hospitalised older people — Cochrane individual-participant network meta-analysis. In older hospitalised people at risk of or with malnutrition, oral nutritional supplements may reduce mortality and serious adverse events compared with control at 30 days after randomisation, with little or no difference for other outcomes; the overall certainty of evidence was low to very low. This tempers the older, more confident textbook claim. (Kiesswetter E, et al. Cochrane Database Syst Rev. 2026;CD015468.)

Individualised in-hospital nutrition works, but the effect does not persist. Reaching ≥75% of estimated nutrition goals, versus lower achievement, significantly lowered the risk of adverse events and mortality; yet while individualised nutritional support during the hospital stay significantly reduced short-term mortality, there was no legacy effect on longer-term outcomes. Implication: nutritional care must be continued after discharge. (Schuetz P, et al. Lancet. 2019; Clin Nutr. 2020; ESPEN practical guideline, polymorbid medical inpatients. Clin Nutr. 2024.)

ESPEN geriatric guideline — current management standard. All older persons shall be routinely screened for malnutrition; oral intake is supported by nursing interventions, counselling, food modification and ONS; enteral nutrition is initiated if oral is insufficient and parenteral if enteral is insufficient or impossible, provided the general prognosis is favourable; dietary restrictions should generally be avoided. Low-intake dehydration should be diagnosed on serum osmolality and corrected rapidly with hypotonic fluids given as drinks, subcutaneously or intravenously depending on severity. A dedicated ESPEN update for dementia was published in 2024. (Volkert D, et al. Clin Nutr. 2022;41:958–989; Volkert D, et al. Clin Nutr. 2024.)

Sarcopenia reframed — GLIS 2024. Muscle mass, muscle strength and muscle-specific strength were all accepted as components of sarcopenia, whereas impaired physical performance was accepted as an outcome rather than a component. (Kirk B, et al. Age Ageing. 2024;53:afae052.)

Megestrol is no longer acceptable in older adults. The 2023 AGS Beers Criteria grades it avoid (strong recommendation) — minimal effect on weight, with increased risk of thrombotic events and possibly death in older adults. (AGS Beers Criteria Update Expert Panel. J Am Geriatr Soc. 2023;71.)

Indian data. In LASI, 28% of men and 25% of women aged 60 and above are underweight; the urban population is less likely to be underweight, and older adults from low economic and social strata are more likely to be underweight. Using a modified MUST, about 26% of respondents aged 45+ fell into the undernourished high-risk group, characterised by low BMI, recent hospital admission and food-insecure households. CART analysis of LASI further suggests age-specific BMI cut-offs — the underweight threshold falling from <18.5 to <17.4 for ages 60–74 and <13.3 for those 75 and above. (Khan J, et al. Sci Rep. 2023;13:12820; BMC Public Health. 2023; Singh A, Chattopadhyay A. Sci Rep.

ICMR-NIN Dietary Guidelines for Indians 2024. Seventeen guidelines addressing India’s double burden of malnutrition, with the “My Plate for the Day” model and RDA 2020 values (safe protein 0.83 g/kg/day, EAR 0.66 g/kg/day, DIAAS replacing PDCAAS). The guidelines discourage protein supplements and high-protein concentrates for muscle building, citing bone mineral loss and kidney damage with prolonged intake. (ICMR-NIN. Dietary Guidelines for Indians. 2024.)