Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Nutrition, weight loss and malnutrition
Medicine of older adults · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Severe malnutrition or refeeding danger
Shock, severe dehydration, hypoglycaemia, electrolyte disturbance, inability to swallow, gastrointestinal obstruction, uncontrolled vomiting or very high refeeding risk can cause cardiac, respiratory and neurological deterioration.
Action: Use ABCDE and glucose, obtain urgent phosphate, potassium, magnesium, renal and ECG assessment, treat the acute cause and begin nutrition through a specialist plan with thiamine, cautious energy delivery and close biochemical monitoring when refeeding risk is present.
Overview
Identify clinically important undernutrition and unexplained weight loss early, distinguish poor intake from disease and absorption causes, and restore nutrition safely through food, oral, enteral or parenteral support matched to goals and function.
Establish trajectory rather than one measurement. Record current and usual weight, timing and percentage loss, clothing or ring fit, appetite, portions, drinks and days of minimal intake. Interpret weight with oedema, ascites, dehydration and diuresis. Ask whether the person can shop, cook, open packages, use cutlery and remain alert through a meal; observed intake often differs from a meal placed nearby.
Use a validated screen such as MUST and act on the score, but do not let BMI obscure loss in a person with obesity or oedema. Examine muscle wasting, fat loss, mouth, teeth, swallowing, hydration, oedema, skin and functional strength. Obtain collateral from family, carers and food charts when cognition or recall limits accuracy.
Search for cause in parallel with support. Ask dysphagia, odynophagia, early satiety, vomiting, diarrhoea, steatorrhoea, bleeding, pain, bowel change, fever, night sweats, cough and endocrine symptoms. Screen mood, cognition, alcohol use and bereavement. Review medicines causing nausea, dry mouth, taste change, constipation, sedation or appetite suppression. Assess finances, food supply and meal assistance privately where safeguarding concern exists.
Practice
Two practice questions
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Medicine of older adultsOriginal SBA
Recognising refeeding risk
An 82-year-old with a BMI of 15.5 kg/m² has eaten almost nothing for 12 days. What is the safest nutrition approach?
Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Select investigations from the phenotype. A common baseline includes FBC, renal and electrolytes, liver profile, adjusted calcium, CRP or ESR, thyroid and glucose, with iron, B12, folate, vitamin D or coeliac testing as indicated. Use chest imaging, endoscopy, CT, stool or cancer referral according to symptoms; a broad normal blood panel does not explain continuing weight loss.
Set goals with the person: weight stabilisation, strength, wound healing, treatment tolerance, comfort or safer swallowing. Estimate energy, protein and fluid requirements with dietetics when risk is substantial, renal or hepatic disease complicates targets, or refeeding is possible. Avoid generic high-protein advice in advanced kidney disease without an individual plan.
Food-first management improves energy density without making meals unmanageably large: fortify familiar foods, add snacks and nourishing drinks, treat pain, nausea, constipation and dry mouth, and provide dentures, adaptive cutlery or feeding assistance. Preserve cultural and personal choice. Protected mealtimes are useful only if staff still provide required prompting and help.
Oral nutritional supplements are prescribed when an assessed deficit remains after reasonable food measures or when rapid support is needed. Choose flavour, volume, texture, fibre and nutrient profile for swallowing, diabetes, renal state and preference. Explain timing so supplements do not replace tolerated meals unintentionally. Record who supplies and monitors them and stop or adapt when goals are met or they are unused.
When swallowing is unsafe or intake remains inadequate, multidisciplinary assessment selects route. A nasogastric tube can provide short-term enteral support when gut function is preserved; gastrostomy decisions consider expected duration, disease trajectory, risks, capacity and goals. Advanced dementia alone is not an automatic indication for tube feeding, and NICE advises against routine enteral feeding in severe dementia unless a potentially reversible comorbidity is responsible.
Identify refeeding risk before meaningful nutrition begins. NICE high-risk criteria include very low BMI, major recent weight loss, prolonged little intake or low phosphate, potassium or magnesium, with additional combined risk factors. Start at the guideline-specified reduced energy rate under skilled care, give thiamine and balanced vitamin supplementation, replace electrolytes and monitor fluid balance without delaying correction until levels become profoundly abnormal.
Integrate physical recovery. Resistance and mobility rehabilitation helps convert supplied nutrition into strength and function. Occupational therapy, speech and language therapy, dentistry, pharmacy, social care and community services address real barriers. At transition, communicate current weight, route, texture, assistance, supplement, refeeding status, goals and review owner.
Key points
Screen all hospital inpatients on admission and weekly, and screen community or care-home patients when clinical concern exists, using a validated tool such as MUST.
NICE defines malnutrition risk through low BMI, significant unintentional weight loss or little or no nutritional intake, interpreted with disease and fluid state.
First-line assessment measures weight trajectory, BMI, actual intake, swallowing, dentition, gastrointestinal symptoms, function, mood, cognition, medicines and food access.
Do not attribute weight loss to ageing; investigate cancer, infection, endocrine, organ, gastrointestinal, dental, psychiatric and social causes from the phenotype.
Food-first care enriches familiar meals, improves meal timing and assistance, treats symptoms and preserves choice; dietitians calculate individual energy and protein needs.
Use oral nutritional supplements when ordinary and fortified food cannot meet assessed needs, with a defined indication, prescription and response measure.
Enteral feeding is considered when the gastrointestinal tract works but oral intake is unsafe or inadequate; parenteral support is reserved for an inaccessible or non-functioning tract.
Before feeding, identify refeeding risk and check phosphate, potassium, magnesium, glucose, renal status and fluid balance.
Aetiology
01
Reduced intake
Poor appetite, pain, depression, dementia, delirium, dentition, dysphagia, breathlessness and medicine effects reduce eating and drinking.
02
Disease-related catabolism
Cancer, infection, inflammatory disease and organ failure increase energy expenditure and muscle breakdown while suppressing appetite.
03
Malabsorption or nutrient loss
Coeliac disease, pancreatic insufficiency, bowel disease, diarrhoea and renal or gastrointestinal losses prevent adequate nutrient retention.
04
Social and functional barriers
Poverty, loneliness, inaccessible shops, inability to cook, carer gaps and unsuitable meal assistance reduce real intake.
Pathophysiology
1
Negative energy balance
Energy intake below expenditure consumes fat and muscle stores, reducing strength, immunity, thermoregulation and wound healing.
2
Anabolic resistance
Older muscle responds less effectively to small protein doses and inactivity, accelerating sarcopenia during illness and bed rest.
3
Micronutrient depletion
Deficient iron, B12, folate, thiamine, vitamin D and electrolytes impair blood, neurological, skeletal and cardiac function.
4
Refeeding shifts
Insulin release after renewed carbohydrate drives phosphate, potassium and magnesium into cells, causing arrhythmia, weakness, fluid overload and neurological injury.
5
Frailty feedback
Weakness makes shopping, cooking and self-feeding harder, further reducing intake and turning acute weight loss into persistent dependency.
Clinical features and red flags
Unintentional weight-loss pattern
Clothes loosen, portions shrink and muscle strength falls despite no deliberate dieting.
Hidden obesity-associated malnutrition
A high BMI can coexist with major recent loss, low intake and severe muscle depletion.
Disease-related catabolism
Inflammation, cancer or organ failure produces weight and muscle loss despite attempts to increase food.
Unsafe intakeRed flag
Choking, wet voice, fatigue or recurrent chest infection suggests dysphagia and aspiration danger.
High refeeding riskRed flag
Very low BMI, prolonged starvation, substantial recent loss or depleted electrolytes requires a controlled nutrition plan.
Social intake failure
Food is unavailable, inaccessible or left uneaten because shopping, cooking, cognition or assistance has failed.
Red flags requiring action
Dysphagia, choking, wet voice, recurrent chest infection or inability to manage saliva requires urgent swallowing and airway assessment.
Unintentional weight loss with mass, bleeding, persistent pain, anaemia, jaundice or change in bowel habit requires expedited cancer investigation.
Confusion, ophthalmoplegia, ataxia or alcohol dependence with poor intake requires immediate parenteral thiamine consideration.
Investigations
01MUST and weight trajectoryFirst stepFirst line
Why
Identify malnutrition risk and urgency first line.
Interpretation and limitations
Combine BMI, percentage unplanned loss and acute intake effect, adjusting interpretation for oedema, dehydration and measurement reliability.
02Observed intake and functional assessment
Why
Find practical reasons meals are not consumed.
Interpretation and limitations
Record food and fluid actually taken, meal duration, alertness, dexterity, posture, assistance and access rather than tray delivery.
03Swallowing and oral assessment
Why
Determine whether oral nutrition is safe and feasible.
Interpretation and limitations
Examine mouth and dentition and obtain speech and language assessment for choking, wet voice, fatigue or recurrent chest disease.
04Baseline laboratory profile
Why
Identify cause, consequences and feeding safety.
Interpretation and limitations
Use FBC, renal, electrolytes, liver, calcium, inflammation, thyroid and glucose, adding deficiencies and disease tests from the history.
05Refeeding biochemistry
Why
Classify and monitor metabolic risk.
Differential diagnosis
01
Malignancy
Site-specific symptoms, anaemia, lymphadenopathy, bleeding or persistent unexplained loss requires the corresponding urgent diagnostic pathway without nutritional delay.
02
Depression or dementia
Low mood, apathy, executive failure and forgetting meals can reduce intake but do not exclude concurrent physical disease.
03
Endocrine and metabolic disease
Hyperthyroidism, diabetes, adrenal disease, hypercalcaemia and chronic organ dysfunction cause weight loss through distinct systemic mechanisms.
04
Swallowing or gastrointestinal disease
Oropharyngeal dysphagia, obstruction, ulceration, malabsorption and pancreatic disease require targeted examination, imaging or endoscopy according to the symptom pattern.
05
Fluid-change artefact
Diuresis, oedema and dehydration alter measured weight, so trajectory must be interpreted with examination and intake history.
Management
01First-line nutrition routeScreen, diagnose and support togetherFirst stepFirst lineWeight loss, low intake, frailty or acute illness raises malnutrition concern.+
1Measure trajectory and MUST, assess actual intake, swallowing, function and immediate refeeding or dehydration danger.
2Investigate disease, medicine, mood, cognition, oral and social causes while setting person-centred nutrition goals.
3Begin food-first or appropriate nutrition support with dietetic oversight and a defined weight, intake and functional review.
02Refeeding-risk routeRestore nutrition without metabolic collapseNICE high-risk criteria or depleted phosphate, potassium or magnesium are present.+
1Obtain baseline biochemistry, ECG and fluid assessment and involve clinicians skilled in nutrition support.
2
Complications
01
Sarcopenia and falls
Loss of muscle power impairs transfers and balance, increasing fracture, fear, immobility and care dependence during and after illness.
02
Pressure injury and poor healing
Protein-energy and micronutrient deficits weaken tissue tolerance, collagen synthesis and immune response during sustained pressure and wound repair.
03
Infection and treatment intolerance
Impaired immunity and reserve increase infection, surgical complications, medicine toxicity and delayed recovery from acute illness.
04
Refeeding syndrome
Rapid unsupervised nutrition can precipitate hypophosphataemia, arrhythmia, heart failure, respiratory weakness, delirium and death soon after feeding begins.
05
Loss of independence
Weakness, fatigue and inability to prepare food can create a persistent need for meal support, rehabilitation or alternative care.
Monitoring and follow-up
Repeat weight under comparable conditions and interpret it with oedema, hydration and intake.
Record food, fluid, supplement and tube-feed delivery against the prescribed target and reasons for missed intake.
During refeeding, follow phosphate, potassium, magnesium, glucose, renal status and fluid balance at the specialist-defined frequency.
Track grip or chair-rise strength, mobility, ADLs, wound healing and treatment tolerance alongside body weight.
Confirm community supply, meal assistance and named dietetic or medical ownership after every transition.
Special situations
Obesity does not protect
Substantial muscle and nutrient loss can be missed when BMI remains above a conventional low threshold.
A tray is not intake
Meal delivery without posture, alertness, opening, prompting and assistance can leave nutrition effectively absent.
Albumin is not a nutrition score
Inflammation, liver disease, renal loss and fluid state alter albumin independently of energy intake.
Nutrition and loading work together
Protein supports recovery, but progressive movement supplies the stimulus needed to rebuild functional muscle.
Route decisions are goal decisions
Tube feasibility alone does not establish benefit; trajectory, capacity, duration and the person's values remain central.
Common pitfalls
01
Calling unintentional weight loss a normal consequence of ageing.
02
Using BMI alone and missing rapid loss in obesity or oedema.
03
Prescribing supplements without checking whether they are opened and consumed.
04
Starting full nutrition rapidly after prolonged starvation without refeeding precautions.
05
Giving generic high-protein advice in advanced kidney or liver disease.
06
Treating low albumin as a specific diagnostic test for malnutrition.
07
Completing cancer blood tests while ignoring persistent site-specific symptoms.
08
Discharging a feeding plan without supply, assistance and named monitoring.
For high refeeding risk, NICE advises slow initiation with thiamine and multivitamin support and specialist biochemical and fluid monitoring.
Review weight, intake, strength, wounds and the underlying cause; nutrition support without functional rehabilitation may not restore independence.
BMI below 16 kg/m², minimal intake for more than ten days or major recent weight loss signals high refeeding risk under NICE criteria.
Severe depression, neglect, food insecurity, controlling care or inability to access meals raises urgent mental-health, safeguarding and social-care needs.
Oedema, dehydration, pressure injury or abrupt functional decline may be a late malnutrition presentation even when body weight appears normal.
Interpretation and limitations
Check phosphate, potassium, magnesium, glucose, renal status and fluid balance before and during feeding, with ECG when clinically indicated.
06Targeted cancer or gastrointestinal tests
Why
Investigate persistent unexplained weight loss.
Interpretation and limitations
Choose urgent referral, imaging, endoscopy, coeliac or pancreatic testing from site-specific symptoms and signs rather than age alone.
07Comprehensive geriatric assessment
Why
Integrate frailty, cognition and community delivery.
Interpretation and limitations
Assess mobility, mood, medicines, continence, sensory loss, home circumstances, carers, finances and the person's goals.
Give thiamine and balanced vitamins and start energy cautiously at the current guideline rate while replacing electrolytes.
3Monitor fluid, glucose, phosphate, potassium, magnesium, cardiorespiratory and neurological status and advance only when safe.
03Route escalationMatch support to gut and swallow functionEscalationOral intake remains unsafe or insufficient despite assistance and food measures.+
1Use speech and language and dietetic assessment to determine safe textures, likely duration and whether the gastrointestinal tract functions.
2Consider oral supplements, short-term nasogastric or longer enteral access through shared goals and capacity assessment.
3Use parenteral nutrition only when enteral intake is inaccessible, insufficient or unsafe and monitor line and metabolic complications.
04Community recoveryMake nutrition feasible after dischargeThe plan depends on shopping, preparation, prompting or specialist feeding outside hospital.+
1Specify texture, route, supplements, assistance, equipment, food access and who weighs and monitors the person.
2Coordinate GP, dietitian, pharmacy, speech and language therapy, dentistry, rehabilitation, carers and social support.
3Review intake, weight, strength, wounds and cause progression and adapt burdensome support when goals change.
Key medicines and prescribing safety1 treatment · regimens, roles and cautions+
Prevents thiamine-deficiency neurological and cardiac complications when nutrition restarts after prolonged depletion.
Oral thiamine for high refeeding risk
Give thiamine 200 to 300 mg orally daily immediately before and during the first 10 days of feeding, with a balanced multivitamin or trace-element supplement, under the NICE refeeding protocol.
Possible Wernicke encephalopathy requires immediate parenteral treatment rather than oral prophylaxis; correct magnesium and monitor fluid and electrolytes with specialist input.