# Underweight - Category: chronic - Review status: reviewed (every claim checked against a document named on this page) - Sources: Anorexia and Cachexia - StatPearls - NCBI Bookshelf (NBK430977) - https://www.ncbi.nlm.nih.gov/books/NBK430977/ · ICPC-3 (WONCA International Classification of Primary Care, 3rd edition) class TS50 - condition scope only, no dose · Egyptian drug register - availability only, no dose - Verified date: 2026-09 ## Verified against - Anorexia and Cachexia - StatPearls - NCBI Bookshelf (NBK430977) - https://www.ncbi.nlm.nih.gov/books/NBK430977/, Treatment / Management (protein 1-1.5 g/kg/day; supplements 200-300 kcal and 10-20 g protein per 100 mL; EPA 1.8-2.2 g daily; no dose stated for any appetite stimulant) - Egyptian drug register (megestrol only as an unlicensed import; anamorelin and dronabinol absent; mirtazapine and olanzapine stocked) ## Treatment metadata - High-energy, high-protein nutrition (First-line treatment) - Find the cause, and the drugs that have no stated dose (Referral & Advice) ## Complete treatment card ```text UNDERWEIGHT Sources: Anorexia and Cachexia - StatPearls - NCBI Bookshelf (NBK430977) - https://www.ncbi.nlm.nih.gov/books/NBK430977/ · ICPC-3 (WONCA International Classification of Primary Care, 3rd edition) class TS50 - condition scope only, no dose · Egyptian drug register - availability only, no dose Review status: REVIEWED against Anorexia and Cachexia - StatPearls - NCBI Bookshelf (NBK430977) - https://www.ncbi.nlm.nih.gov/books/NBK430977/, Treatment / Management (protein 1-1.5 g/kg/day; supplements 200-300 kcal and 10-20 g protein per 100 mL; EPA 1.8-2.2 g daily; no dose stated for any appetite stimulant), Egyptian drug register (megestrol only as an unlicensed import; anamorelin and dronabinol absent; mirtazapine and olanzapine stocked) (2026-09) IS IT THIS? - reference only, to read alongside your own examination SYMPTOMS - what the patient reports (5) - The story is weight loss the patient never intended, poor appetite and feeling full early [poor appetite · weight loss] - Weight keeps falling even when intake looks adequate or has gone up - Tiredness, falling physical function, less exercise capacity and trouble with daily activities [fatigue] - Part of that tiredness is anaemia from the underlying chronic illness [anaemia · fatigue] - It arrives late in cancer or another chronic disease, so the history usually confirms a suspicion already held SIGNS - what you find (4) - Marked muscle wasting, especially in the limbs, giving a gaunt look and a weak grip [muscle wasting] - Less fat under the skin, with shoulders, collarbones, ribs, hips and cheeks standing out - BMI is low, typically under 20 kg/m2 - Look for pallor, swelling or enlarged organs from the illness underneath [pallor] TESTS (10) - The definition is unintended weight loss over 5%, or a BMI under 20 kg/m2, alongside continuing muscle loss, fatigue, poor appetite and declining function - Work out baseline calorie and protein intake and the needs on top, allowing for raised resting energy use - Bioelectrical impedance or DEXA quantifies muscle mass and fat stores and tracks change - Grip strength below 20 kg in men or below 14 kg in women shows impaired muscle function and predicts poor outcomes - Albumin, prealbumin and transferrin gauge protein status and nutritional reserve - A raised CRP points to inflammation driving the wasting, and tracks with how bad it is - A full blood count picks up anaemia and may hint at inflammation or infection - Electrolytes with liver and kidney function show malnutrition and organ damage - Check testosterone and thyroid hormones, which can worsen weight loss, wasting and fatigue - Look for deficiency of iron, vitamin D, B12 and folate, all common in chronic disease IF NOT THIS - what else fits (7) - Anorexia nervosa and other eating disorders lose weight severely but without the muscle wasting or metabolic changes - Plain starvation from too little food strips fat and lean mass without inflammation, and recovers with feeding - Heart failure, kidney failure, cancer and COPD cause malnutrition without the inflammatory pattern, though they can progress into it - Sarcopenia is age-related muscle loss with functional decline, but without inflammation or big weight loss - Most who are cachectic are also sarcopenic, but most with sarcopenia are not cachectic - Endocrine disease, malabsorption and psychiatric disorders also belong here - History, examination and relevant blood tests usually separate them Source StatPearls "Anorexia and Cachexia" - disease-level clinical article Status traced to the source above Rx: First-line treatment - the part with a stated amount | The cause, and the appetite drugs FIRST-LINE TREATMENT - THE PART WITH A STATED AMOUNT 1. HIGH-ENERGY, HIGH-PROTEIN NUTRITION (FIRST-LINE TREATMENT)[1st line] Adult Protein 1 to 1.5 g per kg of body weight daily, from fortified food and oral supplements. Commercial oral supplements provide about 200 to 300 kcal and 10 to 20 g of protein per 100 mL. In renal failure, keep protein under 1.3 g per kg daily - continuous, alongside treatment of the underlying cause Peds This article is about adult anorexia and cachexia and gives no paediatric figures. An underweight child is a different problem - growth faltering - and is assessed on growth centiles. Choice Why nutrition leads rather than a drug: the article names appetite stimulants and anabolic agents but states no dose for any of them, and attaches serious harms to the two that are used most. Under the rule that an amount must come from a named source, there is nothing to print for them - so they are listed on the row below without doses. Source Anorexia and Cachexia - StatPearls - NCBI Bookshelf (NBK430977) - https://www.ncbi.nlm.nih.gov/books/NBK430977/, Treatment / Management - verbatim: "High- protein diets, typically providing 1 to 1.5 g/kg of body weight daily, help maintain adequate nutritional status and stabilize weight, improve lean body mass, and enhance overall quality of life." "Commercially available oral supplements generally provide 200 to 300 kcal and 10 to 20 g of protein per 100 mL." "Patients with renal failure should consume less than 1.3 g of protein per kg of body weight daily." Why This is the treatment with a stated amount, and it is the one primary care delivers. The article: "Nutritional interventions should focus on high-energy, high-protein diets with fortified foods and oral supplements when necessary", combined with exercise tailored to the patient. It is deliberately first here because the drugs that stimulate appetite have no stated dose in the source and poor evidence behind them - see the row below. Caution Cachexia is not starvation and food alone will not reverse it. The article: the metabolic dysregulation, systemic inflammation, alimentary tract dysfunction and anorexia together make "conventional nutritional support ineffective in reversing the condition." Nutrition stabilises weight and preserves function; treating the underlying disease is what changes the course. Do not escalate to tube or drip feeding for this alone. The article states plainly: "No evidence supports routine enteral tube feeding supplementation or parenteral nutrition." Know what you are actually looking at. The article's cachexia definition: weight loss of more than 5% in 6 months, or a BMI under 20 kg/m2 with ongoing loss of more than 2%, plus at least one of - anorexia or reduced intake, reduced grip strength, or an inflammatory marker such as C-reactive protein above 5 mg/L. Eicosapentaenoic acid is the one supplement with a number attached, and the evidence is weak. The article: "Studies have shown increased body weight or muscle mass with an eicosapentaenoic acid dose between 1.8 and 2.2 g daily. However, adverse effects include gastrointestinal distress, liver dysfunction, and bleeding tendencies, which limit its use", and ASCO guidelines note further research is needed. Vitamin D is mentioned as supporting muscle protein synthesis, without a dose. THE CAUSE, AND THE APPETITE DRUGS 2. FIND THE CAUSE, AND THE DRUGS THAT HAVE NO STATED DOSE (REFERRAL & ADVICE)[2nd line] Adult Being underweight is a finding, not a diagnosis. The GP's task is to identify and treat the underlying cause - malnutrition, chronic disease, an eating disorder, an overactive thyroid, malignancy - rather than prescribe for the weight itself. The article's own framing is that cachexia accompanies advanced cancer, chronic infection, COPD, renal failure, heart failure and late-stage inflammatory autoimmune disease. - Refer Peds Children follow the same pathway: recognise and refer. No primary-care medicine is implied. Source No dose - the causes to find, and the appetite drugs for which Anorexia and Cachexia - StatPearls - NCBI Bookshelf (NBK430977) - https://www.ncbi.nlm.nih.gov/books/NBK430977/, Treatment / Management states no amount Why Being underweight is a finding, not a diagnosis. The GP's task is to identify and treat the underlying cause - malnutrition, chronic disease, an eating disorder, an overactive thyroid, malignancy - rather than prescribe for the weight itself. The article's own framing is that cachexia accompanies advanced cancer, chronic infection, COPD, renal failure, heart failure and late-stage inflammatory autoimmune disease. Caution RED FLAG - Unintentional significant weight loss can be the first sign of malignancy, tuberculosis, or another serious systemic illness. Investigate the cause before treating the weight. The appetite stimulants, with the article's own verdicts and no doses - because it states none. Progesterone analogues (megestrol acetate, medroxyprogesterone acetate) stimulate appetite, but megestrol "is associated with adverse effects of fluid retention, thromboembolic events, and an increased risk of death", and in Egypt the only entry, MEGACE 160 mg, is flagged an unlicensed import. Corticosteroids such as dexamethasone "can improve appetite in the short term, but risks of immunosuppression, osteoporosis, fluid retention, and hypertension limit chronic use." Olanzapine and mirtazapine are the better-tolerated options and both are stocked in Egypt, but again with no dose in the source. The article: olanzapine "has been shown to increase appetite and weight when administered in small doses, with minimal adverse effects" and its antiemetic effect helps chemotherapy nausea; mirtazapine "can be useful in patients with depression-related anorexia", though "evidence for the overall efficacy of mirtazapine in treating cancer cachexia is more limited compared to olanzapine." "Small doses" is not a dose, so none is printed. Anamorelin, the ghrelin receptor agonist the article describes as promising, is not approved by the FDA for cancer cachexia and has no entry in the Egyptian register at all. Neither does dronabinol. They are named so you know they exist, not as options here. No single drug reverses cachexia. The article: "Although no single therapy completely reverses cachexia, treatment can alleviate symptoms and improve quality of life." That is the honest thing to tell the patient and the family. Prices are indicative (dataset snapshot 2026-06); verify with the pharmacy. ``` --- Dawaa Reference is a reference for prescribers, not a medical device, and does not replace clinical judgement. [Privacy policy](/privacy)