Subjective Global Assessment (SGA)
The Subjective Global Assessment is a structured clinical tool that combines history and physical examination to diagnose malnutrition and to tell it apart from cachexia and sarcopenia.
Plain English
Patient-Friendly Explanation
The Subjective Global Assessment, usually shortened to SGA, is a way for a clinician to work out whether a person is malnourished by taking a careful history and examining them, without relying on a single blood test. It was developed in 1982 for surgical patients and has been refined since. The history covers how much weight has been lost and over what period, how the person has been eating, whether there have been symptoms such as vomiting, diarrhoea or poor appetite, how much their physical function has changed, and how much the underlying illness adds to their nutritional needs. The examination looks at subcutaneous fat, muscle wasting in the temples, shoulders and hands, and swelling in the ankles or abdomen. From those findings the patient is classed as well nourished, moderately or suspected malnourished, or severely malnourished. The value of the tool is that it captures the whole clinical picture rather than one number, and it has been shown to predict complications, length of stay and death. It is also useful for a specific problem: not all weight loss is good news. When someone loses weight without meaning to, the SGA helps the clinician decide whether malnutrition from poor intake or absorption is the cause, as opposed to cachexia from a serious illness or sarcopenia of ageing, each of which calls for a different response. A version for children, the Subjective Global Nutritional Assessment, is also available.
Medical
Clinical Definition
The Subjective Global Assessment is a clinical nutrition assessment instrument that diagnoses malnutrition from two components. The history records weight change over the preceding six months, change in dietary intake, the presence and duration of gastrointestinal symptoms, functional capacity and the metabolic demand of the underlying disease. The physical examination assesses loss of subcutaneous fat, muscle wasting, and oedema or ascites. Patients are then rated as A (well nourished), B (moderately or suspected malnourished) or C (severely malnourished). Developed by Baker and colleagues in 1982, the tool has been validated internationally and reliably predicts infectious and non-infectious complications, length of hospital stay and mortality in surgical, medical and critical care populations, including mechanically ventilated patients. A revised form published by Duerksen and colleagues in Nutrition in Clinical Practice in 2021 clarifies the concepts behind the diagnosis and deliberately distinguishes malnutrition from cachexia and from sarcopenia, which share features of wasting but respond differently to nutrition support. In obesity practice the SGA is used to detect coexisting or secondary malnutrition, and as a companion to screening tools such as the Malnutrition Universal Screening Tool, which screens for risk while the SGA confirms and grades the diagnosis. A validated paediatric adaptation, the Subjective Global Nutritional Assessment, is available for children.
Key Insight
Why It Matters
Not every patient who loses weight is doing well, and the SGA is the tool that separates planned weight loss from malnutrition. It matters most after bariatric surgery, in older adults, and where an unintended fall in weight accompanies illness, because it distinguishes malnutrition, cachexia and sarcopenia and directs the right intervention. Its weakness is that it depends on clinical judgement, so training and consistency matter.
Sources
Reviewed against standard medical references.
Medically reviewed by
Family Physician & Registered Acupuncturist, Accord Medical Clinic. MBBS (NUS), Graduate Diploma in Family Medicine (NUS), Graduate Diploma in Acupuncture (Singapore College of TCM).
Last reviewed: October 2026
This page is general health education, not medical advice. Whether any treatment is appropriate for you is a decision made in consultation after assessment.
