Weight Loss, Muscle Loss and Sarcopenia in Older Adults

Unintentional weight loss is usually defined as losing about 5% or more of your body weight over 6 to 12 months without trying, for example about 4 kg in a person weighing 80 kg. Sarcopenia is a progressive loss of muscle strength and muscle mass, as defined by the European consensus (EWGSOP2): low muscle strength is the key sign, confirmed by low muscle quantity or quality, and severe when physical performance such as walking speed is also poor. Malnutrition in older adults is defined (by the GLIM criteria) by weight loss, low body mass index or low muscle mass together with reduced food intake or absorption, or illness-related inflammation. These problems often occur together and feed on one another.

Unintentional weight loss affects a notable share of older adults, especially those in hospital, in care homes, or with chronic illness. Sarcopenia becomes more common with age and is more frequent in people with diabetes, liver, kidney, heart or lung disease, cancer, and in those who are inactive. It can also occur in people with obesity (sarcopenic obesity), where body weight hides low muscle.

Causes are many and often several at once: cancer (including cancers of the food pipe, stomach, pancreas, bowel and liver), digestive diseases that reduce absorption (coeliac disease, inflammatory bowel disease, chronic pancreatitis, bacterial overgrowth), swallowing and dental problems, depression and grief, dementia, overactive thyroid, diabetes, heart, lung or kidney disease, infections such as tuberculosis, alcohol, and medicines (some cause nausea, dry mouth or loss of appetite, such as metformin, digoxin, some antibiotics and antidepressants, and GLP-1 medicines). Social causes are also important: loneliness, poverty, difficulty shopping or cooking, and restrictive diets. With ageing, appetite falls, muscle responds less to protein and exercise (anabolic resistance), and inactivity speeds loss. Muscle loss itself reduces strength and walking speed and increases falls, fractures, hospital stays and dependence.

The doctor confirms the weight loss using old records, then asks about appetite, swallowing, teeth, bowel habit, mood, memory, alcohol, medicines and food access, and examines you, including the mouth, thyroid, abdomen and lymph nodes. First-line tests are typically a blood count, inflammation markers, kidney, liver and thyroid tests, calcium, blood sugar, iron/B12/folate, a coeliac blood test when suitable, a urine test and a chest X-ray. Further tests such as gastroscopy, colonoscopy or CT scan are chosen by symptoms and findings rather than by a fixed list; if the first tests are normal, close follow-up with repeat weighing is reasonable. Simple screening tools for malnutrition risk (such as the MUST or MNA-SF) and for sarcopenia (the SARC-F questionnaire, grip strength, a timed chair-stand and walking speed) are used; scans measuring muscle (DXA) may be used in some centres. A dietitian, a swallowing therapist and a physiotherapist often take part.

When a cause is found and treated, weight and strength often improve; early action matters because muscle lost in illness is slow to regain. Many older adults regain strength with exercise and better nutrition even in their 80s and 90s. When the cause is a serious illness, early diagnosis gives the most options.