The signs and symptoms of malnutrition are diverse because there are many different types of malnutrition.
In undernutrition, the initial symptoms might be a lack of interest in food, fatigue, irritability, and poor concentration. There might be unintentional weight loss, a low body-fat percentage, and sometimes mental health conditions like anxiety or depression. Muscle weakness could result in difficulty with normal tasks like getting dressed or taking a walk. Very low intake or poor absorption of food could result in low blood sugar levels and electrolyte disturbances.[1]
In micronutrient malnutrition, the symptoms could be related to the inappropriate levels of a specific vitamin or mineral. For example, a low level of vitamin B12 could cause peripheral neuropathy,[2][3] and a high calcium level could cause abdominal discomfort and bone pain,[4] while a low iron level might cause severe fatigue.[5]
In overweight and obesity, malnutrition occurs due to an excess of energy intake, and this can cause joint pain and fatigue. It can also have a negative effect on mental health. Chronic conditions like type 2 diabetes, high blood pressure, and high cholesterol can develop in people with overweight and obesity, and this increases the risk of cardiovascular disease, stroke, and chronic kidney disease.[6]