Unexplained Weight Loss in Teenage Males: What to Know

Weight can change during adolescence as height, muscle and appetite develop, but loss that is not intended should still be discussed with a clinician. Possible contributors include eating less because of stress, low mood, dental problems, nausea, or a restrictive eating pattern. Increased activity without enough food can also reduce weight.

Some health conditions present with weight loss. Type 1 Diabetes may cause marked thirst, frequent urination, tiredness or blurred vision. Hyperthyroidism can present with heat intolerance, sweating, a racing heartbeat or shakiness. Coeliac Disease may cause abdominal symptoms or poor absorption, while Crohn's Disease can cause ongoing diarrhoea, abdominal pain and reduced appetite. Depression may present with appetite and weight changes alongside low mood or loss of interest.

Less common but important causes include Tuberculosis or HIV Infection, particularly when there are persistent fevers, night sweats, cough, swollen glands or relevant exposure risks. Weight loss alone cannot identify the cause.

Arrange an appointment with a family doctor or paediatric clinician if the loss is ongoing, noticeable, or not explained by a planned change in food or exercise. Bring a simple record of appetite, meals, activity, bowel habits, thirst, urination, sleep and other symptoms. Include any medicines, supplements or recent illness.

Do not start a high-calorie supplement or force meals without advice. Offer regular balanced meals and fluids, and speak privately with the teenager about stress, body image, bullying and eating concerns. A clinician may check growth over time, examine the abdomen and thyroid, and decide whether blood or urine tests are appropriate.

Seek urgent medical help for weight loss with severe thirst and frequent urination, repeated vomiting, deep or rapid breathing, confusion, fainting, severe abdominal pain, blood in vomit or stool, or inability to keep fluids down. These symptoms can signal a serious problem such as untreated diabetes or significant dehydration.

Prompt assessment is also needed for coughing blood, breathing difficulty, persistent fever, drenching night sweats, marked weakness, or thoughts of self-harm. If eating is being deliberately restricted, bingeing or followed by purging, tell a trusted adult and arrange professional support quickly.

Ask: Could growth and puberty explain any of this change? Which symptoms or patterns should we monitor? Could digestion, thyroid function, blood sugar, infection, mood or eating concerns be contributing? What tests are appropriate, and when should we return if weight continues to fall?