Unexplained weight loss

Overview

Unexplained weight loss is when you lose weight without trying and do not know why. It usually means losing a significant amount of weight (for example, more than 5% of your body weight) over 6 to 12 months. This is not weight loss from dieting or exercise. It can be a sign that something in your body is not working correctly.

Unexplained weight loss is less common than intentional weight loss, but it does happen. It is more common in older adults and people with chronic health conditions.

Unexplained weight loss can affect anyone, but it is more common in people over 60, those with chronic illnesses like diabetes or thyroid problems, and people who have an infection or cancer.

Symptoms

Common symptoms

• Losing weight without trying, especially more than 5% of your body weight in 6 to 12 months.
• Loss of appetite or feeling full quickly after eating.
• Feeling very tired or weak.
• Fever or night sweats.
• Changes in bowel habits, such as diarrhea or constipation.

Symptoms in children

• Poor growth or not gaining weight as expected.
• Lack of energy or being less active than usual.
• Irritability or changes in mood.
• Frequent infections or illnesses.

Symptoms in older adults

• Weight loss over several months without trying.
• Loss of muscle strength or feeling frail.
• Difficulty swallowing or changes in taste.
• Memory problems or confusion.

Causes

Main causes

• Uncontrolled diabetes (type 1 or type 2).
• Overactive thyroid (hyperthyroidism) – the thyroid gland makes too much hormone.
• Infections such as tuberculosis, HIV, or chronic infections.
• Digestive disorders like Crohn’s disease, ulcerative colitis, or celiac disease.
• Cancer – weight loss can be an early sign of some cancers.

When to see a doctor

See a doctor urgently if:

• If you have lost a lot of weight quickly (more than 5% in less than 6 months) and feel very unwell.
• If you have severe symptoms like high fever, severe pain, or confusion.

Book a routine appointment if:

• If you notice you are losing weight without trying, even if it is gradual.
• If you have other symptoms like fatigue, changes in appetite, or bowel problems.

Diagnosis

Your doctor will ask about your medical history, symptoms, and eating habits. They will do a physical exam and may order tests to find the cause.

Tests that may be done

• Blood tests – to check for diabetes, thyroid problems, infections, or inflammation.
• Urine tests – to look for signs of infection or kidney problems.
• Imaging tests like X-rays, CT scan, or ultrasound – to look for tumors or other issues.
• Stool tests – if you have digestive symptoms.

Treatment

Treatment for unexplained weight loss focuses on the underlying cause. Once your doctor knows what is causing the weight loss, they will recommend a plan to address it.

Self-care at home

• Eat small, frequent meals throughout the day to increase calorie intake.
• Choose nutrient-dense foods like whole grains, lean proteins, fruits, and vegetables.
• Add healthy fats like olive oil, nuts, or avocado to meals.
• Drink plenty of fluids, but avoid filling up on water before meals.
• Keep a food diary to track what you eat and any symptoms.

Living with this condition

Managing unexplained weight loss involves addressing the cause and supporting your body. Weigh yourself regularly, but do not obsess over numbers. Focus on how you feel and your energy levels.

Lifestyle tips

• Eat small, frequent meals with protein and healthy fats.
• Stay active with light exercise like walking or stretching, as tolerated.
• Manage stress through relaxation techniques like deep breathing or meditation.
• Get enough sleep to help your body recover.
• Quit smoking and limit alcohol.

Prevention

Not all causes of unexplained weight loss can be prevented, but you can reduce your risk by maintaining a healthy lifestyle, managing chronic conditions, and seeing your doctor for regular check-ups.

Screening programmes

Regular health screenings for conditions like diabetes, thyroid disease, and certain cancers can help detect problems early. Ask your doctor which screenings are right for you based on your age and health history.

Complications

If left untreated

• Malnutrition – not getting enough nutrients.
• Weakened immune system – making you more prone to infections.
• Loss of muscle mass and strength (sarcopenia).
• Fatigue and decreased ability to do daily activities.
• Worsening of the underlying disease.

Long-term outlook

The outlook depends on the cause. Many conditions that lead to unexplained weight loss are treatable, and with proper medical care, most people can regain weight and feel better. Early diagnosis gives you the best chance for recovery.

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