Unintentional weight loss

Some causes of unintentional weight loss

Weight loss is sometimes the first symptom noticed by the person, relative or friend. However, when carefully questioned by a medical professional, people may realise they have more symptoms in addition to their unintentional weight loss. Weight loss is usually defined as a loss of more than 5% of the person's body weight.

Common causes of unintentional weight loss are listed below. The list is not exhaustive.

Cancer

In the vast majority of cases of cancer, other symptoms will develop before any weight loss occurs. The first signs of cancer depend on the type and site of the cancer. However, occasionally, weight loss is the first symptom that is noticed. Common cancers that cause weight loss include those affecting the pancreas, the oesophagus, the stomach, the bowel and the lung. The blood cancer lymphoma, of which there are several types, can cause unintentional weight loss among other symptoms.

Diabetes

Both Type 1 and Type 2 diabetes can cause unintentional weight loss. As with all causes of unintentional weight loss, it is important to report this to your doctor, as early diagnosis is important.

Anxiety and depression

Anxiety and depression have many symptoms and unintentional weight loss can occur for multiple different reasons. People suffering with these symptoms may experience weight loss or weight gain, for example, some people may respond by comfort eating, whilst others may experience a reduced appetite. Smokers may find they respond by smoking more; nicotine can reduce your appetite, causing weight loss. Some people may resort to alcohol to combat anxiety and this may also be associated with weight loss. Loneliness is a common experience for older adults and can affect a person's mood. Weight loss affecting someone whose mental health is suffering may be the most obvious symptom to family and friends.

Alcohol dependence

Some people who drink a lot of alcohol may struggle to look after themselves well, which can cause them to lose weight. Family and friends may show concern about weight loss and not be aware that the person has an alcohol problem.

Hyperthyroidism

Hyperthyroidism occurs when the thyroid gland produces too much of a hormone called thyroxine. This condition is also known as an overactive thyroid. The extra thyroxine causes many of your body's functions to speed up. This often causes many symptoms affecting different parts of the body. In the early stages of hyperthyroidism some people actually feel well and full of energy and don't realise they have a problem despite their weight loss.

Persistent (chronic) infection or inflammation

It would be unusual not to have other symptoms with a chronic infection. But, occasionally, the first symptom that is noticed with infections such as tuberculosis or HIV is weight loss. Hookworm infection of the gut is another example where weight loss may be the first indication of disease. Hookworm is a very common problem worldwide (but rare in the UK). Likewise, there are various conditions that cause persistent inflammation of a part or parts of the body. Again, other symptoms would be usual. However, sometimes an inflammatory condition such as polymyalgia rheumatica may make you feel vaguely unwell and lose weight prior to other symptoms developing.

Malabsorption syndromes

There are various diseases that can affect the way food is absorbed and taken into the body from the gut. These would normally cause gut symptoms such as diarrhoea and abdominal pain. However, weight loss may be the first symptom noticed. Examples include coeliac disease, Crohn's disease and ulcerative colitis.

Dementia

People with dementia may struggle to look after themselves well and lose weight as a result. There can be many reasons for this. In older adults, weight loss may sometimes be the first symptom friends or family notice.

Eating disorders

In conditions such as anorexia, a person usually knows they are tightly controlling their diet and exercise and are actively trying to lose weight. However, this may be very carefully hidden from friends and family and may not be divulged even to the doctor.

Side-effects from medication

Sometimes medication may cause side-effects resulting in weight loss. For example, some medicines may cause a loss of appetite, or a dry mouth. Some cause heartburn or give a mild tummy discomfort. Others may affect the sense of taste or smell, or make people feel sick. Any of these side-effects could affect eating habits and result in weight loss.

Other common causes

There are many reasons a person can lose weight unintentionally, and they are not all because of specific health conditions. Common issues such as lack of money, lack of access to food, difficulty buying and cooking food or difficulty eating can all cause unintentional weight loss. At each of these stages there are many, wide ranging causes which can result in unintentional weight loss. For example difficulty eating can be due to having a problem in your mouth or any condition affecting your ability to accurately place food in your mouth.

If you keep losing weight for no reason, see a doctor. This is because, as a general rule, the earlier a serious problem is diagnosed, the better the chance that treatment may improve the outlook (prognosis).

Your doctor is likely to ask various questions. He or she may actually uncover other symptoms that you were either unaware of or did not think were significant. He or she may also examine you. Tests, such as blood tests, may or may not be appropriate. Following a doctor's assessment, the likely cause may be clear or you may require more investigations. Your doctor will advise on what is needed depending on what they think is causing the weight loss.

The treatment depends on the cause. See individual leaflets on the various diseases that can cause weight loss. The conditions above are not an exhaustive list.