Medically reviewed by:
Dr Dan Bunstone - Medical Officer
When to speak to a doctor about weight loss
Weight loss can be intentional, such as from dieting and exercise, or it can be a normal part of life, such as after a stressful event. However, sometimes it can be a symptom of an illness.
If you feel like you are losing weight for no reason, or are losing weight but eating more, then you should consider speaking to a doctor, as you may have an underlying condition.
You should speak to a doctor if you have lost more than 5% of your body weight over a 6 to 12-month period unintentionally, as it could be a sign that something is wrong.
Our doctors can help if you're experiencing unintentional weight loss. They will listen to your symptoms, and ask questions to find out more about what could be causing it. If you need to be referred to a specialist for further investigation, they can do this too.
Weight loss and other symptoms
There are certain other symptoms that you should look out for alongside weight loss. You should speak to a doctor if you also have:
- A loss of appetite
- Extreme, or persistent tiredness
- A change in your bowel movements
- You are getting ill regularly
- You are extremely thirsty
- You are urinating more frequently than normal
What can weight loss be a symptom of?
Unintentional weight loss could be due to an underlying condition such as:
An overactive thyroid gland (hyperthyroidism) can cause your body to make too much of a hormone called thyroxine. This results in many of the body’s functions speeding up. There are many symptoms that may accompany your weight loss, such as restlessness, irritability, anxiety, poor sleep, palpitations, increased sweating, shaking and diarrhoea.
With depression, you may eat less because of the way you are feeling, causing you to lose weight. In some cases, it is family or friends that may first notice that you have lost weight rather than yourself
In most cases of cancer, other symptoms will appear before weight loss. However, in some cases, weight loss is the first symptom. Unexplained weight loss caused by cancer is due to the increased activity of cancer cells, which require nutrition from the body.
One of the main signs of type one diabetes is weight loss, along with going to the toilet a lot, being thirsty, feeling tired and blurred vision. If you have any of these symptoms, you should see a GP for more advice and investigation.
Type 2 diabetes can also cause weight loss if left untreated. Other symptoms include increased thirst, tiredness, blurred vision and passing large amounts of wee.
Weight loss can be a symptom of an eating disorder such as bulimia or anorexia. If you think you, or someone you know is struggling with an eating disorder, you should seek help, either from a medical expert, or someone you trust, who can help you get the advice you may need.
Less commonly, you may also lose weight due to:
- Gastroenteritis - This bacterial or viral stomach bug causes vomiting and diarrhoea. Most cases in children are caused by rotavirus, while cases in adults are usually caused by norovirus.
- Addison’s disease - Also known as hypoadrenalism or primary insufficiency, this is a rare disorder of the adrenal glands, where your body does not produce enough aldosterone or cortisol. Other early symptoms include muscle weakness, a low mood, fatigue, increased thirst and a loss of appetite.
- Rheumatoid arthritis - This long-term condition causes swelling, pain and joint stiffness. Typically, symptoms affect the hands, wrists and feet and may occur in cycles of flare-ups. If you have rheumatoid arthritis you may experience weight loss, along with tiredness.
- Dysphagia - Swallowing problems can cause you to lose weight over time. It can also cause repeated chest infections.
- Inflammatory bowel disease (IBD) - IBD (Crohn’s disease or ulcerative colitis) are long-term conditions involving inflammation of the gut. If you have IBD you may also have symptoms of weight loss, extreme tiredness, bloody or recurring diarrhoea and stomach pain.
- Coeliac disease - This causes inflammation of the small intestine, making it unable to absorb nutrients. Symptoms include weight loss, bloating, diarrhoea and abdominal pain.
- Lupus - This is another long-term condition that causes inflammation in the skin, joints and organs. The main symptoms of lupus are weight loss, light sensitivity and swollen glands.
- Chronic infection/inflammation – Occasionally, weight loss is the first symptom that is noticed in infections such as Tuberculosis (TB) or HIV. It may also be the first thing that you notice if you have an inflammatory condition, such as polymyalgia rheumatica.
- Dementia - In the early stages of dementia, you may be happy within yourself and not realise that you are not looking after yourself properly. This may mean that you have a poor diet or miss meals. It may be family and friends that first notice your weight loss first.
- Alcohol or substance abuse - People who abuse alcohol or drugs may not look after themselves very well and this may cause them to have a poor diet, leading to weight loss.
This is not a conclusive list, speak to a GP about your weight loss for more advice.
What should you do if you are experiencing weight loss?
If you think you may have an underlying condition that’s causing your weight loss, it is a good idea to see a doctor.
At Push Doctor, you can see a GP online using any device, whether you are at home, work or on the go. The doctor will listen to your symptoms and ask questions during a face-to-face video consultation. They will diagnose the cause of your weight loss and suggest the right treatment to get you well as soon as possible.
You can talk to a GP about your weight loss at a time that suits you. Our doctors are available 7 days a week. They can also refer you to a specialist for further investigation or treatment if needed.