Having a healthy appetite is an essential part of life – it increases our desire to eat and allows us to get the right amount of nutrients we need to stay healthy.
So, how does our appetite work? When we’re hungry, the body recognises our need for food and sends a signal – like a rumbling stomach – to the brain to eat. Hormones play a key role in regulating your body’s appetite. Ghrelin, the ‘hunger hormone’, stimulates your appetite, and leptin tells your brain when you’ve eaten enough.
‘Many factors can affect the regulation of these hormones and can interfere with our appetite drive,’ explains Dr Rhianna McClymont, Lead GP at Livi. Most of us experience loss of appetite at one point or another – whether it’s because of environmental factors, medication or psychological or physical conditions.
What causes loss of appetite?
In most cases, a decreased appetite is only short term, but if it’s longer lasting you may need treatment for an underlying problem. Here are some of the key causes:
1. A viral or bacterial infection
‘Viral and bacterial infections – including flu-like illnesses, tummy bugs and urine infections – are a common reason for appetite loss,’ says Dr McClymont.
‘When you’re unwell, the body releases chemicals called cytokines, which regulate appetite as part of an inflammatory and immune response that act on neurons in the brain. This suppresses our appetite drive, making us less keen to eat.’
2. A long-term health condition
Certain long-lasting medical conditions can affect our appetite in different ways. Some conditions that may cause a lack of appetite include:
Migraines, fibromyalgia and arthritis can cause you to lose interest in food.
People with poorly controlled diabetes may lose their appetite due to a condition called gastroparesis, where food moves too slowly through the digestive tract due to damaged nerves.
‘Conditions that affect the gut, such as inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS), can affect our appetite through symptoms that make us less inclined to eat – including abdominal pain, bloating, diarrhoea and gut spasms,’ explains Dr McClymont.
As we age, our appetite changes. It’s estimated that up to 30% of older people experience a reduction in appetite and eat less food, leading to weight loss and nutritional deficiencies. One study found that older people have higher levels of the hormone peptide YY, which makes them feel full.
You can also experience a reduced appetite as a result of illnesses like Alzheimer’s and Parkinson’s disease or other conditions, including dental and swallowing problems. Lack of exercise, feeling lonely or socially isolated or an inability to prepare meals can also cause a reduced appetite.
4. Psychological factors
Mental health conditions can have a significant impact on your appetite. People experiencing depression often lose interest in food, and our appetite tends to decrease when we’re feeling anxious or stressed or as a consequence of life events like a relationship break-up or the death of a loved one.
‘During stressful events, your brain releases the “fight-or-flight” hormone, adrenaline, which slows down your digestive system,’ says Dr McClymont. ‘Depression triggers the production of corticotropin-releasing hormone, which also curbs your appetite.’
Certain medicines can cause a decreased appetite as a side effect, including opioid painkillers, antidepressants, antibiotics, medication for type 2 diabetes.
Cancer treatments can also cause appetite loss, with around 60% of people diagnosed with cancer experience a loss of appetite. Treatments such as chemotherapy and immunotherapy can cause taste changes and symptoms such as nausea, which is a common side-effect of chemotherapy, can aggravate this further.
‘If you feel one of your medications is causing a change to your appetite, it’s always best to raise this with a doctor. There may be a suitable alternative you can try,’ advises Dr McClymont.
6. An underactive thyroid
If you have an underactive thyroid, also known as hypothyroidism, your thyroid gland is not producing enough hormones. This causes many of the body’s functions to slow down, which can result in a loss of appetite. Other symptoms include weight gain, tiredness and depression.
If a doctor thinks you have an underactive thyroid, they can check the level of thyroid hormones in your body by doing a blood test.
7. Anorexia nervosa
‘Anorexia nervosa is an eating disorder and serious mental health condition characterised by a desire to keep your body weight as low as possible by restricting food intake, over-exercising or both,’ says Dr McClymont. This condition can also lead to a reduction in appetite.
‘People who suffer from this often have a distorted and negative body image. It requires specialist medical treatment and can be life-threatening in severe cases.’
8. Alcohol dependence
Drinking too much alcohol has numerous physical signs, including having a sore or upset stomach, a yellow skin tone and feeling numbness and tingling in your feet and hands. It can also have a big impact on appetite – and you may lose all interest in food as your focus shifts to alcohol.
If you’re finding moderating alcohol difficult, speak to a doctor who can recommend further support.
Are there other symptoms that can impact appetite loss?
Although losing your appetite and skipping meals has many different causes, it may also be a direct result of other symptoms, including:
1. Loss of taste
Covid-19 affects our appetite in the same way as other viruses – but one of its main symptoms, the loss of smell or taste, can also affect our appetite. One study found that 87% of respondents who experienced a loss of smell or taste from Covid-19 experienced a reduced enjoyment of food.
‘Pregnancy is a common cause of appetite loss, primarily due to nausea,’ explains Dr McClymont. ‘The term “morning sickness” can occur any time of day and is particularly common in the first trimester.
‘Hyperemesis gravidarum is an extreme form of pregnancy nausea and vomiting, which can lead to dehydration and weight loss. If this is affecting you, it’s important to discuss it with a doctor or midwife because it generally needs treatment with anti-sickness medications and may require hospital admission for fluid rehydration.’
If you’re experiencing fatigue as a result of another condition, it may make you feel less inclined to cook or eat food. ‘Loss of appetite and tiredness are symptoms of other conditions. Often, a loss of appetite will naturally lower your energy reserves, leading to tiredness,’ says Dr McClymont.
When should I speak to a doctor?
Appetite loss can have a broad range of causes, but it’s important to speak to a doctor if you notice any other symptoms alongside a loss of appetite, including:
- Stomach pain
- A change to your normal bowel pattern
- Problems swallowing
- Unintentional weight loss
- New indigestion
‘If you experience appetite loss that’s persistent and doesn’t seem to be related to a simple explanation, such as a cold or flu virus, speak to a doctor,’ says Dr McClymont.
This article has been medically approved by Dr Rhianna McClymont, Lead GP at Livi