Fasting means choosing to refrain from eating or drinking, or both, for a certain period of time.
Some people may wish to fast for personal, cultural or religious reasons. One of the most common religious reasons is Ramadan. During this 30-day period, Muslims fast from dawn until sunset.
Is it safe to fast after having a stroke?
This page can only give general information. For individual advice on your health and treatment, always consult a healthcare professional, such as a GP or pharmacist.
It is important to speak to a healthcare professional who understands your medical history before deciding to fast. Where possible, have this conversation several weeks before your fast begins.
There is limited research looking at the safety of fasting in people who have had a stroke. Stroke is different for everyone. Some people may be able to fast safely, while fasting may carry greater risks for others.
Your individual risk will depend on factors such as:
- How recently you had your stroke.
- Your recovery.
- Whether you have difficulty swallowing, eating or drinking, or are at risk of malnutrition.
- Whether you are frail or at risk of falls.
- Your other health conditions.
- The medicines you take.
- Whether you can drink enough between fasting periods.
- Whether you can recognise and respond to signs of dehydration and low blood sugar or symptoms, such as dizziness.
Muslims are not required to fast if they are ill or if their medical condition could get worse by fasting. This may include some stroke survivors, who may then honour Ramadan in different ways.
Medication
Many medications need to be taken at certain times of the day, or at regular intervals. Others need to be taken before or with food. This can make it difficult to take medication as prescribed while fasting.
But changing your medication schedule is not always safe. Many conditions can be negatively affected if medication is not taken as prescribed.
You should speak with your pharmacist, GP or stroke specialist about whether it is safe to change your medication schedule before beginning a fast. They may be able to help you adapt your medication. Or they may advise against doing so.
Dehydration
Dehydration is when you do not drink enough fluids to replace the ones you lose through breathing, sweating, going to the toilet and so on. It can be serious if it isn’t treated.
The NHS has information on the symptoms of dehydration and how to avoid it.
Fasting for any period can increase the risk of dehydration, particularly during hot days, while exercising, or if you already find it difficult to drink enough.
Dehydration reduces the amount of fluid circulating in the body and makes the blood thicker. This may increase the risk of low blood pressure, kidney problems and blood clots, particularly if you are unwell or have mobility problems.
If you’re dehydrated, some medicines, including diuretics and certain medications for blood pressure, heart failure, diabetes or kidney disease, can increase the effects of dehydration or risk of kidney problems. Do not stop these medicines without speaking to a pharmacist or doctor.
Research has found an association between dehydration and stroke. However, this does not prove that dehydration directly causes a stroke, or that dehydration will lead to another stroke.
Research also suggests dehydration at the time of a stroke, or soon afterwards, is linked to poorer outcomes.
It may not be safe for you to continue fasting if you cannot stay hydrated. Drinking enough of the right kinds of fluid before and after your fast is essential.
Swallowing and nutrition
A stroke can make it difficult to swallow, drink enough, prepare food or feed yourself. Some people also have a reduced appetite or awareness of thirst.
Fasting may be unsafe if you:
- Have difficulty swallowing.
- Cough or choke when eating or drinking.
- Need thickened drinks or modified-texture foods.
- Receive food, fluids or medicines through a feeding tube.
- Cannot eat or drink enough between fasting periods.
- Have recently lost weight or are at risk of malnutrition.
Speak to your stroke team, speech and language therapist or dietitian before fasting. Continue to follow any advice you may have been given about safe food and drink textures.
Specific medical conditions
There are some medical conditions that need extra consideration when deciding whether to fast. This is not a complete list.
Some people find it difficult to manage their diabetes during a fast.
Fasting can increase the risk of blood sugar becoming too low (hypoglycaemia) or too high (hyperglycaemia). High blood sugar can increase the risk of dehydration and, in some cases, diabetic ketoacidosis (a serious condition requiring hospital treatment).
You should always speak with your GP or specialist team before the start of your fast.
There are a few things they will need to consider, including:
- Whether you have type 1 or type 2 diabetes.
- If you are able to keep your blood sugar in a healthy range.
- Whether you have had severe or frequent hypoglycaemia, and can recognise the symptoms of hypoglycaemia.
- Whether you use insulin or medicines that can cause hypoglycaemia.
- The type of medication you use to manage your diabetes and if tablets need to be taken at specific times.
- Whether you have kidney disease or other complications.
- Whether you can monitor your blood sugar level regularly.
Speak to your healthcare team before fasting and do not make any changes to your medication without their advice. They can assess your risk and help you make a plan.
Diabetes UK has more information on fasting with diabetes.
Changes to sleep and eating routines during fasting may affect how some people with atrial fibrillation (AF) feel or make medicines harder to take at the correct times.
Blood-thinning medications, need to be taken exactly as prescribed to help protect you from stroke. Do not change the timing without speaking to a pharmacist or GP.
If you take warfarin, changes in your diet, mealtimes or fluid intake may affect how quickly your blood clots. Your healthcare team may suggest additional monitoring during or after fasting to make sure your warfarin dose is still right for you.
If you have AF, you should speak with your pharmacist, GP or specialist before starting a fast.
Fasting may lead to a reduction in blood pressure, but people respond differently. Blood pressure may fall too low if you become dehydrated or take certain medicines, which can cause dizziness, faintness or falls.
In contrast, missing tablets may lead to an increase in blood pressure or it becoming less well controlled.
As with any chronic medical condition, you should speak with your GP or specialist before fasting.
Do not change your medicines without speaking to a healthcare professional. Your healthcare professional may recommend checking your blood pressure during the fasting period, particularly if you have symptoms or your treatment has recently changed.
Can I still exercise or do my physiotherapy?
Physical activity and rehabilitation remain important after a stroke. Many people can continue exercising while fasting, but the timing, duration or intensity may need to change.
If you sweat too much during your exercise, you could become dehydrated. That is why many people switch to gentler exercises like walking and yoga if they are fasting.
Stop exercising if you feel unwell, dizzy or unsteady.
If you are undertaking regular physiotherapy, you should speak with your physiotherapist before fasting. Your therapist may adjust the timing or intensity of your sessions, depending on how strenuous they are.
Planning for a fast
If you and your healthcare professional agree that you can fast, plan how you will eat, drink and take medicines between fasting periods. It may be useful to involve a friend, family member or carer in this plan.
Before fasting, make sure you know:
- When and how to take each medicine.
- How much fluid you should drink.
- Whether you need to monitor your blood pressure, blood sugar levels or how quickly your blood clots.
- Which symptoms mean you should break your fast.
- Who to contact if you become unwell.
Tips for healthy eating during Ramadan
If you are fasting during Ramadan, it is important that you choose the right foods and drinks both before (suhoor) and after (iftar) you fast.
Suhoor
- Try not to miss the pre-dawn meal. Include foods that provide useful nutrients and energy that is released slowly over several hours, such as:
- Oats or wholegrain bread.
- Bulgur wheat, brown rice or other wholegrains.
- Lean protein.
- Beans, lentils or chickpeas.
- Fruit and vegetables.
- Nuts and seeds.
- Stay hydrated using plenty of sugar-free drinks. If you don't like water, try adding a little sugar-free squash.
- Avoid salt and salty foods. These can make you more dehydrated and are not good for your blood pressure.
- Try baking or grilling your food instead of frying it.
- Limit fatty and sugary foods.
Iftar
- Break the fast gradually and avoid very large meals. Include vegetables, wholegrains and a source of protein.
- Limit foods and drinks that are high in free sugars, particularly if you have diabetes.
- Drink regularly between iftar and suhoor rather than trying to drink a large amount all at once.
- Avoid drinking excessive amounts of caffeinated drinks, which can affect sleep and may increase urine production leading to dehydration.
It may be beneficial to take a daily multivitamin and vitamin D during Ramadan because you may not consistently get all your essential vitamins and minerals from diet alone. Please speak to your dietitian or GP first for advice on taking multivitamins and vitamin D during Ramadan, alongside other medication.
The British Dietetic Association has more detailed information on healthy eating during Ramadan.
When should I break my fast?
You should break your fast and seek medical advice if you develop signs that you may be becoming unwell, including:
- Dizziness or feeling faint.
- Confusion, unusual drowsiness or severe weakness.
- Repeated falls or being unable to stand or walk safely.
- Very dark urine or passing much less urine than usual.
- Vomiting or diarrhoea.
- Symptoms of very low or very high blood sugar.
- Palpitations with chest pain, breathlessness or fainting.
Call 999 immediately if you develop any symptoms of stroke, even if the symptoms improve or this means breaking your fast.
Acknowledgements
Thanks to Dr Sundhya Raman, Lifestyle Medicine Lead at the Primary Care Cardiovascular Society, and Konstantinos Eleftheriadis, Specialist Stroke Dietitian and Medical Lead at the North Middlesex University Hospital NHS Trust, for their help with reviewing this information.