Fasting is safe for the vast majority of healthy adults. But there are a few exceptions.
In some situations, fasting is not recommended or requires medical approval beforehand. Sometimes Extended Fasting (EF) is not optimal but intermittent fasting (IF) works great.
If you have any specific health conditions or concerns, you should always consult your doctor or another qualified healthcare professional before fasting and before taking fasting supplements.
Please be extra-cautious if any of the following apply to you.
Fasting while pregnant or breastfeeding
You should NOT fast if you are pregnant or breastfeeding.
Your baby needs lots of nutrients to grow. Shortage of nutrients during this stage would harm both you and your baby.
This is recognised by traditional religions that incorporate fasting. For example, pregnant Muslim women don’t have to fast during Ramadan.
Fasting while trying to conceive
There is anecdotal evidence that fasting helps with reproductive health. For overweight people, reducing their weight improves fertility. But it’s better to do this well in advance.
Once you are actively trying to conceive, stop fasting or dieting and focus on getting plenty of nutrients.
Fasting and low BMI / low fat percentage
BMI below 18 is considered underweight. Fat percentage of lower than 10% for women and 5% for men is also below healthy weight. Anyone in this weight bracket should NOT fast.
Healthy fasting uses up your fat stores. It works best for people who are overweight or close to overweight.
Fasting without sufficient fat reserves will lead to malnutrition. Negative impact on your health will far outweigh any potential positives.
Fasting and high blood pressure
Fasting reduces blood pressure. But fasting electrolyte supplements can temporarily raise it, especially sodium.
Intermittent fasting (IF) is safer for people with high blood pressure than extended fasting (EF). You can do intermittent fasting without supplements.
But you will need to take electrolytes during EF. As supplements are more concentrated than food, they may cause a potentially dangerous spike in BP if it’s already quite high.
Always consult your doctor before fasting and before taking any electrolyte supplements. If you decide to go ahead, make sure to monitor your blood pressure regularly.
Fasting and kidney health
Fasting depletes electrolytes. Electrolytes are bound with water in our body tissues.
Electrolytes get depleted rapidly during fasting leading to dehydration. Electrolyte supplements can help but they are more concentrated than foods and therefore cause greater fluid fluctuations.
Your kidneys play a key role in maintaining the optimal water balance in your body.
If you have any kidney-related conditions or health issues, always consult your doctor before fasting and before taking any electrolyte supplements.
Fasting and prescription medications
Fasting and electrolyte supplements can interfere with certain prescription medications. Fasting is still quite niche so it might not be mentioned on your medication leaflet.
Always consult your doctor or pharmacist to check whether it’s safe for you to fast and to take supplements.
Fasting and eating disorders
Fasting is potentially dangerous for anyone who has a past history of eating disorders, especially anorexia. Please discuss your plans with a qualified mental health professional first to ensure it’s safe for you to fast.
Fasting and family history of famine
Controlled voluntary fasting is practiced widely for weight loss and health reasons, and as part of religious traditions. Unfortunately, in some areas of the world people can suffer from involuntary food deprivation due to poverty or natural disasters.
If you or anyone in your immediate family experienced a severe food shortage or a famine, this will have a long-lasting psychological effect. Trying to fast may trigger a trauma response in your body and mind. So it might not be the optimal choice for you.
Fasting for children
Extended fasting is not recommended for children. Intermittent fasting may help if there are severe issues such as morbid obesity and if approved by a doctor.
Fasting for anyone under 18 years old should be supervised by a parent or a medical professional to ensure that all fasting safety guidelines are followed.
How to fast safely
- Drink plenty of water
- Get enough sleep
- Try to limit your exposure to stress
- Stop your fast if you feel really unwell
- If you have any medical conditions or health concerns, consult your doctor before fasting
Additional for Extended Fasting (EF)
- Take electrolyte supplements
- Plan a gentle and controlled refeed phase
