Fasting and Immune Health
posted 31st March 2026
The definition of fasting means taking in no calories for a set period. This may be for a few hours each day or sometimes for entire days. People fast for a variety of reasons. For example, sometimes it is for religious practice whereas alternatively it could be for health benefits.
Who Can Participate in Fasting
It is important to note that fasting may not be suitable for everyone due to some pre-existing conditions. If you are pregnant or breastfeeding, have Type 1 Diabetes or a history of or at risk of eating disorders, then you should not try any form of fasting. If you are an older adult and on any form of medication you should also check with a medical professional as fasting may also not be suitable for you.
Different Fasting Therapies
Broadly speaking, there are three main types of fasting therapy to consider:
- Intermittent Fasting - This is a general term used to describe cycling between periods of restricting calorie intake and periods of not restricting calorie intake.
- Time-Restricted Eating (TRE) - Only consuming calories during a set window of time.
- Prolonged Nightly-Fasting - Lengthening the time of a typical overnight fast.
Some people fast for several days at a time but there is not good evidence that long fasts benefit your health or support long term weight loss. They also come with potential health risks.
General Health Benefits
Research shows that fasting is linked to the following health benefits:
- Improvements in a range of health areas such as cardiovascular and metabolic health, type 2 diabetes, weight management and improved brain function
- Reduction in inflammation and oxidative stress measurements, two processes which can damage the cells in our body.
- An increase in autophagy, the beneficial “housecleaning” process where both damaged cells and pathogens are removed from our bodies.
- Supports mitochondrial health, the energy batteries within our cells.
A recent research study compared inflammatory biomarkers between participants in a normal diet control group and a time-restricted eating (TRE) intervention group. After 12 months, the TRE participants showed a reduction in inflammatory measurements whilst insulin sensitivity and cholesterol markers were significantly improved when compared to the normal diet group.
The Gut-Immune Fasting Relationship
Much of the body’s immune response is connected to the gut microbiome and the influence of nutrition and fasting on this complex bi-directional gut-immune relationship continues to be discovered. For example, several research studies have found that fasting impacts gut-immune health via a reduction in inflammation in the gut lining and an increase in protective gut bacteria in the microbiome. Some fasting protocols have demonstrated a boost in beneficial gut bacteria populations with an increase in health promoting metabolites which support immune function.
Summary
So as you can see, it is not only what you eat that is beneficial for overall health but when you eat can be equally important! Working with a nutritional therapist can be helpful in identifying an appropriate fasting strategy that is personalised to the individual and advise on ways to start building this into your daily routine.
If you would like to book a free discovery call to see how Nutritional Therapy can help you, please contact Medicinal Eating or email direct at info@medicinaleating.co.uk.*
