The Benefits of Fasting for Autoimmune Conditions and Bowel Health.
NB- discuss your plans with your physician before embarking on this lifestyle.
In recent years, fasting has gained attention not just as a weight-management tool, but as a therapeutic approach for health restoration. Emerging research suggests that fasting may help regulate immune function, reduce inflammation, and even improve gut health – making it a powerful option for people living with autoimmune conditions and digestive challenges.
🧬 How Fasting Impacts the Immune System
Autoimmune conditions, such as rheumatoid arthritis, multiple sclerosis, and inflammatory bowel disease (IBD), occur when the immune system mistakenly attacks the body’s own tissues. A key feature is chronic inflammation, which drives symptoms and tissue damage.
Fasting influences the immune system in several ways:
Reduced Inflammation: Studies show intermittent fasting and longer fasting periods lower pro-inflammatory cytokines such as IL-6 and TNF-α, which are commonly elevated in autoimmune disease (Longo & Mattson, 2014).
Immune Cell Renewal: Periods of fasting stimulate the body to recycle old or damaged immune cells through a process called autophagy, followed by the production of new immune cells once feeding resumes (Cheng et al., 2014).
Improved Immune Regulation: By balancing T-cell populations, fasting may reduce overactivity of immune responses while preserving infection-fighting capacity.
🌱 Fasting and Gut Health
The bowel is central to autoimmune health. Around 70% of our immune system resides in the gut, and disruptions in the gut microbiome are strongly linked to both autoimmunity and bowel conditions.
Fasting supports bowel health by:
Promoting Microbiome Diversity: Time-restricted eating has been shown to encourage beneficial bacteria and restore microbial balance (Chaix et al., 2019).
Allowing Gut Rest and Repair: Digesting food takes a huge amount of energy. Fasting periods allow the gut lining to heal, which is particularly helpful in “leaky gut” associated with autoimmune flares.
Enhancing Motility and Clearing Debris: Fasting activates the migrating motor complex (MMC), a cleansing wave of muscular contractions that helps move undigested material and bacteria out of the small intestine.
🔬 The Science So Far
Fasting-Mimicking Diet (FMD): Research led by Dr. Valter Longo has shown that cycles of a plant-based, calorie-restricted fasting-mimicking diet reduced autoimmunity and promoted regeneration of pancreatic and immune cells in animal models (Cheng et al., 2014).
Rheumatoid Arthritis: Clinical trials have found that short-term fasting followed by a vegetarian diet improved joint pain and inflammation in people with rheumatoid arthritis (Müller et al., 2001).
IBD and Gut Inflammation: Early studies suggest that intermittent fasting reduces inflammatory markers in bowel conditions and may protect against colitis by reshaping gut bacteria (Rangan et al., 2019).
While research is still developing, these findings highlight fasting’s potential as a complementary strategy in managing autoimmune and bowel-related conditions.
💡 Top Tips for Safe Fasting
Fasting can be powerful, but it’s not one-size-fits-all. If you’re considering fasting for autoimmune or gut health, here are some practical guidelines:
Start Gently – Begin with a 12–14 hour overnight fast and gradually increase to 16 hours if tolerated.
Stay Hydrated – Water, herbal teas, and black coffee/tea (without sugar) can help keep you comfortable.
Prioritise Nutrient-Dense Foods – When eating, focus on anti-inflammatory foods such as leafy greens, oily fish, olive oil, and fermented foods to support gut bacteria.
Consider Fasting-Mimicking Approaches – A structured 5-day low-calorie fasting-mimicking diet may provide benefits without complete abstinence.
Listen to Your Body – Fasting isn’t suitable for everyone, especially those who are underweight, pregnant, have eating disorders, or certain medical conditions. Always seek medical advice before making significant changes.
Pair with Gut-Supporting Practices – Mindful eating, reducing ultra-processed foods, and incorporating probiotics can amplify the benefits.
✨ Final Thoughts
Fasting isn’t a cure, but it may be a valuable tool for calming the immune system and supporting bowel health. Combined with other lifestyle practices—like stress reduction, sleep optimisation, and movement—it offers a holistic way to manage symptoms and restore vitality.
References
Cheng CW, et al. (2014). Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression. Cell Stem Cell, 14(6), 810–823.
Longo VD & Mattson MP. (2014). Fasting: Molecular mechanisms and clinical applications. Cell Metabolism, 19(2), 181–192.
Müller H, et al. (2001). Fasting followed by vegetarian diet in patients with rheumatoid arthritis: a review. Scand J Rheumatol, 30(1), 1–10.
Chaix A, et al. (2019). Time-restricted feeding prevents obesity and metabolic syndrome in mice lacking a circadian clock. Cell Metabolism, 29(2), 303–319.
Rangan P, et al. (2019). Fasting-mimicking diet modulates microbiota and promotes intestinal regeneration to reduce inflammatory bowel disease pathology. Cell Reports, 26(10), 2704–2719.
⏱️ How Long Do Fasts Need to Be?
12–16 hours (Intermittent fasting / time-restricted eating)
Most common and safest starting point.
Gives the gut a rest, improves insulin sensitivity, activates the migrating motor complex (clearing the gut), and may support microbiome diversity.
Benefits for bowel health and low-level inflammation start here.
24 hours (Occasional extended fast)
Usually done once or twice a week.
Deeper autophagy (cellular clean-up) begins.
Can improve inflammatory markers and reduce immune overactivity, helpful in some autoimmune conditions.
48–72 hours (Prolonged fast)
Triggers stem cell regeneration and more profound immune system “reset” (Cheng et al., 2014).
Has been studied in autoimmune diseases and shown to reduce disease activity in models.
Not necessary for everyone, but can be used a few times a year under guidance.
Fasting-Mimicking Diet (FMD, 5 days)
Developed by Dr. Valter Longo. Plant-based, low-protein, calorie-restricted.
Provides benefits similar to prolonged fast without complete food abstinence.
Studied for autoimmune diseases and inflammatory bowel conditions with promising results.
📆 How Regularly?
Daily gut reset: 12–16 hour overnight fast (e.g. finish eating at 7 pm, eat breakfast at 11 am).
Weekly immune support: One 24-hour fast, or two non-consecutive “light days” (sometimes called 5:2 fasting).
Occasional deep reset: 48–72 hours, or a 5-day fasting-mimicking diet, done every 2–3 months under professional supervision.
⚖️ Important Considerations
Consistency matters more than intensity — a regular 14–16 hour fast is often more sustainable than long fasts.
Women with autoimmune conditions may find 14 hours daily + occasional longer fasts works best (too much fasting can affect hormones).
Anyone with IBD flares, low body weight, diabetes, or on medication should consult a doctor before extended fasts.
✨ So in practice:
For bowel health → daily 14–16 hours is enough.
For immune “reset” in autoimmunity → add in occasional 48–72 hours or FMD cycles a few times per year.