Fasting-Mimicking Diet Shows Promise for Autoimmune Diseases

Emerging research suggests that a fasting-mimicking diet (FMD) may offer significant benefits for individuals with autoimmune diseases like Crohn’s disease and ulcerative colitis. While traditional fasting has shown some promise, the FMD provides a safer and potentially more effective approach to harnessing the regenerative power of fasting.

The Science Behind Fasting and Autoimmunity

Valter Longo, PhD, a professor of gerontology and biological sciences at the University of Southern California and director of the USC Longevity Institute, has been a leading researcher in this field. His work initially focused on the role of fasting and nutrient response genes in aging and disease. USC Leonard Davis School of Gerontology

Early studies in animal models demonstrated that fasting cycles could stimulate stem cell activation and promote regeneration of the immune system. This sparked interest in exploring the potential of fasting-based interventions for autoimmune conditions.

A Patient’s Story and Initial Observations

In 2015, Dr. Longo received an email from a journalist, Jenni Russell, who had been suffering from intestinal autoimmunity for 20 years. Her symptoms had worsened after chemotherapy, and she relied on immunosuppressant drugs to manage her condition. Despite the lack of human studies, Russell, exhausted from her condition, decided to try cycles of fasting.

After four cycles of a 3-4 day fasting regimen, Russell was able to discontinue her immunosuppressant medications, and her autoimmune symptoms subsided. This anecdotal evidence prompted further investigation into the effects of fasting on autoimmune diseases.

Fasting-Mimicking Diet vs. Water Fasting

Subsequent research by Dr. Longo and his team revealed that while water fasting offered some benefits, the fasting-mimicking diet had broader effects. The FMD involves consuming foods high in unsaturated fats but low in calories, protein, and carbohydrates for a specific period, mimicking the effects of a water-only fast while providing essential nutrients. The inclusion of prebiotics in the FMD also appeared to positively influence the gut microbiota.

Clinical Trial Results

Recent clinical trials have provided more robust evidence supporting the potential of FMD for autoimmune diseases:

• Ulcerative Colitis: A 2025 study at the University of Miami, involving 32 patients with ulcerative colitis, showed that two cycles of FMD, combined with medication, led to significant improvement in 57% of patients, compared to 35% in the group treated with medication alone.
• Crohn’s Disease: A study at Stanford University, published in Nature Medicine, involving nearly 100 patients with Crohn’s disease, found that 64% of patients who received both medication and FMD achieved clinical remission, compared to 37% in the medication-only group.

These trials demonstrated a significant reduction in inflammation, as evidenced by a decrease in stool calprotectin levels – a marker of intestinal inflammation – in patients following the FMD.

Important Considerations and Future Research

While the results are promising, it’s crucial to note that the effects of FMD may be temporary if the underlying causes of inflammation are not addressed. For example, individuals with celiac disease must continue to avoid gluten even while following an FMD.

Dr. Longo emphasizes the need for standardization and regulation of the FMD, similar to pharmaceutical drugs. Larger clinical studies are also needed to confirm these findings and explore the potential of FMD for other autoimmune diseases.

Key Takeaways

• The fasting-mimicking diet shows promise as a complementary therapy for autoimmune diseases like Crohn’s disease and ulcerative colitis.
• FMD may promote immune system regeneration and reduce inflammation.
• Clinical trials have demonstrated significant improvements in patients with ulcerative colitis and Crohn’s disease.
• The effects of FMD may be temporary if underlying causes of inflammation are not addressed.
• Further research is needed to standardize and regulate FMD and explore its potential for other autoimmune conditions.