Reducing inflammation is one of the most frequently repeated claims about intermittent fasting. Fasting and weight loss can influence some inflammatory markers, and researchers are studying fasting in several autoimmune and inflammatory conditions. But much of the research is in animals or small, short human studies, and popular claims go well beyond what has been shown.
This page summarizes how fasting might affect inflammation, what research exists for specific conditions (rheumatoid arthritis, psoriasis, multiple sclerosis, IBD, and Hashimoto’s), and important safety points. It is educational only. Fasting is not a treatment for autoimmune disease; if you have one of these conditions, talk to your specialist before changing how you eat.
Table of Contents
How Fasting Might Affect Inflammation
Researchers have proposed several ways fasting could influence inflammation. Most are supported by laboratory or animal research, with less consistent evidence in people:
- Inflammatory markers. Some human studies have found reductions in markers such as C-reactive protein (CRP) and certain cytokines with intermittent fasting, while others have found little change. Where reductions occur, they often accompany weight loss.
- Less body fat. Excess fat, particularly around the abdomen, is associated with low-grade inflammation. Losing excess weight by any method tends to lower inflammatory markers.
- Ketones. Laboratory studies suggest the ketone beta-hydroxybutyrate can dampen an inflammatory pathway called the NLRP3 inflammasome. How relevant this is at the ketone levels reached during typical daily fasting is unclear.
- Autophagy. Fasting stimulates autophagy, a cellular recycling process, in animal studies. It is difficult to measure in humans, and its role in human inflammatory disease is not established. See autophagy and fasting.
- Microbiome. Fasting may shift gut bacteria, but links to inflammation in people are still being studied.
- Blood sugar. Improved blood sugar control, which can follow weight loss, is associated with lower oxidative stress.
These are plausible mechanisms, not proven effects. Whether they translate into meaningful benefit for specific conditions varies and is often unknown.
Rheumatoid Arthritis
Rheumatoid arthritis (RA) has the longest research history with fasting. Small clinical trials have found that a short, supervised fast followed by a vegetarian diet improved symptoms such as joint pain and stiffness in some participants. When people return to their previous diet after fasting alone, symptoms tend to come back.
Example study: Controlled trial of fasting and one-year vegetarian diet in rheumatoid arthritis. The Lancet (1991).
Important context:
- The fasts studied were short, extended fasts carried out under medical supervision, not everyday intermittent fasting
- Studies were small, and participants continued their usual RA treatment
- Evidence for daily time-restricted eating in RA is very limited
Extended fasting is not something to try on your own with RA, particularly if you take medications such as corticosteroids or methotrexate. Talk to your rheumatologist.
Psoriasis
Research is limited. Some small studies, including observational studies of people fasting during Ramadan, have reported modest improvements in psoriasis severity scores, while others have found no clear effect.
- Psoriasis is associated with obesity and metabolic syndrome, and weight loss in people with overweight has been linked with improvement in some studies
- It is unclear whether fasting has any effect beyond what weight loss provides
- Evidence for psoriatic arthritis specifically is sparse
Fasting should not replace prescribed treatment. Discuss any dietary change with your dermatologist or rheumatologist.
Multiple Sclerosis
There is research interest in fasting and related diets for multiple sclerosis (MS). What is available so far:
- In animal models of MS, fasting and fasting-mimicking diets have reduced disease signs
- Small human pilot studies have explored intermittent fasting and fasting-mimicking diets, mainly looking at safety, feasibility, and some symptom and quality-of-life measures
- There is no evidence yet that fasting changes the long-term course of MS in people
Fasting is not a recommended MS treatment. People with MS considering fasting should discuss it with their neurologist, especially alongside disease-modifying therapy, and be aware that fatigue and heat sensitivity can make fasting harder.
IBD (Crohn’s, Ulcerative Colitis)
The picture is mixed and research in people is limited. Some people in remission tolerate a daily eating window well; others find changes in meal pattern worsen symptoms.
- Fasting during active flares is generally not appropriate, as nutritional needs are often higher
- Many people with IBD are at risk of weight loss and nutrient deficiencies, which fasting can worsen
- Studies of fasting-mimicking diets in IBD are mostly in animals
- Eating enough during the eating window matters even more than for the general population
This is a decision to make with your gastroenterologist. See our gut health guide.
Hashimoto’s
There is little research on intermittent fasting in Hashimoto’s thyroiditis, and no good evidence that fasting changes the underlying autoimmune process or thyroid antibody levels. People on thyroid hormone replacement who choose to fast need to keep taking their medication consistently, usually on an empty stomach and separated from food as directed. See our thyroid guide and discuss timing with your doctor or pharmacist.
General Autoimmune Considerations
Common principles across autoimmune and inflammatory conditions:
- Don’t replace or change medication because of fasting. Any medication change must be made by your doctor.
- Don’t fast through active flares. Illness can increase energy and nutrient needs.
- Check your medications. Some, such as corticosteroids, certain pain relievers, and drugs that affect blood sugar, may need to be taken with food or may interact with fasting. See fasting and medications.
- Track symptoms carefully. Autoimmune conditions naturally fluctuate, so it is easy to credit or blame fasting for changes that would have happened anyway.
- Eat enough. Sustained under-eating can increase fatigue and lead to muscle loss.
- Look at the bigger picture. Sleep, stress, physical activity, not smoking, and overall diet quality all matter.
If You and Your Doctor Decide to Try It
If your specialist agrees that intermittent fasting is reasonable for you, a gentle approach is usually safest:
Start with 12:12 or 14:10
For example, eat between 9 AM and 7 PM. This is easy to maintain and keeps meals regular for medications that need to be taken with food.
Consider 16:8 only if the gentler schedule is going well
For example, eat between 8 AM and 4 PM or 10 AM and 6 PM, while still meeting your energy and protein needs.
Extended and fasting-mimicking protocols
Multi-day fasts and fasting-mimicking diets are more demanding and should only be done with medical supervision, if at all. See our fasting-mimicking diet guide for background.
Avoid: fasting during active disease or flares
Longer fasts during a flare add stress and increase the risk of undernutrition.
Frequently Asked Questions
Will fasting reduce my CRP?
Possibly, but not reliably. Some studies report modest reductions in CRP with intermittent fasting, particularly alongside weight loss, while others find no meaningful change. CRP is also affected by infections, injuries, and disease activity, so a single reading says little.
Can fasting cure autoimmune disease?
No. There is no evidence that fasting cures autoimmune disease. At most, research suggests it may affect symptoms in some conditions, and even that evidence is limited.
Should I stop my medication if fasting seems to help?
No, not without your specialist’s advice. Symptoms fluctuate naturally, and the underlying disease can remain active even when you feel better. Stopping treatment can lead to flares or lasting damage.
Why do I sometimes feel better while fasting?
Some people feel lighter or less sluggish when fasting, which may relate to smaller meals, avoiding trigger foods, or weight loss. Feeling better in the short term is not the same as a change in disease activity, so keep tracking symptoms and attending check-ups.
Does autophagy from fasting reduce inflammation?
Autophagy and inflammation are linked in laboratory and animal studies, but there is no established evidence that fasting-induced autophagy improves autoimmune disease in people. Claims that “autophagy cures autoimmunity” are not supported.
Which conditions have been studied most?
Rheumatoid arthritis has the longest history of small clinical studies, mostly involving supervised fasts followed by dietary change. MS and IBD research is at an early stage and largely in animals or pilot studies. For most other conditions, there is little direct evidence.
The Bottom Line
Fasting and weight loss can influence some inflammatory markers, and several autoimmune conditions are being studied. Rheumatoid arthritis has the longest, though still small, research history; psoriasis, MS, and IBD evidence is limited or early; and for most conditions there is little direct evidence. Fasting is not a treatment for autoimmune or inflammatory disease and should never replace prescribed care. If you are interested in trying it, discuss it with your specialist first, start gently, avoid fasting during flares, eat enough, and track your symptoms.