Can a Keto or Carnivore Diet Help IBS? Exploring the Potential of Low-Carb Diets for Gut Relief
Irritable Bowel Syndrome (IBS) is a common yet complex gastrointestinal disorder that affects an estimated 10–15% of people worldwide (Harvard Health Publishing). Characterized by abdominal pain, bloating, gas, diarrhea, and constipation, IBS can make daily life unpredictable.
While dietary triggers vary from person to person, emerging research suggests that very low-carbohydrate diets—such as the ketogenic or carnivore diet—may offer relief for some. The reason lies in how carbohydrates interact with gut bacteria and the gut–brain axis.
The Carbohydrate–Gut Bacteria Connection
Carbohydrates, especially fermentable ones like those in the FODMAP family (Fermentable Oligo-, Di-, Mono-saccharides and Polyols), are a primary fuel source for gut bacteria. In healthy digestion, fermentation helps maintain a balanced microbiome and supports short-chain fatty acid (SCFA) production—important for colon health.
In IBS, however, there’s often an imbalance or overgrowth of bacteria in the small intestine, known as Small Intestinal Bacterial Overgrowth (SIBO). When these microbes ferment carbohydrates too aggressively or in the wrong part of the gut, the result is familiar: bloating, discomfort, and irregularity (Cleveland Clinic).
Reducing fermentable carbohydrates can “starve” the overgrown or misplaced bacteria, calming gut fermentation and easing IBS symptoms (Monash University).
Why Keto and Carnivore Diets May Help
1. Keto Diet: Low-Carb, High-Fat for Microbial Reset
The ketogenic diet limits daily carbohydrates to about 20–50 grams, focusing on fats (olive oil, avocado, fatty fish) and moderate protein. By drastically reducing carb intake, keto limits fermentable substrates for gut microbes.
This can:
Decrease gas and bloating
Reduce intestinal inflammation
Improve gut–brain signaling and motility
Early studies suggest ketogenic diets may decrease gut inflammation and improve IBS and IBD symptoms (MDPI – Nutrients Journal).
2. Carnivore Diet: The Ultimate Elimination
The carnivore diet removes all plant foods—focusing solely on animal products such as:
Meat
Fish
Eggs
Animal fats
This eliminates fiber, sugars, and FODMAPs entirely. For some, it represents the most complete elimination diet available, particularly when low-FODMAP or gluten-free diets fail. Reported benefits include:
Zero fiber fermentation (no substrate for gut bacteria)
Minimal irritation from plant compounds
Simplified digestion and nutrient consistency
Though still emerging, case studies show symptom improvements in inflammatory and functional gut disorders using ultra-low-carb diets (PMC – Case Report: Carnivore–Ketogenic Diet).
What the Science Suggests
While long-term trials are limited, several findings are consistent across studies:
Keto diets can reduce gut microbial diversity but also lower inflammation and symptom severity in IBS (MDPI – Nutrients Journal).
SIBO patients often respond well to low-carbohydrate diets that limit fermentable fibers (Cleveland Clinic).
Carnivore approaches remain largely anecdotal but are being explored as therapeutic elimination protocols for GI conditions like IBS and Crohn’s disease (PMC – Carnivore–Ketogenic Case Report).
Potential Drawbacks and Considerations
While promising, low-carb diets are not universally beneficial and can carry trade-offs:
Nutrient deficiencies (fiber, vitamin C, folate, antioxidants)
Reduced microbiome diversity with long-term carb elimination
Adaptation effects like fatigue, constipation, or “keto flu”
Sustainability challenges due to food restrictions
Those with chronic conditions should consult a gastroenterologist or dietitian before starting any restrictive diet (Harvard Health Publishing).
Final Thoughts
Keto and carnivore diets may offer relief for some IBS sufferers by reducing bacterial fermentation, calming gut inflammation, and stabilizing digestion. However, they’re best viewed as short-term therapeutic tools, not lifelong regimens.
The most effective diet for IBS is one that balances symptom control, nutrition, and sustainability. For many, that means combining low-carb phases with gradual reintroduction of low-FODMAP foods once symptoms stabilize.
Understanding your gut’s relationship with carbohydrates—rather than eliminating them entirely—remains the key to lasting digestive balance.