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SIBO Weight Gain

Small intestinal bacterial overgrowth, or SIBO, is a digestive disorder often associated with symptoms like bloating, gas, and abdominal pain. However, one lesser-known aspect of SIBO is its potential to lead to weight gain. 

In this article, we'll discuss SIBO weight gain, potential root causes, and functional medicine treatments to address this complex condition. 

What is SIBO?

SIBO is a condition characterized by an excessive growth of bacteria in the small intestine. Normally, the small intestine contains relatively low levels of bacteria compared to the colon. However, in individuals with SIBO, these bacteria multiply and thrive in the small intestine, causing various digestive problems.

While most individuals with SIBO present with at least one digestive symptom, there are many people who may suffer from a variety of non-digestive symptoms related to SIBO such as acne, fatigue, anxiety, brain fog, and more. Your doctor may diagnose SIBO with a breath test or a combination of clinical symptoms and a stool test. However, SIBO is not well understood by many conventional providers. 

SIBO Weight Gain

The relationship between gut bacteria and weight has become an area of highly studied interest. Many studies suggest a bidirectional relationship in which SIBO can lead to weight gain and this subsequent weight gain can then cause worsening SIBO. One large review study found that individuals with obesity have a nearly threefold risk of developing SIBO than people without obesity (1).

Weight gain in people with SIBO is a complex issue, but there are several key factors that contribute to this phenomenon.


Your gut plays a crucial role in your overall health and weight loss efforts. Unfortunately, the presence of SIBO may lead to the breakdown of the intestinal barrier (i.e. leaky gut) and inflammation within the intestinal lining (2). This inflammation can disrupt hormones and the body's ability to regulate appetite, potentially leading to overeating and weight gain. However, treating gut issues may promote weight loss in certain instances. For example, our members often experience weight loss as an unexpected (but welcome) side effect of following a personalized gut healing protocol. See a Root SIBO protocol at the end of this article. Research backs this observation and some large studies have found that altering gut bacteria with certain probiotic or prebiotic blends may significantly reduce body weight and promote fat loss (3, 4, 5). 

Insulin Resistance

Insulin resistance is another condition related to SIBO that may contribute to weight gain or weight loss resistance. After eating a meal containing carbohydrates, your body releases insulin to bring blood sugar levels back to a normal range. Insulin resistance occurs when the body cannot properly respond to insulin signaling, which leads to higher blood sugar levels. Inflammation, the standard American diet, infection, and lifestyle can all cause insulin resistance. Some studies show that SIBO may also contribute to insulin resistance (6, 7). Unfortunately, insulin resistance often causes weight gain and/or difficulty losing weight. Learn more about our functional medicine approach to weight loss


Some people with SIBO suffer from bowel irregularities, like constipation, which can worsen bloating, gas, and abdominal pain. Bloating often feels like weight gain as your pants may not fit as well and your belly may look distended. As a result, we find many of these individuals do not have set meals, snack frequently throughout the day, and may choose low-quality food options due to discomfort and/or lack of energy. Over time, these habits can lead to gradual weight gain.

Functional Medicine for SIBO

Although SIBO is becoming more rapidly prevalent, most conventional healthcare providers do not know how to effectively treat it. Functional medicine takes a holistic approach to address the root causes of health issues, including SIBO. Learn more about the difference between conventional and functional medicine. Here are some functional medicine treatments and strategies for managing SIBO and its associated weight gain:

Dietary Changes

Individuals with SIBO may experience digestive symptoms after meals or after eating certain foods. We may recommend a short-term low-FODMAP diet for individuals with SIBO as this can help reduce bacterial overgrowth and significantly reduce symptoms (1, 2). Some common foods eliminated on this diet include wheat, dairy (lactose), onions, garlic, and high-fructose corn syrup.

The foods we eat feed our gut bacteria, for better or worse. Foods rich in fiber, like fruits, vegetables, whole grains, nuts, and seeds feed our beneficial gut bacteria and promote their survival. On the other hand, foods rich in added sugar, like sweetened beverages, pastries, and cookies, tend to feed the harmful bacteria that can worsen SIBO. Our Root dietitians can help you create a personalized meal plan to reduce added sugar intake (and sugar cravings) and increase dietary fiber for optimal gut health.

Healing the Gut

Like other gut issues, SIBO is a tricky condition that requires a specific protocol in order to treat the root cause and not exacerbate symptoms. We use a “5R protocol” that aims to

  1. reduce bacterial overgrowth with targeted antibiotics or herbal antimicrobials;
  2. replace missing digestive components (like enzymes, bile, or stomach acid);
  3. repair the intestinal wall;
  4. reinoculate the gut with beneficial bacteria;
  5. and rebalance your lifestyle to sustain these changes.

A true gut protocol to treat the root cause of SIBO can take many months, and requires both persistence from the individual and a skilled functional medicine doctor to develop an effective treatment plan.

Learn more about our functional medicine membership program

Supplement Protocol for SIBO

While a true gut healing protocol may vary depending on personalized testing, the most common supplement regimen we use for SIBO follows the 5R protocol and may include:

  1. Microbiome Balance: 1 capsule each morning before breakfast to gently remove overgrowth (1 bottle)
  2. Root Digestive Enzymes: 1 with each large meal up to three times a day for about 3 months or as desired
  3. SIBO probiotic: 3 capsules daily taken for about 3 months or as maintenance

Our favorite SIBO probiotic contains three different strains of spore-based probiotics and immune-boosting immunoglobulins to repopulate your gut bacteria for long term success.
microbiome supplement

Microbiome Balance

Gently Rebalance Your Gut
digestive enzyme supplement

Digestive Enzymes

Feel your best after eating
SIBO probiotic

SIBO Probiotic

Say goodbye to bloating for good

Key Takeaways

SIBO is a complex condition that has many associated symptoms like digestive discomfort, acne, fatigue, and weight gain. SIBO weight gain may be due to inflammation and dysbiosis within the gut, insulin resistance, or dietary preferences due to digestive discomfort. A functional medicine approach to SIBO may include a 5R protocol to remove bacterial overgrowth, replace crucial digestive factors, repair the intestinal wall, repopulate healthy gut bacteria, and rebalance your lifestyle to encourage remission. 

Get to the Root at Home 

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