Small intestinal bacterial overgrowth (SIBO) is a serious condition affecting the small intestine. It occurs when bacteria that normally grow in other parts of the gut start growing in the small intestine. That causes pain and diarrhea. It can have mild symptoms or full-blown malabsorption. Small intestine fungal overgrowth (SIFO) occurs when excessive amounts of fungus populate the small bowel. If SIBO is left untreated it can lead to other conditions such as IBS, leaky gut, obesity, acne, anemia, fatigue and an increase of symptoms in gut-brain disorders such as anxiety, depression, and autism.

It can also cause weight gain. SIBO can slow down metabolism and affect your insulin and leptin resistance, both of which help regulate hunger and satiety. The most common symptoms of SIBO include: Abdominal pain/discomfort. Bloating and abdominal distention. Diarrhea. Constipation (generally associated with methanogens). Gas and belching. In more severe cases, there may be weight loss and symptoms related to vitamin deficiencies.