Research has revealed that the frequency of bowel movements can provide significant insights into overall health. A study published in July 2024 by the Institute for Systems Biology (ISB) analyzed the bathroom habits of 1,425 participants, comparing their bowel movement patterns with demographic, genetic, and health data. The findings indicate that those who reported having bowel movements once or twice a day exist within a ‘Goldilocks zone’ associated with optimal health. Both excessive and insufficient bowel movements were linked to various underlying health issues.
The study categorized participants based on their reported bowel movement frequency: constipation was defined as having one or two movements per week, low-normal as three to six movements per week, high-normal as one to three movements per day, and diarrhea as four or more watery stools per day. The researchers, led by microbiologist Sean Gibbons, examined blood metabolites, chemistry, genetics, and gut microbiomes from stool samples, seeking associations with bowel movement frequency and other health markers.
The Health Implications of Bowel Movement Frequency
The results showed a correlation between bowel movement frequency and health, particularly among those identified as having constipation or diarrhea. Participants with less frequent bowel movements were often younger women with lower body mass indices (BMIs). Despite these factors, clear links emerged between abnormal bowel movement patterns and health complications. For instance, stool samples from individuals experiencing diarrhea contained higher levels of bacteria typically found in the upper gastrointestinal tract, while their blood samples revealed biomarkers indicating potential liver damage.
Conversely, participants who reported infrequent bowel movements had stool samples with elevated levels of bacteria associated with protein fermentation. According to bioengineer Johannes Johnson-Martinez, prolonged stool retention can lead to harmful microbial activity.
“If stool sticks around too long in the gut, microbes use up all of the available dietary fiber, which they ferment into beneficial short-chain fatty acids,” Johnson-Martinez explained. This process can result in the production of toxins that may enter the bloodstream, with metabolites like indoxyl-sulfate identified as particularly damaging to kidney function.
Potential for Health Improvement Through Dietary Changes
The study raises the possibility that individuals can improve their bowel movement frequency through lifestyle changes. Research suggests that the gut microbiome can adapt relatively quickly to new habits. A separate study conducted in 2025 in Germany found that inactive adults who engaged in resistance training two to three times a week experienced notable changes in their gut bacteria within just eight weeks.
Participants who fell within the ‘Goldilocks zone’ of bowel movement frequency reported higher fiber intake, increased water consumption, and more regular exercise. Their stool samples showed an abundance of bacteria known for fermenting fiber, which is crucial for maintaining a healthy gut environment.
A clinical trial published in 2025 indicated that individuals with a high presence of methane-producing microbes were particularly effective at converting dietary fiber into beneficial short-chain fatty acids. This underscores the importance of both fiber intake and the specific composition of gut microbes in determining health outcomes.
While many people may experience fluctuations in bowel movement frequency due to temporary factors like illness or diet, this study emphasizes the importance of recognizing what is ‘normal’ for each individual. The research, published in the journal Cell Reports Medicine, suggests that understanding and potentially adjusting bowel movement frequency could be a valuable strategy for enhancing overall health.
