Weight loss woes? Your gut microbiome—the community of bacteria in your intestines—may be partially to blame. Preliminary research, published in Mayo Clinic Proceedings, found that certain gut bacteria may help weight loss, while others may hinder it. The study’s 26 participants were aged 18 to 65, were overweight or obese, and were participants in the Mayo Clinic Obesity Treatment Research Program. For three months, they were put on a diet emphasizing large volumes of fruits, vegetables, and low-energy density foods, with the goal of reducing calorie intake while achieving high food intake. They were advised to walk at least 10,000 steps per day, measured by a pedometer, and they met weekly for group sessions focused on behavior modification skills such as self-monitoring, goal setting, and stress reduction. Researchers used stool samples, collected at baseline and three months, to understand the make-up of each participant’s gut microbiome. At the end of the study, researchers found that nine of the participants had lost at least 5% of their body weight, while the rest had lost less than 5%. After controlling for age, BMI, diabetes status, and other factors, researchers compared stool exams from those who did and did not lose 5% of their body weight, finding that:
Participants who lost at least 5% of their body weight had more Phascolarctobacterium bacteria in their gut microbiome.
Participants who lost less than 5% of their body weight had more Dialister bacteria in their gut microbiome. They also had a greater number of microbial genes associated with the production of carbohydrate-digesting enzymes.
After three months on the weight loss program, there were no significant changes in gut microbiomes in either of the two groups.
Researchers think these bacteria may process carbohydrates differently, which would contribute to their ability to help or hinder weight loss. Whether and why this is true remains unclear, as a greater abundance of Phascolarctobacterium species has been associated with weight gain in some animal studies. In addition, Dialister has been previously identified as a pathogen and it's possible role in metabolism is still unknown. One theory is that certain bacteria or combinations of bacteria may be better at metabolizing complex carbohydrates, creating byproducts that can be digested and absorbed from starches and fibers, thereby releasing calories that would otherwise be unavailable to us. While we wait for more findings on the gut’s role in weight loss, research shows that eating well and exercising is still the best way to achieve weight loss, and that sustaining healthy changes over the long term may help shift gut microbiome profiles toward those associated with metabolic and overall health.
Source: Mayo Clinic Proceedings