Weight loss is hard. Microbial gut squatters can make it harder, or easier.


cartoon showing bacterial species in the intestinal tract

It’s hard to lose weight. It’s even harder when the microorganisms living in your gut are resistant to your weight loss efforts. On the other hand, if you have a bunch of microbial gut squatters that are willing to work with you, then with the proper diet and exercise plan, you’ll be slipping into those skinny pants in no time. A recent study suggests that the microorganisms living in our gut influence our response to weight loss interventions.


Why those little…

Hate to break it to you. But the human digestive tract is essentially a 30-feet-all-inclusive resort for over 100 trillion resident microorganisms (some good, some bad, and some just kind of hanging out for the free breakfast.) As long as we eat, they’ll eat. Our gut squatters help break down complex sugars into simple sugars that are more easily absorbed into our bodies. The presence of certain bacterial species may also impact gut inflammation and nutrient absorption. Gut microbe density may even affect how easily those simple sugars can get into their body.


So what’s the skinny on gut microbes and weight loss?

Gut microbes may affect weight loss outcomes in those working to lose weight. In the cohort study of 105 people enrolled in a diet and lifestyle coaching program, 31 gut microbial genes were found to be associated with weight loss. Evaluation of participants’ stool samples prior to the weight loss intervention found a much larger number of associations of bacterial genes with weight loss than baseline blood protein and dietary habits prior to enrollment in the coaching program. It’s unclear which bacteria were responsible for the gene expression markers, or what mechanisms may account for these associations. While more research needs to be done to support these findings, the results suggest that the composition of gut bacteria regulates our ability to lose weight.


Why it matters

The ability to lose weight and to sustain the weight loss may not simply be a matter of genetic makeup, dietary habits, and physical activity. Findings from this study and others suggest that gut microorganisms may play an active role in our weight loss outcome. The study did not track detailed dietary records throughout the full duration of the weight loss intervention. So while scientists extend the study and work out mechanisms of what and how gut microorganisms modulate the absorption of calories from the diet, we’d just have to stick to a healthy diet and lifestyle. While we can’t do anything about the genes we inherited (hey, we don’t pick our parents), maybe one day, we can pick the species of gut microorganisms that play nice with our weight loss interventions.