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Gut bacteria might determine how well you lose weight

felix gussone

Reviewed by Felix Gussone, MD, written by Health Guide Team

Last updated: Sep 17, 2021
1 min read

According to a new study, the gut microbiome might have something to say when it comes to whether a weight loss attempt will have success or not.

Older research has shown that changing your diet can change the composition of your gut microbiome—a term describing all the microorganisms including bacteria, archaea, and fungi that live in the digestive system. 

The researchers looked at 105 people who participated in a commercial wellness program. They split them into two groups: 48 had lost over 1% of their body weight for a year, and the other 57 had a stable BMI over the same time. The scientists then looked at blood and stool samples from the participants. Thanks to the genetic material recovered from them, the researchers were able to deduce what gut bacteria were found in each group.

They discovered that some gut bacteria seemed to lead to resistance to weight loss, whereas others helped with weight loss. In the group that didn’t lose weight, the gut microbiome broke down starches easily, which means they broke down complex calories in food. In those who did lose weight, the researchers found more evidence of bacterial DNA that allows bacteria to grow. This means the bacteria ate more of the sugar from the participants’ diets before their bodies could absorb it.

The team suggests that, if you’re struggling to lose weight, you may be able to encourage more beneficial microbes in your gut by changing what you eat.


  1. Diener, C., Qin, S., Zhou, Y., Patwardhan, S., Tang, L., Lovejoy, J. C., et al. (2021). Baseline Gut Metagenomic Functional Gene Signature Associated with Variable Weight Loss Responses following a Healthy Lifestyle Intervention in Humans. mSystems. doi: 10.1128/mSystems.00964-21. Retrieved from