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Can Your Gut Bacteria Help You Lose Weight?

Can Your Gut Bacteria Help You Lose Weight?

Scientifically reviewed by: Michael A. Smith, MD

Wondering why weight loss is a struggle? It might have to do with the type of bacteria you have in your gut, according to research published by the American Society for Microbiology. "Your gut microbiome can help or cause resistance to weight loss and this opens up the possibility to try to alter the gut microbiome to impact weight loss," stated lead author Christian Diener, PhD.

The study followed individuals in a year-long wellness program that included lifestyle coaching and advice from a dietician or nurse. Researchers analyzed the gut bacteria of the 15 individuals with the largest reductions in weight and 10 individuals with the least weight loss.

Their findings? Among those who lost the most weight, there was an increase in gut microbiome genes that aid in the ability of bacteria to grow and multiply and assemble cell walls. Specifically, the team observed higher growth rates of the Bacteroidetes. Those who didn't lose as much weight had lower Bacteroidetes growth rates and fewer of these genes.

How does this connect to weight loss? According to Diener, if your gut bacteria grows at a slower rate, that may allow the body to absorb more sugar from the food that you eat.

"Before this study, we knew the composition of bacteria in the gut were different in obese people than in people who were non-obese, but now we have seen that there are a different set of genes that are encoded in the bacteria in our gut that also responds to weight loss interventions," Dr Diener explained. "The gut microbiome is a major player in modulating whether a weight loss intervention will have success or not."

Can gut health probiotics help you lose weight?

Now that we understand how bacteria in the gut may influence weight loss efforts, what's next? According to the study's authors, these findings are just the beginning; they recommended human trials to offer further insights on how gut microbiota and lifestyle interact to contribute to weight.

Probiotics that promote gut health and help prevent weight gain could be developed based on further discoveries.

How does losing weight improve your health?

The study didn't focus solely on the gut bacteria of the participants—it also looked at how weight loss changed overall health. Of the group that lost the most weight, there was an improvement in 7 out of 22 blood markers of metabolic health measured before and after the intervention, including an increase in adiponectin (levels of which tend to be lower in people who are obese) and a reduction in C-reactive protein (CRP), a marker of inflammation.

"Thus, not only did the 'weight loss' group reduce their BMI during the intervention period, but they became metabolically and immunologically healthier as well," the authors remarked.



  • Diener, C et al. "Baseline gut metagenomic functional gene signature associated with variable weight loss responses following a healthy lifestyle intervention in humans." mSystems. September 2021. https://journals.asm.org/doi/10.1128/mSystems.00964-21
  • Borgeraas, H, et al. "Effects of probiotics on body weight, body mass index, fat mass and fat percentage in subjects with overweight or obesity: a systematic review and meta-analysis of randomized controlled trials." Obes Rev. February 2018. https://pubmed.ncbi.nlm.nih.gov/29047207/

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