High protein, low carb, calorie restricted diets linked to positive gut outcomes, study asserts

The research was published in the journal Biomedicines​.  It was the work of researchers associated with several hospitals, universities and research institutes in France.

The goal of the research was to document the shifts in microbiome makeup among more than 200 subjects who were undergoing a ’real world’  weight loss program.  All of the subjects were following calorie-restricted diets and some of them were using a probiotic supplement as well.

The researchers based their study design on the use of enterotypes to characterize the makeup of gut bacterial species. This concept was first put forward in a 2011 paper published in the influential journal Nature​​​ by a group led by German researcher Peer Bork, PhD, which postulated that the distribution of species within the human gut could be put into several different buckets he termed ‘enterotypes.’  These then could subsequently be more easily linked to disease states and health outcomes as opposed to in effect looking at human gut microbiome makeups on a number line with a broad and, presumably, unwieldy distribution.

Are ‘enterotypes’ valid?

The validity of the concept has been challenged by other microbiome researchers, notably in a 2014 paper by a group led by Rob Knight, PhD​​, now with the University of California, San Diego.  That paper argued that, while the concept is undeniably attractive, “[S]everal different methods of collapsing enterotype variation into a few discrete clusters suggest that enterotype distribution is continuous and can vary widely within an individual.”​

Despite those misgivings, the simplicity offered by the approach has gained traction within the research community. It has as featured in several studies, such as a 2017 study looking at gut microbiome makeups among Crohn’s disease sufferers​​ and another paper put out in 2020 looking at the effects of statin therapy on the gut​​.  Both of those papers were also published in Nature​, showing that whatever criticisms other researchers might have, that journal’s editorial board has not backed away from the concept.

Cohort of ‘real world’ weight losers

In this research the authors were looking at how subjects’ guts changed over time while participating in a weight loss program to which they were referred by their physicians. The paper’s authors specifically were looking at outcomes relating to the so-called ‘Bacteriodes 2 (Bact2) enterotype.’  That is defined as a specific microbiome composition enriched in the relative abundance of Bacteroides genera and featuring a low overall cell count.  According to the researchers, it has successfully been associated with obesity.

For their study cohort the researchers recruited 263 volunteers undergoing a standardized weight loss protocol developed by a French health care provider which consists of three phases.  Phase one is a high protein, low carbohydrate calorie-restricted diet (800 to 1,100 calories a day) for eight weeks. That is followed by a transition phase in which normal foods are reintroduced followed by a follow-up phase that includes nutritional coaching support to help maintain weight loss.

All of the participants were also recommended to take what was referred to as a ‘live microbial product’ with 11 different probiotic strains.  A bit more than a quarter of the subjects did not use the supplement. The subjects also took multivitamin/mineral supplements to avoid nutrient depletion with the low calorie diets.

Subjects who started with low gut diversity benefited the most

All of the participants were successful in losing weight at the outset of the protocol. When delving into how all of this affected the subjects’ guts the researchers said the picture wasn’t very clear when looking at the whole cohort. So they decided to stratify the data based on how diverse the subjects’ gut were going in, and that’s when some significant effects were observed.

“In this real-world weight management program, a high-protein, low-carbohydrate diet led to significant improvements in gut microbiome diversity and composition, with reduced Bact2 prevalence, albeit mostly in subjects with low diversity at baseline,”​ they concluded.

“This study paves the way for future examinations of the Bact2 dysbiosis-related signature and could drive future personalized nutrition efforts to orient the microbiome towards a more favorable community composition for metabolic health,”​ they added.

Source: Biomedicines​​​
doi.org/10.3390/biomedicines10010016
Characterization of the Gut Microbiota in Individuals with Overweight or Obesity during a Real-World Weight Loss Dietary Program: A Focus on the Bacteroides 2 Enterotype​
Authors: Alili R, et al.