Losing Weight – Gaining it Back…and the Microbiome

Today, for your reading pleasure, a kind of amazing 14 month long clinical trial out of Ben-Gurion University, in Israel![i]  As I am sure you all know, after dieting and losing weight, it is incredibly difficult to keep it off.  I read, not that long ago, that the average person on The Biggest Loser regained 70% of the weight they’d lost within a few years of being on the show.  Can you imagine going through the effort of losing 200 or 300 pounds, only to gain 3/4 of it back?!  Over the years, I’ve read a lot about the potential reasons for this including lapsing back into bad eating habits, the desire of the body to return to what it believes is “homeostasis,” lowered resting metabolic rates, etc.  The fact is, no one knows for sure but the microbiome has also become a huge target for research, with good reason.  We know that those who are lean versus not have radically different microbiome profiles.

Most people reach their lowest body weight after 4-6 months of dieting, and then tend to start regaining weight even if they continue to watch what they eat.  This international team of researchers, therefore, preserved the personal microbiome (froze the bacteria isolated from fecal samples) of the participants at that 6 month point.  The participants were assigned to one of three groups.  And this is where it gets REALLY interesting.  Group one dieted using healthy dietary guidelines.  Group two was put on the Mediterranean diet while group three was put on a green Mediterranean diet.  What is a green Mediterranean diet, you ask? (So did I!)  They were given something called Mankai, which is a specific strain of the duckweed plant, which was put into a green shake with green tea and 28g of walnuts.  This green drink led to the most significant change in the gut microbiome during the 6 month weight loss phase.

After 6 months, all 90 participants provided fecal samples that were processed into purified, odorless capsules.  The participants were then given either 100 capsules of their own microbiota or a placebo, which they ingested until month 14, the conclusion of the trial.

The results are crazy!  All 90 participants lost weight: on average, about 18.2 pounds.  However, only in the non-placebo green-Mediterranean diet group  was weight-regain limited to only 17.1%.  The rest, who got the placebo, or who did the other diets, regained on average, 50% of the weight they’d lost.  That is an incredibly significant result.

In an complimentary animal study, in which Mankai was given to rodents, the scientists were able to replicate these results, also noting the improved insulin sensitivity in the animals.  The belief is that Mankai optimizes the microbiome due to its protein and fiber content:  “”The nutrition-microbiome axis has been proven in this study as high polyphenols diet, and specifically, Mankai, a protein-based plant and dietary fibers could ideally optimize the microbiome in the weight loss phase, to induce potent microbiome to recall the flora of germs related to regain attenuation and improved glycemic state after transplantation.”[ii]  They found that the green diet increased several species (Alistipes putredinis, Bacteroides vulgatus and Bacteroides uniformis) which were previously associated with leanness.

Mankai does not appear to yet be available for purchase. I found this company, Eat Mankai ,  that looks like it may soon start selling the product.  Perhaps they are undergoing some kind of regulatory process?  I don’t know.  But anyway, it really is a fascinating food:  it is the only plant source that contains all 9 essential amino acids, plus iron, folate and vitamin B12, on top of other nutrients.  I have signed up to receive their newsletters so I can stay on top of things for those of you who are interested.


[i] Rinott, E., et al (2020) Effects of Diet-Modulated Autologous Fecal Microbiota Transplantation on Weight Regain. Gastroenterology. doi.org/10.1053/j.gastro.2020.08.041.

[ii] https://www.news-medical.net/news/20200826/Consuming-personal-fecal-microbiome-when-dieting-may-limit-weight-regain-study-shows.aspx

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