Post-diet weight gain: the microbiota’s anti-yo-yo effect

Regaining the lost pounds is the dread of all dieters. But a few grams of gut microbiota gained during the diet may be enough to limit this “yo-yo” effect.

Created 03 December 2020
Updated 06 May 2024

About this article

Created 03 December 2020
Updated 06 May 2024

Rigorous monitoring of food intake is often required to avoid the infamous post-diet yo-yo effect. But is there another solution? As it happens, transplanting to yourself your own gut microbiota acquired following the diet may do the trick. The idea certainly seems a little off-putting since it involves ingesting the microbiota present in the feces via capsules. It has shown promise, nonetheless.

A two-step “slimming program”

Let’s start from the beginning. Obese patients were subjected to an exercise program and one of the following three diets: the classic guidelines; the Mediterranean diet plus a handful of nuts (rich in polyphenols); or a “green” Mediterranean diet (less meat, more fish, and lots of vegetable products with a high polyphenol content, e.g. Mankai duckweed and green tea). Six months later, 90 participants had lost an average of 8.3 kilos. The researchers then prepared capsules containing the microbiota in their stool. Over the next eight months, 44 of the patients took capsules containing their own fecal microbiota, while the remaining 46 were given a placebo.

A controlled yo-yo effect

The results? Patients who followed a green Mediterranean diet and then took capsules containing their own microbiota regained only 1.6 kg in the eight months post-diet, whereas those who followed the same diet but received a placebo regained 3.6 kg. Members of the first group also maintained their waist size and insulin level (hormone that controls blood sugar level), an effect not observed for the other two diets.

Effect of green Mediterranean diet on microbiota

Ultimately, the green Mediterranean diet had the most significant effect on the gut microbiota and bodily functions. When followed by the regular ingestion of the microbiota present in the gut on its completion, this diet has the potential to profoundly modify the gut microbiota and limit the yo-yo effect. Specific bacteria and changes in sugar transport may be the cause.

Obviously, this experiment should not be tried at home!

Old sources


Rinott E, Youngster I, Yaskolka Meir A, et al. Effects of Diet-Modulated Autologous Fecal Microbiota Transplantation on Weight Regain. Gastroenterology. 2020.

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