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Gut bacteria and weight loss

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    “We’ve known for a few years that obese mice transplanted with the intestinal community of lean mice lose weight and vice versa. (We don’t know why.) A similar experiment was performed recently on humans by researchers in the Netherlands: when the contents of a lean donor’s microbiota were transferred to the guts of male patients with metabolic syndrome, the researchers found striking improvements in the recipients? sensitivity to insulin, an important marker for metabolic health. Somehow, the gut microbes were influencing the patients? metabolisms.”

    If this is true then some of us are screwed. Perhaps those who experience success with overfeeding have excellent gut health and those who fail at overfeeding have crappy gut health?

    • This topic was modified 10 years, 7 months ago by NYC1234.
    • This topic was modified 10 years, 7 months ago by NYC1234.
    • This topic was modified 10 years, 7 months ago by NYC1234.

    Fortunately, it is possible to alter our microbiota by changing our diet. From your link: “When Cani fed a high-fat, ‘junk food’ diet to mice, the community of microbes in their guts changed much as it does in humans on a fast-food diet.”


    Thanks for the positive note, David. I’m curious to know what a a fast-food diet does to change or gut flora in such a beneficial way? Can you share more on this please?


    I think you may have misread. The article is suggesting that a high-fat, fast food diet has a negative effect on gut flora, in both mice and humans.

    To be honest, I’m not a fan of Michael Pollan and I don’t think he has enough evidence to support some of his claims, and I also don’t think there’s much to gain, at least at this point, from trying to manipulate our gut flora.

    But I think it’s also important to avoid fatalism. Obviously, life isn’t fair, and some of us have it easier than others in the health department (and no doubt some of us get better gut bacteria from our mothers), but we can all work to improve ourselves. There is no excuse to give up.

    I don’t agree with the article in every respect, but it would still be wrong to interpret it to mean that some people are screwed, as did the OP (though maybe he was joking). If you accept Pollan’s ideas about our microbiota, the article also points out that diet can be used to change it. We’re not doomed by our genome.


    There’s argument about why ‘high fat’ diets cause deleterious effects on the microbiota. Anything we eat but do not absorb fully will potentially feed the bugs (bacteria, fungi, whatever), which we can generally call fermentation.

    The effect of fermentation (positive, negative) depends on the selectivity of the feeding (which bugs eat what), which depends on the strains present and the foodstuffs being fermented.

    Almost everything can be fermented.

    Simple sugars can be fermented by almost everything, so the benefit goes to the bugs which are faster growers and dividers (generally more pathogenic); hence why glucose or fructose mal-absorption is big trouble.

    Various fibers can be fermented, and there is broad variability in the effect, since some fibers (such as some types of ‘resistant starch’ and fructooligosaccharides like inulin) preferentially feed the good guys (like bifido) and some longer chain carbs preferentially feed the bad guys.

    Protein is less universally fermented, which highly advantages the bugs which can eat nitrogen compounds efficiently, like klebsiella and clostridium. Thus, too much protein, overtime, can lead to an increase in pathogenic strains.

    Fat is, as I understand, not fermented (at least negligibly so). But the bile acids used to digest fat are fermented selectively by a relative few strains which have adapted to this, which includes the newly discovered Bilophilia.

    In the case of the high fat diet, at least two things are going on here:

    1) The increase in bile acids needed for fat digestion increase the presence of bugs that can eat bile acids (like bilophilia)

    2) The high fat diet was also low in carbs, and therefore low in substrates that would feed non-fat-eating bugs. Thus, these bacteria, including bifido and other generally-accepted-to-be ‘good bugs’ would be starved.

    Some believe that the latter is far more important than the former, and that a high fat diet that is also high in inulin or resistant starch type fibers would suffer ZERO or NEARLY ZERO deleterious effects.

    One could ask the questions: so what?

    Well, I think this is important to note how many long-time low carbers have some serious problems after months to years of low carbing, including autoimmune and metabolic issues. In fact, in the one year all-meat diet at Bellevue Hospital, I believe it was Andersen who ate a sandwich on his first day back from the year of only meat, and ended up in the hospital the next day needing intravenous antibiotics for a serious pneumonia infection. The researchers didn’t know what to make of that, but they added that comment into the end of the paper.

    I think we now know what to make of it: the zero carb, high protein diet selectively bred relatively pathogenic, protein-consuming bugs, while it starved the good guys. As soon as he ate some easy-to-digest starch (everything can eat glucose and short glucose units), the bugs went wild. I think supplementing with inulin for a week or two as a transition from the low carb diet to the more typical diet could have prevented the whole shebang (my hunch).

    To now get to the original question: are some people screwed? Yes. If the necessary strains are present but just dwindled in number, changing the diet may alleviate everything by re-balancing the proportions of the various strains. Eating more inulin, tubers, and fruits, and less simple sugars and protein (but still getting enough protein) will re-balance things within a few months to years. Even biofilms won’t stand a chance, since well-fed bifido can destroy pathogenic biofilms.

    However, if the needed strains are simply NOT PRESENT, you’re screwed. My understanding is that many of the ‘needed’ strains don’t exist out-and-about, but only in our intestines. They have essentially been evolved for within our intestines, and they are only passed from one set of mucus membranes to another. So, vaginal births are good, C-sections bad. Prebiotics and vitamins good, antibiotics bad.

    The best hope for someone without the proper strains is to eat as well as you can, minding your symptoms, and to have lots of mucus membrane contact with other, healthier people (kissing, sex of all types); and to potentially get a fecal transplant, though I would keep that on the back-burner since it is very new and many things are yet to be worked out with that.

    This should not be thought of as exclusive to eating a nutrient-dense diet. The body has many tricks to deal with bacterial endotoxin and/or mycotoxin infiltration and so on when provided with ample nutrients. And also keep in mind, the deleterious effects of endotoxin (that is, the bad effects of bad bugs) are amplified in the presence of high PUFA, for several reasons including greater permeability of the intestines in the first place, and inability of the liver to be able to quickly and quietly detox the garbage coming in from the intestines.

    So, eat well, have some hot sex, kiss everybody as if you were Italian, and go from there.


    Thanks, that’s really helpful.


    Basically, gut bacteria won’t directly cause you to lose weight. Instead, it’s the effects of their activities rippling through your body which can help lose, gain, or maintain your weight because they help determine how much energy your body absorbs, and also how hungry or full you feel.


    2 gut bacteria are associated with lean body weight. Christensenella minuta and Akkermansia muciniphila are good gut bacteria for weight loss because they are linked with preventing weight gain and are often found in slim individuals.

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