Excess body fat and obesity are an immune response to gram-negative gut bacteria, not a metabolic problem. Fix it by taking oral polymyxin, or a comparable antibiotic.
So they've established very firmly that gut bacteria are sufficient to cause excess body fat, but whether that's the main source in the general human population is unknown.
Quack quack goes the duck. I wouldn't use such an experimental treatment even on your pet rat.
(It does sound vaguely promising, like thousands of other candidate substances in translational medicine that didn't pan out.)
Edit: The paper is not from the journal Nature, it is instead from a different journal which is also published by the same company. The paper was published in The ISME Journal, with an impact factor of 7.4, compared to Nature's impact factor of 31! So next time, please do your research.
The paper is open access, but your link is blocked unless entered directly (they probably don't accept any non-site values for the HTTP referer field). This link should work.
Also, before you start taking antibiotics, here's the relevant part from that abstract:
The obesity-inducing capacity of this human-derived endotoxin producer in gnotobiotic mice suggests that it may causatively contribute to the development of obesity in its human host.
No mention of using antibiotics, polymyxin isn't mentioned once. As for the second study, there are reasons you don't administer polymyxin intravenously, and its intravenous efficacy is much different from when taken orally.
the effect sizes were huge in both experiments.
No, there were no antibiotics used in the ISMEJ article: " The volunteer lost 30.1 kg after 9 weeks, and 51.4 kg after 23 weeks, on a diet composed of whole grains, traditional Chinese medicinal foods and prebiotics (WTP diet, Supplementary Information; Supplementary Figure 1)"
So, it's reasonable to suspect that polymyxin would fix most human obesity too.
No.
Thanks for pointing out the journal error, that has been corrected. Also big thanks for the working link.
The "experiment" with the human subject in the ISMEJ article was stupid, which was why I didn't mention it. Everything I'm saying is based on the mouse experiments.
I do think your interpretation of these experiments is way too restricted. In a frequentist sense, everything you're saying is reasonable, since we don't know how well various results generalize (mouse to human, intravenous to oral, etc...). But in a Bayesian sense, this is pretty g...
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.