Regular readers of this blog might remember a post I wrote a few months ago about weight-loss surgery. A mouse study suggested that surgery works — triggering weight loss and, often, diabetes remission — not because it makes the stomach smaller, but because it drastically changes its biochemistry.

I took a close look at that study and a slew of others in a feature published in today’s issue of Naturetoday’s issue of Nature. Rodent models have shown that after surgery, the gut goes through many dramatic changes. Bacterial compositions shift, for example, bile acids flow more freely, and the intestines swell.

That last bit maybe isn’t so surprising — after all, once the stomach shrinks to the