This is scientific Americans 60 second science. I'm Karen Hopkins. Got a minute?

Think it's your inability to resist cheesecake that's making it tough to fit into your skinny genes?

Your bacteria may share some of the blame.

Because a new study in mice shows that the responsive intestinal microbes to a high-fat diet

ends up triggering the release of a hormone that makes mammals

feel hungry causing them to eat even more. The finding is served up in the journal

Nature. Previous work has shown that the types of bacteria in the gut in diabetic or obese individuals are different from the bacteria in healthy people.

But does this bacterial makeup contribute to these disorders or is it just a side effect?

To unravel this mystery, researchers put mice on a high-fat diet.

The animals experienced a buildup of a chemical called acetate, particularly in the large intestine. That location points to gut

bacteria which can produce acetate as a possible culprit. So the researchers

wiped out the microbes using antibiotics or a simple saline wash, and acetate levels plummeted.

Okay, so the gut bacteria in fat-fed mice make acetate.

What does acetate do? Well, it gets the involuntary part of the nervous system,

the parasympathetic nervous system, to put out the call to produce more insulin.

Unfortunately, in this case, acetate also gets the parasympathetic nervous system to stimulate

production of a hunger hormone called gerellen.

And the more fats an animal consumes, the more acetate it makes, which means the more gorellen it produces

and of course the more it eats

and bacteria make the whole sequence happen.

The researchers are now investigating

whether the same biochemical events happen in humans.

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