Dieters sometimes complain that they gain weight just by looking at food.

There’s no proof that really happens.

But a study published recently in the Proceedings of the National Academy of Sciences suggests some people derive more calories from their food than others.

The reason? Microscopic organisms called archaea [arr-KEE-uh] that live in the intestines.

Archaea help extract energy from fiber that would otherwise be undigestible. This process can increase your caloric intake by up to ten percent.

Most adults have high levels of archaea in their systems. And the more archaea you have, the more likely you’ll put on weight.

To gauge the impact of archaea, researchers devised an experiment, using genetically altered mice with no naturally occurring germs in their bodies.

They divided the mice into groups and inoculated them with three types of microbes, alone or in combination.

The results showed mice gained the most weight when given a common form of archaea plus a bacterium that feeds on fiber.

Apparently, archaea enhances the bacterium’s abity to process undigested fiber, causing fat stores in the mice to increase almost fifty percent.

The two microbes also reproduced up to one thousand times faster in each other’s presence.

Researchers concluded that medical professionals may one day help people gain or lose weight by manipulating the number of archaea in their systems.

Until that happens, dieters may feel less enthused about these hard-working microbes. Archaea are mankind’s friends, but frustrated fat-fighters might say, with friends like this, who needs enemies?