Obesity is a big problem, and UNLV biologist Allen Gibbs has enlisted millions of six-legged volunteers to help him figure out the genetic basis of a plight that affects an increasing number of Americans.

For nearly a decade, Gibbs has been breeding the world’s fattest fruit flies to investigate how they adapt – or don’t – to stressful environments.

Each generation of flies is starved, with those surviving (less than 20 percent) becoming the founders of the next generation.

More than 115 generations in, the flies have become experts at fat storing, retaining twice the level of typical flies. They also have traits resembling those found in obese humans, including heart problems, lying around not exercising, and poor sleeping habits.

In a study published January in the journal Molecular Biology and Evolution, Gibbs and his team compared the DNA of the fat fruit flies to a control group in the lab and found nearly 400 candidate genes potentially associated with obesity and other health problems. Fruit fly genes overlap with humans by about 70 percent.

“The results of our study speak to the evolutionary origins of obesity and provide new targets to understand the polygenic nature of obesity in a unique model system,” according to the study, "Genome-Wide Analysis of Starvation-Selected Drosophila melanogaster—A Genetic Model of Obesity."

Gibbs and his team found that obesity isn’t isolated in one gene, it’s much more complex with numerous candidate genes all contributing in some way to the result.

Feeding the fruit flies common household sugar, yeast and cornmeal, Gibbs has been able to begin to peel back the evolutionary origins of obesity and provide new targets for further research.

Gibbs’ work requires great sacrifice. At least on the part of the fruit flies.

Through starvation selection and the flies’ short lifespan, thousands make the ultimate sacrifice for science every month.

And while Gibbs said it’s for the greater good -- “I do believe I’ve developed some sort of bad fruit fly karma.”

The hope is that the flies’ sacrifice will result in scientists being able to one day be fight obesity in humans medicinally.

“What we’ve shown is that they have bad hearts. They sleep about 50 percent more than other flies. And they are so fat they can’t fly,” Gibbs said.

Of course “when we feed them less and exercise them more, they get healthier,” Gibbs said.

Just in case anyone is waiting for that magic pill.