Finding the cause "will allow us to investigate medications and therapies" that could turn something in the body on or off, he said.
Not all obese people can get skinnier by eating less and exercising more, Weiss said. "The bottom line is that they may be able to eat less, but their bodies may be so efficient that they can extract calories from food much more effectively and may not be burning energy as efficiently as others," he said.
This fact leads to unhappy news for some obese people, he said. "If you're eating just one pea and you're gaining weight, you'll have to cut the pea in half."
Still, the future could bring genetic tests for patients that could allow doctors to tailor treatments to their particular bodies, he added.
The U.S. National Institutes of Health has more on obesity.
SOURCES: Philippe Froguel, M.D., Ph.D., professor and head, genomic medicine, and Alexandra Blakemore, Ph.D., senior lecturer, Imperial College London; Stuart Weiss, M.D., clinical assistant professor, medicine, NYU Langone Medical Center, New York City; Feb. 4, 2010, Nature
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