'Protein cycle' can burn extra calories

HERSHEY, Pa., Sept. 5 (UPI) -- U.S. scientists have discovered a potential way for people to eat as much as they like but remain slim and energetic.

Christopher Lynch and colleagues at the Pennsylvania State University College of Medicine discovered they could activate an energy-draining but otherwise futile, cycle of protein synthesis in mice by disrupting an enzyme involved in the metabolism of some amino acids.

The enzyme-deficient animals showed elevated blood levels of the essential amino acid leucine, an important nutrient signal, and became slimmer than normal mice despite eating more food. They also showed "remarkable" improvements in glucose and insulin tolerance, and resistance to becoming obese on a high-fat diet, the researchers reported.

"The mice on the outside look normal, just skinnier and smaller," Lynch said. "After looking at their metabolism, we found that for the same activity, they were using more energy."

Moreover, the researchers found the animals that ate the most food also expended the most energy. "That would be ideal for people who are overweight," Lynch said. "They could continue to eat and just waste the energy and be thin."

The study appears in the journal Cell Metabolism.