In a seven-year study of mice they found that those with the highest metabolic rate lived the longest, raising the prospect that the effect could be mimicked in humans.
Scientists have long thought that a high metabolic rate was linked to a shortened life-span. The present discovery turns this century old belief on its head and changes dramatically our understanding of the regulation of life-span.
Metabolism is the means by which nutrients are broken down to smaller building blocks and chemical energy, which are used to make new body materials and to do work.
The researchers discovered that the most metabolically active 25% of the mice studied, far from having shorter life-spans, in fact lived 36% longer than the least active. If the same effects are mimicked in humans then the finding would imply that a higher metabolic rate could add an extra 27 years to the average human lifespan.
When the muscles of the most metabolically active mice were examined, they were found to contain factors that increased their metabolism by making it less efficient.
Although the scientists do not yet fully understand how these factors work, it is suspected that while the make the metabolism less efficient, on the positive side they reduce the generation of toxic by-products called "oxygen free radicals".