Fat Rats

See this summary of a scientific paper arguing that typical lab rats (and mice) are overweight as they eat all they want and get little exercise. This may make research results based on the rodents only relevant to overweight humans, which is to say, most of us. The paper in Nature has one very interesting implication:

Studies showing that caloric restriction can extend lifespan may have to be reinterpreted. "A major reason the lifespan of rats and mice is extended by caloric restriction is they started from an unhealthy baseline," argues Mattson.

Mark Mattson is chief of the National Institute on Aging's Laboratory of Neurosciences and a coauthor of the paper.