Weight gain is often blamed on too much fatty food and too little exercise. But Professor Allison and his research team say there may be reasons other than these traditional ones.
The researchers studied body weight changes in more than twenty thousand animals. The animals came from twenty-four populations of eight different species, or groups, across North America.
FAITH LAPIDUS: Each animal was said to be in early middle age for its species. Yann Klimentidis worked on the study with David Allison. Mr. Klimentidis said they considered animals with at least two body weight measurements in the past sixty years. At least one measurement was made in the last half of the twentieth century. One exception was non-laboratory rats. Their body weight was first measured in nineteen forty-eight.
FAITH LAPIDUS: The study involved creatures as different as large animals in research centers and rats living free around Baltimore, Maryland. All the animals demonstrated major gains in average body weight over ten-year periods.
For example, chimpanzees in captivity showed a thirty-three percent increase in weight each decade. Laboratory marmosets increased weight at a rate of nine percent per ten-year period. Laboratory mice became fatter at a rate of ten percent. And laboratory rats increased at a three-percent rate.
The study also showed that pet animals are fatter. The average house cat weighed almost ten percent more each decade. Dogs’ weight increased at a rate of three percent.
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2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25