Researchers Seek Clues to Obesity Epidemic

A new study published in the Proceedings of the Royal Society B suggests the current obesity epidemic goes way beyond eating too much and lack of physical activity. University of Alabama at Birmingham researchers suggest exposure to light, infections and epigenetics also may contribute to the battle of the bulge.

Obesity researcher David B. Allison, Ph.D., examined data on small primates called marmosets from the Wisconsin Non-Human Primate Center. He noted that the population as a whole showed pronounced weight gain over time; however, there was no compelling reason. The nature of the diet had changed, but controlling for the exact date of the change, easily doable with animals living in a controlled laboratory environment, only strengthened the phenomenon.

Allison analyzed recorded data on more than 20,000 animals for at least a decade, the scientists believe that their parallel (to humans') increase in obesity rates cannot be explained away by diet and activity levels alone. The variety of animals in the study, and their diets and lifestyles ranged too far for that conclusion, they added. The scientists studied cats, dogs, feral rats, laboratory rodents, monkeys and chimpanzees. The researchers collected 24 data sets and found that a pattern of weight gain emerged in all of them over time. In 23 of the data sets the proportion of animals classed as obese had gone up.

"And yet there was no single thread running through all 24 data sets that would explain a gain in weight," says Allison. "The animals in some of the data sets might have had access to richer food, but that was not the case in all data sets. Some of the animals might have become less active, but others would have remained at normal activity levels. Yet, they all showed overall weight gain," he wrote. “The consistency of these findings among animals living in different environments, including some where diet is highly controlled and has been constant for decades, suggests the intriguing possibility that increasing body weight may involve some unidentified or poorly understood factors."

Sources:

* University of Alabama at Birmingham: Why are we getting fatter? UAB researchers seek a mysterious culprit