Fat Dogs Are Colder Than Lean Dogs

Fat dogs tend to be colder than lean canines, according to a new study that identifies a possible relationship between weight gain and body temperature.

The findings, recently published in the International Journal of Obesity, could apply to humans and other mammals as well, according to the authors. Individuals who have a tendency to be cold may therefore be more susceptible to weight gain.

The entire process appears to happen internally, so you can't just enjoy that extra dessert with the "I'm cold" excuse.

Roberto Refinetti, a professor of psychology and associate dean at the University of South Carolina Salkehatchie, led the study.

"We don't fully know the causes of the obesity epidemic that the U.S. is experiencing," he said in a press release. "One possible cause that hasn't been studied is the relationship between a lower body temperature and obesity."

He and his team compared the rectal temperatures of 287 lean and obese dogs over several years. They found that larger dogs have lower temperatures than smaller dogs. Since size can be tied to the particular breed of dog and other factors, the scientists next focused on weight. They determined that, among canines of the same height and length, obese dogs have lower temperatures than lean dogs.

Most humans and other animals gain weight because they accumulate fat. That occurs when they take in more energy than they expend. The unused energy is stored as fat.

"The way to reduce energy intake is to eat less, but that means you feel hungry, and a common way to increase energy expenditure is to exercise, but many people lack the motivation," Refinetti said.

He believes it's possible that obesity may result from a less obvious reduction in energy expenditure: a reduction in body temperature. Warm-blooded animals, like humans and dogs, spend much of their energy generating heat to keep the body warm. However, some animals have body temperatures that are naturally lower and therefore do not need to use as much energy to stay warm.

The reduced body temperature would be sufficient to account for body weight gain over several months.

Refinetti concluded, "Although not yet replicated in humans, these results suggest that human obesity may be caused by a small reduction in the temperature at which the body maintains itself."