Do lazy people get fat? Actually, it may be the other way around—being fat might make you tired and more sedentary.
That’s the gist of a new study published in Physiology and Behaviour. Aaron Blaisdell, a scientist at UCLA, put thirty-two rats on two separate diets for six months. The healthy group ate unprocessed foods like ground corn and fish meal (yum?), and the unhealthy group ate processed food and more sugar. As you’d expect, that second group gained weight after a mere three months.
Then, Blaisdell had the rats perform a simple cognitive task: pull a lever, get some food. The fat rats ended up taking breaks that were twice as long as the healthy rats—which is odd, as you’d expect fat rats to be motivated by food.
Blaisdell also ran another test: he switched the rats diet for nine days, making the fat rats eat healthy food, and the healthy rats eat junk food. However, the rats performance didn’t change—suggesting that there isn’t a quick fix for fat-induced laziness.
“Overweight people often get stigmatized as lazy and lacking discipline,” Blaisdell said. “We interpret our results as suggesting that the idea commonly portrayed in the media that people become fat because they are lazy is wrong. Our data suggest that diet-induced obesity is a cause, rather than an effect, of laziness. Either the highly processed diet causes fatigue or the diet causes obesity, which causes fatigue.”