The term “junk food” has long been used to describe items with little to no nutritional value. The reason for this is fairly obvious – a steady diet of foods loaded with saturated fat, sodium and sugar tends to thicken the waistline, and can easily lead to long-term health problems. Aside from adding unwanted pounds, there is also reason to believe that unhealthy foods can sap the body’s energy supplies.
Junk Food in Rats
A recent study by UCLA researchers found that poor-quality diets made rats noticeably sluggish. Published in the April 10, 2014 issue of the journal Physiology and Behavior, this report monitored a total of thirty-two laboratory rats. At the beginning of the study, these test subjects were divided into two groups of sixteen. The first ate a mix of corn mash and fish meal, whereas the other sixteen rats were fed a steady diet of sugar-drenched processed items. Both groups were placed on their diets for a period of six months.
Three months into the experiment, the ill effects of the junk food diets became readily apparent to the researchers. By this time, the rats who subsisted on sugary fare had experienced large gains in weight. Not surprisingly, this weight gain did not occur in the other group of rats.
The research team also measured the rats’ energy levels. To do this, the researchers used a test in which the rats received food or water after pressing a lever. Due to the test’s straightforward design, the rats clearly understood that they would be rewarded after completing this task.
Despite this fact, the two groups behaved very differently during this experiment. While performing the test, the rats on the junk food diet took much longer breaks than their thinner counterparts. Specifically, these rats took breaks that lasted roughly ten minutes, about twice as long as the study’s healthier rodents. Essentially, this behavior indicated a lack of motivation on the part of the overweight rats.
After the six month mark had passed, the two groups switched diets. For nine days, the healthy rats were fed processed food, while the obese rats ate healthily for the first time in half a year. Despite completely changing the groups’ diets, the researchers found that the unhealthy rats neither lost weight nor displayed greater effort during testing. Likewise, the thin mice did not gain weight, and still completed tasks in a relatively short amount of time.
Perhaps most alarmingly, a significant number of tumors were discovered on overweight rats. In comparison, far fewer tumors were found on the rats that ate a healthy diet. The growths on the thinner mice were also much smaller in size.
Laziness Or Obesity – Which Comes First?
These findings raise a very interesting question – does laziness lead to obesity? Or does weight gain cause people to become less motivated? The study’s lead researcher, Dr. Aaron Blaisdell, argued in favor of the second explanation. In a press release detailing the study, Blaisdell stated that “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.”