It is often assumed that overweight and obese people are lazy and that is how they gained weight to begin with. New research, however, shows that following a junk food diet over a long period of time actually causes lethargy and laziness.
A study at the University of California-Los Angeles (UCLA,) to be published in the journal Psychology and Behavior, looked at the effect of diets on rats. The six-month study consisted of 32 female rats. They were split into two groups. The first group was fed an unprocessed diet that included corn and fish meal.
The second group of rats was fed a sugary processed diet, which the researchers equate to the typical junk food diet. This group was fed the typical American diet, filled with processed foods and fried foods, which is partly responsible for the staggering rate of obesity.
After three months of being fed the diet consistently, researchers noticed that the rats fed the junk food diet gained weight, while the group that was fed a nutritious diet did not. It showed that poor diet leads to obesity, which lowers motivation.
They also noted that the junk food group took more breaks and took twice as long to press a level to receive a reward. Consuming too much sugar and fat on a regular basis zapped their energy and they lost the will to perform simple tasks.
The lead author of the study was Aaron Blaisdell, a professor at UCLA and a member of the Brain Research Institute. He attributes the junk food diet not only as the cause of their obesity, but also as the cause of their lethargy and laziness. They were tired more easily. He said the processed food was the cause, rather than the effect.
After six months of feeding the groups of rats in the same way, they found that weight gain and lethargy were not the only issues. The group that ate primarily junk food had a higher rate of tumors, unlike that of the group that was fed a healthier diet, which had fewer and smaller tumors.
At that point, they swapped the diets for the two groups and waited to see any changes over the course of nine days. The overweight rats did not improve or lose weight, nor did the healthy rats gain weight or become lethargic. Their motivation levels remained the same as the previous six months. This proved that short term dietary changes had little or no effect on the mice. It is the long-term reliance on junk food that causes health issues.
Blaisdell also notes that humans have a similar reaction and junk food causes them to eat more food. Over time, this leads to obesity and laziness. He question whether it is a matter of poor discipline or the quality of food being consumed. While the occasional treat may not have a detrimental effect, following a junk food diet on a regular basis will cause obesity and feelings of lethargy. Avoiding processed foods is the best way to prevent obesity, increase mental alertness and stay motivated.
By Tracy Rose