Diet Induced Obesity Makes you Lazy, Study

Researchers reveal that it is diet induced obesity that makes people tired and lazy; dismissing the notion that sedentary lifestyle leads to obesity.

Researchers at the University of California, Los Angeles, based their finding on the study conducted on 32 female rats. The study, led by UCLA scientist Aaron Blasisdell, also claims that fatigue is an outcome of excessive intake of junk food.

In this study, the female rats were kept on one of the two diets for six months. In the first diet, the rats were fed their standard diet mostly unprocessed foods like ground corn and fish meal. In the second diet, the ingredients were highly processed and had more sugar, replicating junk food diet.

After three months the researchers noticed a significant difference in the weight of the rats. They saw that the 16 female rats kept on junk food had gained weight and were fatter.  .

As a part of the study, the female rats were given a reward taks whee on pressing a lever they were given a food-water reward.  Compared to the lean rats, the rats kept on junk food displayed impaired performance. During the 30 minute session, the obese rats took breaks twice as long as the rats that consumed the standard diet.

After six months, the researchers switched the diet. In this the obese rats were given a nutritious diet for nine days.  Unfortunately, this switch in diet didn't help the obese rats shed their excess weight nor did it improve their performance in the task.

The lean rats kept on junk food for nine days did not see a weight gain nor did it impair their performance in the task. 

The researchers said that this showed a diet of junk food led to obesity and cognitive impairment.

Implications for Humans:

The researchers strongly believe that this finding is equally applicable to humans as the physiological systems are similar to rats.  Junk food makes humans hungrier.

"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."

The finding was reported in the journal Physiology and Behavior.