Junk Food May Literally Make You Lazy

Junk food eaters sometimes get a reputation for being imprudent, short-sighted, or lazy. "Why else would you subject yourself to all that nutritionally questionable, fattening food? It's not worth saving a few minutes or a few dollars," say people who don't know the deliciousness of a Big Mac. But a new study suggests that junk food eaters may be physiologically caught in a self-reinforcing trap: eating a junk food diet may itself cause fatigue.

Researchers at UCLA fed test rats a sweetened, highly-processed diet, while the control group received a normal, whole-foods rat diet. While the junk food rats did gain weight quickly, there were even worse effects, too:

As part of the study, the rats were given a task in which they were required to press a lever to receive a food or water reward. The rats on the junk food diet demonstrated impaired performance, taking substantially longer breaks than the lean rats before returning to the task. In a 30-minute session, the overweight rats took breaks that were nearly twice as long as the lean ones.

In other words, the junk food rats became lazy. Although they didn't have a choice regarding their diets, certainly a human who is more fatigued is less likely to shop for healthy foods and prepare them at home than to order delivery or pull up to the drive-thru on the way home from a long day at work. Maybe this explains why fast food companies are slinging so many coffees and caffeinated beverages with their maximally unhealthy meals, too. If they didn't perk you up to compensate, you'd realize that diet was dragging you down.

Even more disturbingly, nine days off the junk food diet didn't improve the rats' performance. On the other hand, nine days of junk food didn't impair the healthy rats' performance, either. So while an occasionally junk food meal or snack won't necessarily help your health, it's not enough to fatigue you chronically, either.

Don't get caught in the cycle of eating something quick, getting tired, eating something quick again... until you're a run-down, overweight, unhappy mess. Life is tiring enough as it is without stacking the deck against yourself physiologically. No excuses — with a little planning, you can avoid junk food-induced fatigue and laziness.