Why Your Crash Diet Won’t Work

_MG_6779_r_RubyYehPhotographed By Ruby Yeh.
From Paleo to the juice craze, the constant rotation of fad diets in America tells us two things about the way we interact with food. For one thing, we know much less than we think we know about nutrition. Second, we're totally obsessed with quick fixes. Instead of doing the hard work it takes to make lasting changes in the way we eat, we turn to detoxes, cleanses, and crash diets — hoping to transform our bodies into lean, mean, fat-burning machines in a matter of days.
Looking for more proof that life just doesn't work like that? New research on rats shows that temporarily switching to a healthy diet has no impact on their health — or their weight.
The study in question, conducted by UCLA researchers and published in this week's issue of Physiology and Behavior, was designed to test the nature of the relationship between obesity and laziness. Female rats were placed on one of two diets for six months; half were given an unprocessed regimen of corn and fish meal, while the rest got to gorge on processed carbs and lots of sugar.
Unsurprisingly, the junk-food group gained a significant amount of weight — becoming the rat equivalent of "clinically obese" — after three months. The junk-food rats continued to gain weight and also performed worse than their clean-eating counterparts on tasks that offered rewards. The scientists concluded that the "laziness" they observed in the junk-food group arose as a result of the rats' poor diet.
Things got interesting, though, when the researchers turned the tables after six months, assigning a junk-food diet to the healthy group and vice-versa. They found that neither group was affected by the drastic diet change. The rats that were used to a junk-food diet didn't display any health benefits or weight loss after nine days on a healthy crash diet. Likewise, the short junk-food binge didn't seem to have significant adverse effects on the healthy food group.
Yes, this study used rats — not humans —to examine the effects of junk food and crash diets. But, the authors were confident that the results could prove true for humans as well, citing similarities between rats' physiological systems and our own. While this is by no means definitive proof of the ineffectiveness of crash diets and "detoxes," it seems to reinforce what many of us have figured out the hard way: A healthy lifestyle can't be created overnight. (Science Daily)

More from Diet & Nutrition

R29 Original Series