Artificial sweeteners don't have any calories, but they might make you fatter than real sugar.
In a study recently published by Purdue University psychologists in Behavioral Neuroscience, rats given saccharin-sweetened yogurt actually ate more and gained more weight than rats given regularly-sugared yogurt.
Rodent studies should always be taken with a grain of salt, but the findings strike a potentially disturbing note for the millions of people whose hopes of a shortcut to slimness have fueled a billion-dollar artificial sweetener industry.
The problem appears to be one of metabolic regulation: when rats ate sugary yogurt, their core body temperature rose, ostensibly to take advantage of a calorie-rich nutrient source. But when rats ate the saccharin-sweetened yogurt, their body temperatures rose only slightly, and they ate more and gained more weight than their counterparts.
How could this be? The mechanisms aren't entirely clear: perhaps the rats, confused by false sweetness, became artificially sluggish, and thus less able to burn calories. Perhaps they were primed by the sweetness to expect a burst of calories, and when that didn't follow, they kept eating and eating. Perhaps both.
The findings, note the researchers, seem counterintuitive -- but they could hint at why diet sodas have been tied to metabolic disorders.
Role for Sweet Taste: Calorie Predictive Relations in Energy Regulation by Rats [Behavioral Neuroscience] [.pdf]
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Image: Chris Hoare*
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