Does candy make you slimmer? Or, how to confuse cause and effect

If you read the recent headline on, “Sweet! Candy eaters surprisingly slimmer,” you might think that candy is the next diet food. Sadly, this is far from factual. Based on a dietary recall study of 15,000 adults over the age of 19 surveyed between 1999 and 2004, the report concludes that those who eat chocolate and other sugary candies have smaller waists, a lower body mass index (BMI), a 14 percent decreased risk of high blood pressure and a 15 percent lower risk of metabolic syndrome than those who do not indulge in the treats.

But after reading further, you learn that only 20 percent of those surveyed reported eating candy at all, and even the study authors caution that eating candy does not cause weight loss. Instead, they hypothesize that candy eaters may simply exercise more in an effort to compensate for the extra calorie consumption.

“This is an excellent example of how to manipulate data to confuse cause and effect,” says ACSH's Dr. Gilbert Ross. “It’s much more likely that those who avoided eating candy were those more concerned about their weight. Further, dietary recall is a weak method for assessing correlations between food intake and health outcomes because many people forget what they’ve eaten the day before. The participants who reported eating candy claimed they ate very little of it (1.3 ounces per day on average) — not enough to cause weight problems — and the authors provide a hypothesis that was never tested in their study.”