Eating 'healthy' food may not make you fit: Study

A new study may have some important ramifications for beach season: Just because a food promotes fitness does not make it good for the waistline.

That was the basic finding of a recent study published in the Journal of Marketing Research. The analysis found that people who were chronically concerned about their weight and ate fitness-branded foods actually ended up eating more and working out less.

The report's findings may come as something of a shock to health-conscious consumers, many of whom spend a king's ransom at places like Whole Foods just to feed their dietary wants. Meanwhile, the study suggests there may be an inverse correlation between how people eat and how much they work out.

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"The fitness food puts the restrained eaters in double jeopardy…," Joerg Koenigstorfer, professor of sport and health management at Technische Universität München and the study's lead author, told CNBC in an interview.

As part of the study, people received trail mix labeled either "fitness" along with a picture of running shoes on the package or just "trail mix." Restrained eaters, or people who were watching their weight, ate more of the "fitness" mix rather than the non-fitness mix. A later study showed these same people also worked out less.

"They eat the fitness food, and they think they got closer to their long-term goal," Koenigstorfer said.

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The findings held true when the trail mix was framed as dietary permitted to restrained eaters. When the mix was presented as forbidden instead, the increased eating effect disappeared.

Researches chose to conduct the study in one day because "it's hard to manipulate a diet over the long run," Koenigstorfer added.

The results are especially noteworthy in the context of a population concerned about weight loss given soaring obesity rates. Two-thirds of adult Americans 25 years or older who are either overweight or obese, according to a study published this month in JAMA Internal Medicine, and want to lose weight.