Sticking to diets is about more than willpower -- complexity matters

BLOOMINGTON, Ind. -- Many people think the success of dieting, seemingly a national obsession following the excesses and resolutions of the holiday season, depends mostly on how hard one tries -- on willpower and dedication. While this does matter, new research has found that a much more subtle aspect of the diets themselves can also have a big influence on the pounds shed -- namely, the perceived complexity of a diet plan's rules and requirements.

Cognitive scientists from Indiana University and the Max Planck Institute for Human Development in Berlin compared the dieting behavior of women following two radically different diet plans and found that the more complicated people thought their diet plan was, the sooner they were likely to drop it.

"For people on a more complex diet that involves keeping track of quantities and items eaten, their subjective impression of the difficulty of the diet can lead them to give up on it," reported Peter Todd, professor in IU's Department of Psychological and Brain Sciences.

Jutta Mata, now a professor of psychology at Stanford University, said this effect holds even after controlling for the influence of important social-cognitive factors including self-efficacy, the belief that one is capable of achieving a goal like sticking to a diet regimen to control one's weight.

"Even if you believe you can succeed, thinking that the diet is cognitively complex can undermine your efforts," she said.

Dieting is not all in one's head -- environment matters, too, the professors say. The physical environment has to be set up properly, such as putting snack foods out of sight to avoid mindless eating. But the cognitive environment, they say, must also be appropriately constructed, by choosing diet rules that that one finds easy to remember and follow.

For people interested in following a diet plan, Mata suggests they take a look at several diet plans with an eye toward how many rules the plans have and how many things need to be how many things need to be kept in mind.

"If they decide to go with a more complex diet, which could be more attractive for instance if it allows more flexibility, they should evaluate how difficult they find doing the calculations and monitoring their consumption," she said. "If they find it very difficult, the likelihood that they will prematurely give up the diet is higher and they should try to find a different plan."

About the study: The study examined both the objective and subjective complexity of two diet plans. Brigitte, the cognitively simpler of the two, is a popular German recipe diet that provides shopping lists for the dieters, thus requiring participants to simply follow the provided meal plan. Weight Watchers assigns point values to every food and instructs participants to eat only a certain number of points per day. The 390 women involved were recruited from German-language Internet chat rooms dealing with weight management and were already in the midst of using one of the two diet plans. They answered questionnaires at the beginning, mid-point and end of an eight-week period.

While losing weight initially isn't rocket science, keeping it off remains a challenge to dieters. It generally is believed that the longer people can adhere to their diet plan, the more successful they will be long-term with their weight loss maintenance. And the more like rocket science one's diet plan feels, Todd and Mata report, the less likely that long-term adherence and maintenance is to succeed.

The study, "When weight management lasts: Lower perceived rule complexity increases adherence," was co-authored by Sonia Lippke at the Free University Berlin and published online by the journal "Appetite." The article will appear in the next print edition of the journal. For a copy of the article, contact newsroom@elsevier.com.

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