Successful Dieting Could Be More in Your Head

The popular notion that success in dieting depends mostly on how hard one tries is widely regarded as sound thinking. But a new study shows that the perceived complexity of a diet plan’s rules might also key play a role in the success rate for participants.  In a recent online issue of the journal Appetite, researchers from Indiana University and the Max Planck Institute for Human Development in Germany reported the results of study hypothesizing that “if eating rules are perceived as too complicated from a cognitive point of view, people will be less likely to remember and process the information required by the rules, have more difficulty applying them, hence will be more likely to give up using them, and thus to abandon the subjectively-judged cognitively complex weight management program as a whole.”

The study1 looked at both the objective and subjective complexity of two diet plans, first looking at both books that form the basis of the plans, then conducting a longitudinal study of women already following either plan. The German recipe diet plan Brigitte, the cognitively simpler of the two furnishes shopping lists for the dieters, requires participants to follow a provided meal plan and is regarded as cognitively more simple of the two. In contrast, Weight Watchers, also used in Germany, assigns point values to each food, informing participants to consume only a specific number of points per day. The study’s 390 participants were women recruited from German-language Internet chat rooms that discuss weight management and who were already involved in using one of the two diet plans. They answered questionnaires at the start, the half-way point and end of an eight-week period.

The study found that 80 percent of the Brigitte dieters were able to adhere to the plan, compared with just over 72 percent for the Weight Watchers plan. And by measuring the attrition rate for both programs, the researchers noted that the more complex the diet plan was perceived as being for participants, the earlier they were likely to quit.

“The underlying assumption is that staying longer on a healthful weight loss or weight management program increasesthe likelihood of controlling weight or achieving generally betterhealth: short-term diets do not generate lasting effects2, while successful weight management programsinvolve long-lasting lifestyle change, including nutritional changes.3

“As we show, the regimens, Weight Watchers and a popular German recipe diet (Brigitte), strongly differ in objective rule complexity and thus their cognitive demands on the dieter,” the researchers wrote. “Perceived rule complexity was the strongest factor associated with increased risk of quitting the cognitively demanding weight management program (Weight Watchers); it was not related to adherence length for the low cognitive demand program(Brigitte).” The researchers also noted that the two groups in the study differed in several key aspects. On average, participants in the Brigitte plan were older than those who participated in the Weight Watchers plan. The nature of the goals also varied. In general, the study noted, ‘Brigitte participants were more likely to have a weight goal for their weight management program while Weight Watchers more often had a time goal.”

The researchers suggest that the data collected from this study and others like it could help make future diet plans more successful by limiting their complexity. “…designing weight management rules that can be adhered to for a long period or an entire lifetime — including by making rules that are not perceived as being too complex — could help limit the spread of overweight and obesity.”


1. When weight management lasts. Lower perceived rule complexity increases adherence. Jutta Mataa, Peter M. Todd, and Sonia Lippke. Appetite Volume 54, Issue 1, February 2010, Pages 37-43

2. Mann, T., Tomiyama, J., Westling, E., Lew, A.-M., Samuels, B., & Chatman, J. (2007).Medicare’s search for effective obesity treatments. Diets are not the answer.American Psychologist, 62, 220–233

3. Powell, L. H., Calvin, J. E., III, & Calvin, J. E., Jr. (2007). Effective obesity treatments.American Psychologist, 62, 234–246


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