The more people eat “diet” versions of richer foods, the less they may actually like what they are tasting, a small study suggests.

The findings, reported in the American Journal of Clinical Nutrition, suggest that familiarity can breed dislike when it comes to reduced-calorie foods. They may also offer some insight into the common dilemma of “yo-yo” dieting, the researchers say.

For the study, researchers had 36 adults eat either a full-calorie spaghetti Bolognese for lunch five days in a row, or a reduced-calorie version of the same. The full-calorie prepackaged product contained 567 calories, while the diet brand contained 374 calories.

At each meal, the participants rated how well they liked the food after their first forkful, as well as whether they expected the meal to be filling and satisfying.

Overall, the researchers found, diners’ had a similar liking for both meals on the first day. But thereafter, appreciation for the diet version declined, with participants’ ratings declining by about 30 percent, on average.

In contrast, ratings for the full-calorie meal held steady over the five-day study.

The findings suggest that people’s taste for diet brands may decline as they become more familiar with them, according to senior researcher Jeffrey N. Brunstrom, of the University of Bristol in the UK.

However, there are many variables that could affect any one person’s willingness to stick with reduced-calorie products. Brunstrom and his colleagues found that while the diet pasta’s likeability took a dip, diners’ expectations as far as having their hunger satisfied remained steady.

“We found little evidence that people started to expect that the food would be less filling,” Brunstrom told Reuters Health in an email, adding that “this is good news for weight-loss foods.”

However, he noted, it’s unclear if those positive expectations would hold over weeks or months. In general, larger and longer-term studies are needed to better understand how people’s affinity for reduced-calorie foods shifts over time, according to the researcher.

Brunstrom and his colleagues also point out that their study focused on the palatability of a reduced-calorie main course, and not the lower-calorie snack foods so common on grocery store shelves. People’s taste for those products, the researchers note, may be better maintained.

An interesting question, according to Brunstrom, is whether changes in consumers’ taste for reduced-calorie products help explain why so many people find it hard to stick with a particular diet.

“Perhaps this is why people engage in ‘yo-yo’ dieting,” he speculated, adding that such on-again/off-again dieting is considered particularly unhealthy.

One of the co-researchers on the study is an employee of food manufacturer Nestle, which funded the work.

SOURCE: American Journal of Clinical Nutrition, online April 7, 2010.