Habituation is when people lose interest in something after being repeatedly exposed to it (insert your favorite joke about being married here).

When it comes to diet, it is hypothesized that habituation can decrease caloric intake.    That also means caloric intake will increase if you get a lot of variety.   Of course, habituation is a no-no in the modern world of nutritional variety.   We're not 19th century Irish peasants, we shouldn't just eat potatoes every day in order to stay thin.

The "food addiction hypothesis" purports that some people may overeat because they are insensitive to the normal habituation response and thus need even more exposure to a food to trigger 'disinterest' but there has been no rigorous research investigating whether healthy-weight and overweight individuals have different habituation responses, and little is known about what patterns of food exposure are most powerful in triggering habituation. 

Some believe the modern (and unprecedented) level of dietary variety help explain skyrocketing rates of obesity, though obviously eating too many calories is still the real culprit.   Others cite that some foods, even eating at all, can trigger release of various brain chemicals, some of which are also involved in what happens with drug addiction and withdrawal in some people.
A group of researchers writing in The American Journal of Clinical Nutrition studied long-term habituation in obese and non-obese women to try and find some new answers. 

Sixteen non-obese [BMI (in kg/m2) < 30] and 16 obese (BMI 30+) women were randomly assigned to 1 of 2 groups: the "weekly group" participated in weekly experimental food exposure sessions for 5 wk, whereas the "daily group" were studied daily for 5 consecutive days. During each 28-min experimental session, subjects were asked to complete a variety of tasks after which they were "rewarded" by being given a 125-kcal portion of macaroni and cheese. Participants could work for as much food as they wanted. The researchers then evaluated total energy intake.

Whereas weekly food exposure increased total caloric intake by approximately 30 kcal/d, daily exposure decreased energy consumption by ~100 kcal/d. This supports long-term habituation in terms of caloric intake. Very few differences were found between how obese and nonobese individuals responded.

The authors concluded that reducing variety in food choices may represent an important strategy for those trying to lose weight. Moreover, having a person even remember that they have eaten a certain food recently may be effective in this regard.

This leads to questions about whether school-lunch planners and public health officials should reconsider diversity in the menu because it might "be associated with promoting excess food intake and increased body mass index."

Food for thought?