Why Do You Always Have Room for Dessert?

One of the key factors that contribute to how much we eat is the variety of different foods available. When people eat the same food during a meal they become habituated and decrease their consumption. However, when presented with a variety of foods during meals the amount consumed increases. Research consistently shows that exposure to a variety of foods results in overeating and weight gain. Thus, an understanding of the effect of variety on eating and satiety may be helpful for weight-loss intervention (Johnson & Wardle, 2014).

Source: By Ivan Baña (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Habituation (getting sick of things) is a decrease in response to a specific stimulus after repeated exposures. (Raynor and Epstein, 2001). Although people may find it particularly enjoyable when they initially start eating, but the extra pleasure wears off. People describe habituation as the food no longer tasting good, or being tired of eating. Habituation is a mechanism for termination of eating.

Habituation theory suggests that the presentation of a novel food can delay satiation. Varied foods act as novel stimuli. That is, we tend lose interest in a specific flavor, but remain interested longer when flavors keep changing (e.g., consuming chocolate brownies with vanilla ice cream).

The variety effect has been attributed to sensory-specific satiety. The term sensory specific satiety is defined as a decrease in appetite for the food that is eaten relative to non-consumed foods that have different sensory qualities, such as taste, texture, and appearance (Rolls et al., 1982). For example, a salad, followed by an entrée of meat, followed by a dish of ice cream. A greater variety of food leads people to eat more than they would otherwise. In an experiment where people were offered different varieties of sandwiches in sequence, they consumed 15 percent more calories than those who were repeatedly offered the same one.

The sensory-specific satiety explains why we always seem to have room for dessert even when we feel completely full from the main course. In part, it is because the dessert is the only part of the meal that we haven’t tasted. Desserts offer sensory qualities quite different from the main course (sweet vs. savory). So, being full and feeling sated are separate matters.

The variety effect explains why everyone overeats at an all-you-can-eat-buffet. In addition, sunk cost (advance charge for the meal) is a motivation factor to get one’s money’s worth. The price of another helping is exactly zero (Just and Wansink, 2011). Consequently, a buffet customer will overeat beyond the point of fullness.

From an evolutionary perspective, the motivation to seek out food variety has the clear advantage of helping to obtain a sufficiently wide variety of nutrients that are needed for healthy living (Epstein, et al., 2009). But behavior that was adaptive in conditions of food scarcity can be a risk for overeating in an environment filled with varied energy-dense foods (e.g., several flavors of salty snacks, cookies, candies, ice cream, and sodas).

If variety increases intake of less healthy foods, it may also increase intake of healthier foods. Children provided a variety of healthier foods increased energy intake for health foods. Overweight people who enter weight control programs are more successful if they reduce the variety of high energy density foods they consume (Epstein et al., 2015). Thus, it may be possible to take advantage of food variety to improve healthy eating while simultaneously reducing access to a variety of less healthy alternatives.

Reference:

Epstein, L. H., Temple, J. L., Roemmich, J. N., and Bouton, M. E. (2009). Habituation as a determinant of human food intake. Psychol. Rev. 116, 384–407.

Epstein LH et al., (2015) Reducing variety enhances effectiveness of family-based treatment for pediatric obesity Eat Behav. 2015 Apr; 17: 140–143.

Johnson F, Wardle J. Variety, palatability and obesity. Adv Nutr 2014;5:851–859.

Just, D. R. and Wansink, B. (2011) The flat-rate pricing paradox: conflicting effects of ‘all-you-can-eat’ buffet pricing, Review of Economics and Statistics,93, 193–200.

Rolls, B. J., Rowe, E. A., & Rolls, E. T. (1982). How sensory properties of foods affect human 614 feeding behavior. Physiology & Behavior, 29 (3), 409-417.

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Raynor H, Epstein L. Dietary Variety, Energy Regulation, and Obesity. Psychological Bulletin 2001; 127: 325-341.