The Second Stomach for Dessert

Sensory-specific satiety, a behavior that originally developed to regulate humans’ eating habits, is now the driving force behind our second stomach for dessert.

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By Tina Siu

If you’ve ever found yourself guilty of not finishing dinner, yet feeling hungry for dessert, you’re not alone. Many people relate to the experience of having a “second stomach” for dessert. Why is it that you can finish half a pint of Ben and Jerry’s ice cream when you thought you couldn’t fit even one more bite in after dinner? Studies show that humans might actually have a second “psychological” stomach for dessert.

One of the main factors that contributes to how much we consume is the variety of foods available. The larger the variety of food, the more we consume. When humans are exposed to the same stimulus over and over again, they face habituation—getting sick of things. Habituation is a decrease in the response to a stimulus and can be described as food no longer tasting good or getting tired of eating. Among other things, it helps us terminate eating. Habituation theory states that the presentation of a new food acts as stimuli to delay satiation, or the state where needs and desires are filled to a point of excess, not just satisfaction. This varied food effect can be attributed to sensory-specific satiety, which is a decrease in appetite for food already eaten relative to non-consumed foods with different sensory qualities, such as taste, texture, and appearance. For instance, if you’ve already had a satisfying meal of vodka pasta, you would be more likely to reach for a helping of chocolate pie, a new food with different sensory qualities, rather than another spoonful of pasta.

A study conducted by the University of Oxford looked at the responsiveness of ventral forebrain neurons in monkeys in relation to sensory-specific satiety. When the monkeys were presented with food that they had already eaten to satiety, the response of hypothalamic neurons to the sight and taste of the food decreased. However, when the monkeys were presented with food they were not satiated by, the response of the hypothalamic neurons remained unchanged. This suggests that the responses of the neurons in the ventral forebrain are related to and support the theory of sensory-specific satiety.

From an evolutionary perspective, sensory-specific satiety developed to encourage humans to seek out a variety of foods to obtain the necessary amount of nutrients for the body. However, this behavior was nurtured in environments where food was scarce and can now be a risk in current environments filled with varied energy-dense foods like salty snacks, cookies, and candies. Instead of falling prey to sensory-specific satiety, however, humans can take advantage of it to achieve health and weight loss goals. A study showed that children provided with a variety of healthier foods increased their intake of these foods. Additionally, people who enter weight control programs tend to be more successful if they reduce the variety, and thus consumption, of energy-dense foods.

Though sensory-specific satiety originally evolved to regulate eating habits, it now poses a potential health risk to humans, so it’s important to be mindful of what you consume. Remember that there is a difference between being full and feeling satiated, and that difference is controlled by your mind. Nutritionists suggest that the best way to control your second stomach is to carefully observe your satiation levels. If you would not be able to fit in another bite of a nutritious dinner, then you probably shouldn’t be eating dessert. That being said, it’s okay to take advantage of your second stomach every once in a while to eat that cheesecake you’ve always wanted to try.