Why Calories Taste Delicious: Eating and the Brain
There are two main neurological mechanisms that manage food intake: one controls the need to eat and the other controls the desire to eat. Because the hypothalamus in the brain monitors the homeostatic control of food intake by collecting, organizing, and responding to metabolic signals from the digestive system, it tells us when we need to eat. The dopamine reward system is a brain center that becomes excited when you eat something you want but do not need to suppress hunger. Many times the desire to eat can overpower the need to eat, so people will eat food that tastes good even when they are not hungry. The hypothalamus regulates intake based on metabolic value. When you are hungry, your body looks for food with a multitude of calories.
Researchers used a line of mice genetically engineered to lack a receptor for distinguishing sweetness, so if these mice prefer sweetness it is because of the larger amount of calories. In the first set of experiments, the genetically altered mice were indifferent to sucrose, table sugar, and the mice with no mutation strongly preferred the sucrose over the water. In the second set of experiment, both mice were given access to water and sucrose for six days. The genetically altered mice couldn't taste the sweetness, but they learned to like it more. Even without the receptor, the mice seemed to feel something enjoyable about eating the sweet food.
Both experiments were then repeated with sucralose, Splenda, in the place of sucrose. The mice without the mutation still consumed more Splenda than they did water, but the genetically altered mice did not. These results show the genetically altered mice preferred sucrose for the calories not the sweetness and that being able to sense metabolic value can affect feeding behavior. Although dopamine was increased in the mice without mutations with both sucrose and sucralose, the genetically altered mice were only affected by the sucralose. While the dopamine reward system responds to sweet taste, it may also be involved in monitoring calories.
My response:
While I have always known that sweeter food has more calories, I have never thought about how our bodies need those calories. I found it interesting that the genetically altered mice preferred the sweeter food even when they could not taste the sweetness. I also think that taste must still determine it more because the mice without the mutation preferred the Splenda over the water. I wonder how much this plays in contributing to obesity.
posted by Sarah @ 1:29 PM
3 Comments:
I think that it would be interesting and informative to alter the experiments involving the mice to include a sweet food and a less sweet or more bland food with the same amount of calories. Would the genetically altered mice still prefer a food with a sweeter taste over another which, although less sweet, contains the same amount of calories?
I also think that the information in this article does play a part in eating disorders, like over-eating which can lead to obesity. Too often people seems to get the two mechanisms controlling food intake confused. With the abundance of sweet and good tasting foods available, people are more likely to misinterpret a desire to eat as hunger. Marketing and advertisement in American society have taken advantage of this confusion and, I think, added to it.
It is very interesting that the mice with the mutation chose the sweet food over the water. I wonder, what would happen if they put a sweet food with zero calories and a tasteless food with an abundance of calories, would the mutated mice eat the food with more calories still? Also I do not believe that this information will affect the rising rate of obesity because, though things with higher calories are more appealing, is there a way to trick the body into thinking that it is getting more calories than it is? Otherwise there is no way to get the same satisfaction from eating something with no calories, that there is from something with many calories... And finally I think this may be why people love Chipotle...there is nothing like 1200-1400 calories in one sitting obviously.
This article is very interesting because I always believed that people who always craved sugar just had a sweet tooth. Although in most situations this is the case, this article opened my mind to thinking that people who eat lots of sugar may just desperatly need the calories.It was very interesting how the altered mice ate sucrose but rejected the splenda. This shows that in our senses or instinct we are natirally able to identify what is good and what is bad for us. With this information I believe it would be interesting to see what would happen to a persons health if we were able to shut down their desire for food and just leave the need. Could this cure obesity or even eating disorders?
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