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Why Does Fat Taste So Good?

The importance of fat-tasting proteins on the tongue

One of the best things about the taste of milk chocolate is its wonderful creamy smoothness. That feeling is due to the presence of fat. In spite of this universal feeling that fatty foods produce on the tongue, scientists have always claimed that we do not actually possess the ability to taste fat. The textbooks only mention our ability to taste sour, salty, sweet, bitter and, rather recently, umami (which is the taste produce by the additive MSG). A recent study published in the Journal of Lipid Research by Pepino et al., claims that humans, and other animals, exhibit a protein on their tongue that can sense the presence of fat. If there is a protein for tasting fat then there must be a gene responsible for this protein. Indeed, this gene has been identified, and it appears as though variations in this gene explain why some people are far more sensitive to fat in their food than are other people. What does this mean for treating obesity and controlling our eating behavior?

I was recently honored by an invitation to give a TED talk on this idea. The video is available here.

The amount of this fat-tasting protein on the tongue varies. If you've inherited a tendency to have fewer of these receptors, then your response to fat is muted and you are more likely to be obese. Obese people do prefer food with higher fat content and consume fat as a larger percentage of their overall calorie intake. Even if you have not inherited this tendency, if you consume lots of fatty foods you will modify the activity of this gene and subsequently make less of the fat-tasting protein. Unfortunately, as a consequence you become less sensitive to the taste of fat and begin to prefer foods that contain higher levels of fat in order to obtain the same pleasurable sensation when eating. Essentially, you start eating more fatty foods but enjoy them much less. Consuming fat appears to be linked with the ability to metabolize it. Rats that have been genetically altered to lack this fat-tasting protein do not enjoy the taste of fatty foods and have a problem digesting it.

What if you decided to fool your taste buds with a fat substitute? A recent study by Swithers et al., in Behavioral Neuroscience, discovered that the taste of fat on the tongue might be enough to trigger the body to inappropriately metabolize all the calories you consume. Rats that ate a diet that contained a mixture of real fat and fat substitute actually gained more weight and developed more fatty tissues than rats that only consumed real fat. The overall message of these studies is that our bodies have evolved a sophisticated system for monitoring the content of fat in our mouths and gut and that this system can be altered by what we choose to eat. Therefore, if you choose to consume fatty foods, try to limit the amount as much as possible; however, never attempt to fool Mother Nature by using fat-substitutes; your tongue will know the difference.

© Gary L. Wenk, Ph.D. author of Your Brain on Food (Oxford, 2010)

See also: "Why Marijuana and Coffee are good for the brain"

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