Washington State University

Ask Dr. Universe

Yes, you are what you eat. Kind of.

January 6th, 2012

Dear Dr. Universe,
Why do people like different foods?
Nicole Ruslim
Melbourne, Australia

Fudge from Seattle's Fat Cat Fudge. by Matt Hagen

Fudge from Seattle's Fat Cat Fudge. by Matt Hagen

This is one of those very complicated questions that require a lot of experimentation. So let’s do some research on whether you and I like the same foods or not!

Seriously, lots of scientists are also interested in this question. Bob and Sue Ritter here at Washington State University have studied forms of this question for much of their careers. Sue Ritter studies appetite, or what makes us start eating. Bob Ritter studies satiation, or what makes us stop eating.

When I went to visit with the Professors Ritter, I just happened to have a bag of pretzels with me. Professor (Sue) Ritter admitted that they looked pretty good to her. It was late afternoon, and she hadn’t eaten since breakfast. Her blood glucose—a sugar that the body uses to store energy and then release it when needed—was getting pretty low. Pretzels are high in carbohydrates, which change to glucose during digestion.

Professor Ritter was also hungry for salt, which our bodies need. The sodium and chloride in salt, along with potassium, are ELECTROLYTES. Electrolytes help the kidneys manage the body’s fluid levels. Salt is also necessary for the “action potentials” that make your brain and nervous system work.

In general, when you get hungry, your body is signaling you that you need some energy. Your body has different “receptors” in the brain and other organs that tell you, I’M HUNGRY whenever they need energy. These receptors also look for specific nutrients. When they figure you’ve had enough, they send signals to the brain to shut off the energy alert.

The brain in particular says “AND I NEED IT RIGHT NOW!” Think about it. Your brain is running your whole show, which takes a LOT of energy. Even when the rest of the body is satisfied, the brain might need more energy. In fact, says Professor (Sue) Ritter, we may overeat sometimes because our brains still need energy.

And how exactly does the brain get this energy? From glucose. Glucose is the only energy source that can pass through your blood-brain barrier, which is a filter that keeps toxins away from your brain.

This does not mean, however, that every time your brain feels a little tired, you should wolf down three candy bars. There are plenty of better ways to get glucose. Fruit is a good one. Also, the brain can store only a little bit of reserve energy. If your brain doesn’t need the extra energy at the moment, and neither does the rest of your body, where’s that extra “energy” going to go? FAT!

So, to some extent, your taste for different foods is your body’s way of telling you what it needs. Maybe on Tuesday, your body feels a little low on Vitamin A. So you eat something with a taste that your body knows has provided Vitamin A in the past—carrots, maybe. Or you need some protein. So you munch a bag of nuts. That’s okay.

But just because you want salty, fatty chips doesn’t mean your body NEEDS fat. In other words, just because you’re hungry for fat doesn’t always mean you need it.

In fact, Professor (Bob) Ritter and his colleague Mihai Covasa believe that a lot of us have become IMMUNE or insensitive to fat. Their experiments suggest that if all you eat is chips and fast food, which tend to be very high in fat, eventually your body’s “I’m full” signals quit working properly.

And eventually you become what you eat. You become … fat.

I also visited Mary Watrous in the history department here at WSU. She studies the role of food in different cultures and how women carry on food traditions. She says that people like specific foods because that’s what everyone else in their culture eats. Seems obvious, right? But think about it. Food can have different meanings. Maybe you like a certain food because your grandma makes it for you, and she likes it because her grandma made it for her. Or you might like a food, and dislike others, because it has special meaning in your religion.

People also differ in HOW they taste certain foods. Some people have genes that make them SUPERTASTERS. Supertasters taste certain bitter compounds in foods (such as in Brussels sprouts) that other people don’t notice.

Also, your taste may change as you grow up. Is there something that your mom loves, but you hate? She probably thinks that you’re just being persnickety. “Just try it, you’ll like it,” right?

But according to Adam Drewnowski, who studies nutrition at the University of Washington, maybe it really DOES taste awful to you. Explain very politely to your mother that you’ve been doing some research, and that you’ve learned that maybe your taste buds haven’t matured like hers. You might even compromise and suggest that even though the broccoli tastes bitter to you, it might not taste so bad if she put a little cheese sauce on it.

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