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Ask Dr. Mike: Can Junk Food Rewire Your Brain?

Here you'll find the answers to a wealth of health and wellness questions posed by Healthy Talk fans. Listen in because what you know helps ensure healthy choices you can live with. Today on Healthy Talk, you wanted to know:

Junk food rewired people's brains. Can you shed some light on this?

Published in Journal Frontiers in Psychology, a new study shines some light on the possibility that junk food has the power to rewire your brain. Scientists put rats into two groups; labeled Cafeteria and Chow. Both rats had a typical rat diet, but the Cafeteria group got bonus foods that included meat pies, cookies, and cakes.

Researchers found that both rat groups gained weight, but the Cafeteria group gained more weight and didn't seem to care about balancing their diet. Researchers believe that the junk food diets of today cause lasting changes in the reward circuit part of the brain, which also plays a major role in decision-making.

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RadioMD Presents:Healthy Talk | Original Air Date: May 6, 2015
Host: Michael Smith, MD

You're listening to RadioMD. It's time to ask Dr. Mike on Healthy Talk. Call or email to ask your questions now. Email: This email address is being protected from spambots. You need JavaScript enabled to view it. or call: 877-711-5211. The lines are open.

DR MIKE: So, Allen sent me an e-mail. Allen is a long time listener, he says. Thank you, Allen. He wrote:
"Life Extension posted a blog on how to junk food and rewires our brains. This would be a great article for you to review on your show. Thanks, Alan."
So, it's not really a question but I think this, obviously, resonated with Allen. He found this interesting. So, I went back and looked at our blog. You can check it out at and, of course, my good friend May Lynn Pas, who I've talked about before, she writes for my show.

She writes articles and blogs for Life Extension. She works in the social media department. She's a registered nurse, so if you want to go check that out, again, that's

Now, so the title of this was, "Junk Food Rewires Our Brains," and it looks like it comes from some research that was published in the journal Frontiers in Psychology from August of last year, 2014, and now May Lynn begins by writing, "If you find that you are not inclined towards healthy foods, don't be so hard on yourself. It may not be just a lack of willpower, discipline or motivation, after all. In fact, a new study shows that junk food can actually rewire the brains of rats, at least, to increase their preferences for junk food."

Hey, don't forget the rat is a good model for humans. It's true. Our physiology is very similar to the rat, especially the white rat or the white mouse. Very, very physiologically similar to humans. So, if something happens in the rat, it most likely does extrapolate to the human, but we always have to put that disclaimer in there. So, the first thing that May Lynn writes here, Allen, let's see. Rats...and I haven't reviewed this. I didn't see this.

I'm going over this just right now with my listeners. "Rats fed junk food avoid balanced diets", so they just keep craving the bad stuff and you keep eating the bad stuff, right? Researchers from –so, this came from researchers in Australia--and again they published in Frontiers in Psychology, wanted to test the effect of junk food on weight and food preferences. They assigned rats and one of two diets with the difference being the inclusion of meat, pies, cakes and cookies in one group. That made me hungry. Weight gain was seen for both groups. Okay.

So, basically these rats were, it looks like, put into two groups and they didn't really limit what they were eating, except there was some more junk food in one group. Now, both groups of rats gained weight but the group, obviously, eating the junk food gained about 10% more. Okay. That's not that hard to see, right? Both groups were trained to associate flavored waters, cherry and grape, to two different sounds each time a specific sound was played.

So, this is after. After they got used to these diets. Okay? So, you have two groups of rats. They're eating the same amount but one group is eating some more junkie food and they gained about 10% more, right? Now, here's what they did. Now, so you've got these two groups of rats eating these two different diets. Both groups of rats were trained, now, to associate flavored waters to two different sounds. Each time a specific sound was played, it was a cue for the rats to drink a specific flavor. The group eating the more healthy diet responded correctly to the sound cues. After drinking grape water, for example, they would ignore the sound cue to continue drinking grape water. So, they had some control in all this. On the other hand, the rats that were in the junk food group would drink the grape water, they'd hear the sound and they just kept right on drinking the grape water.

They didn't care. They, basically, stopped listening to the researchers. The same reaction was observed with cherry water, which, basically, grape water, cherry, this is just all sugar. So, you know, the rats on the healthier diet, which, they didn't gain that much weight, they had a better control over not overindulging, if you will.

They listened to the sound and the researchers and they were able to stop drinking the sugar water, basically. The rats that had some of the junk food ate it and they gained more weight, they lost all control. After two weeks, it was apparent that the group eating the junk food, they were not interested in a balanced diet which encourages us to seek novel foods. They resumed their normal diet. They continued to seek out the junk food given to them during the study and they drank the flavored waters indiscriminately. Does that sound like some humans you know? Okay. Listen, it makes sense.

Now, they go on to say. What's going on here, why...So, why would these rats who are given the meat, pies, cakes and the cookies, why would they just decide not to even search out healthier food? "Just let me stick with this junk food." Why would they do that? Why would they overindulge? The authors propose, based on results from other published studies, that rats from the junk food group, changes occurred in the reward section of the brain which controls decision making. This could explain why they overindulged in junk food. Hmm. So, there is, there's like a change. There are parts of your brain that are based on reward so you can do behaviors that keep you surviving longer.

There's a reward mechanism in the brain, so we avoid behaviors that could kill us and we do behaviors that would keep us alive. That's why eating food is sometimes comforting to us because we've got to stay alive and bring in energy, but that has to be controlled. Those reward centers in the brain are...There's feedback mechanisms that shut them off so we don't overindulge where it looks like when you eat a lot of junk food, at least in rats, the control mechanism on the reward parts of the brain shut off and they just wanted to keep getting that reward. So, it was a rewiring of the control mechanism that kind of shuts off those reward parts of the brain. So, when that mechanism is shut off, you're just constantly activating that reward part of the brain and you just want to keep eating the meat, pies, cakes and cookies. Hmmm. And, again, the rat brain is very, very similar to the human brain.

By the way, the authors go on to say hard drugs such as cocaine produce similar changes in the brain. With continual use, a greater quantity is needed to produce a desired high. The same relationship has been seen with junk food.

So, is junk food the new cocaine? Bottom line: the study was conducted on rats, but it may offer insight as to why many humans tend to overindulge in junk foods. In a day and age when junk food is so common, it can be hard or even, in some cases, impossible to resist. So, how do you do that, though? I mean, if you do feel like you're somebody who is a little addicted to junk food and it's hard to break that, especially when you're stressed, for instance. How do you do that? How do you, you know, wire the brain back to normal so that you can bring down those reward mechanisms in the brain? You know, to inhibit them a little bit.

Well, it just takes more willpower. I mean, it does. I mean, breaking addictions, whether it's junk food or cocaine, at some point, you have to eliminate it and you have to overcome that desire to put it back in by controlling the reward behavior. That's what a lot of addiction programs are based on.

So, one of my favorite ways of doing this is called the "first line thought process". Have you ever heard of this? I don't know if that's the formal name for it. It's the front line or first line thought process. You simply tell yourself "no". The minute you think about, "I want that Twinkie." "No." It's almost like you're talking to yourself like a child. You want that cigarette? "No." Walk away. You act like you...You almost treat yourself like a child. You want that Twinkie? "No." It's first...So, when that thought comes in to overindulge in that bad thing that's gotten you fat and, you know, gotten you in trouble? Drug or food, it doesn't really matter. You tell yourself "no".

It's reestablishing the normal inhibition on the reward part of the brain. Try it. I don't know. It may work for you.

There you go. Junk food rewires our brains. Or, at least, rat brains. Hmm.

This is Healthy Talk on RadioMD. I'm Dr. Mike. Stay well.