Marshmallows, lollipops, gummi bears -- we want them all! But we’ve all heard that eating a lot of sugar isn’t that healthy for us. So what’s the deal? Why do we like sugar so much in the first place? We’ll find out why our bodies evolved to seek out sweet things, and how clever humans invented a way to make food even sweeter. And we’ll get to the bottom of a confectionary conundrum from our co-host Zoe: are sugar rushes a real thing? Plus: Sanden cooks up some very sweet schemes and we have a new mystery sound for you to guess!

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ZOE: You're listening to Brains On where we're serious about being curious.

BEN: Brains On is supported in part by a grant from the National Science Foundation.

SANDEN TOTTEN: Quick, Penelope. Bring me the syringes.


Excellent. Now the shakers.


I don't know. I guess all of them. Look, we're running out of time.


Good. Good. Now, the final step, the infuser master 3,000.


I know it's dangerous. I invented it, Penelope.


Well, I didn't make it dangerous on purpose.


The risks are worth the rewards, Penelope. We're going to change the world as we know it with this invention. We have to press on.


Oh, yeah. No, we should totally put our safety goggles on first though. Good call. Now, let's do it. Let's turn on the infuser master 3,000. Here we go. Whoa. It worked. Penelope, we did it. It's alive. It's alive.


No, you're right. It's not alive. I'm sorry. I just wanted to say that. It sounds so cool. Still, they said it was impossible. They laughed at my kickstarter campaign. They said things like, Sanden, this is going too far. Sanden, you still owe me $3.


I said I'd pay you Thursday, Penelope. Stop ruining my moment. Jeez.

They said I was mad, but who's mad now? Because my invention worked. I've created the world's first sugar-frosted, sugar-coated, sugar-infused vegetables. Ha-ha-ha. Welcome to the age of sweet salads, caramel carrots, honeyed habaneros, and sugary spinach. Ha-ha-ha. Now, all that's left is to taste it.


It's terrible.


Well, I'm not going to throw it out. The taste grows on you the more you eat it.


No, I was lying. It's still terrible. It's actually getting worse the more I eat it.


I don't know. I just can't stop.


No, you can't have any though. It's important I eat all of them. I don't know why. Well, because I invented it, and your dog.


Stop barking at me like that.


This is awful.


MOLLY BLOOM: You're listening to Brains On from APM Studios. I'm Molly Bloom, and my co-host today is Zoe from Philadelphia. Hey, Zoe.

ZOE: Hi, Molly.

MOLLY BLOOM: Zoe, you wrote us with a very sweet question.

ZOE: Yeah, I wanted to know if sugar rush is a real or not.

MOLLY BLOOM: Zoe, what inspired this question about sugar rushes?

ZOE: Well, at school before the pandemic started, everybody always went really crazy after. We had a sweet treat or something so I just started wondering.

MOLLY BLOOM: I remember in your question that you originally sent us, you said like "My parents told me they're not real." What is one piece of information that makes you think it is real?

ZOE: The fact that my classmates are bouncing off the desks.

MOLLY BLOOM: And then what's another piece of information that makes you think it's possible it might not be real?

ZOE: The fact that not everybody gets them.

MOLLY BLOOM: Very good. Do you have a favorite form of sugar?

ZOE: Mint chocolate, peanut butter chocolate, Skittles, M&M's. Just about every kind of sweet that exists. I have never met anything that involves sugar that I do not like.

MOLLY BLOOM: It is very delicious. And you're not the only one curious about sugar. These listeners have some questions too.

CHARLIE: Hi, my name is Charlie and I live in Cleveland, Ohio. And my question is, why is sugar so delicious?

JASPER: Hello, my name is Jasper and I live in Portland, Oregon. And my question is, what is sugar made of?

AIDAN: My name is Aidan from Oakland, California.

AMELIA: My name is Amelia and I'm from Fredericton, New Brunswick.

AIDAN: My question is.

AMELIA: My question is.

BOTH (AMELIA AND AIDAN): Why do people like sugar so much?

AIDAN: My name is Aidan. I'm from Winter Park, Florida. And my question is, how does sugar make you hyper?

MIMI: Hi, my name is Mimi from Chicago, Illinois. And my question is, why does sugar make you hyper? I was thinking about this question why so much candy at night and couldn't fall asleep.

MOLLY BLOOM: Thanks to Charlie, Jasper, Aidan, Amelia, Aidan and Mimi for sending us those questions about sugar.

SANDEN TOTTEN: Did somebody say sugar?

ZOE: Oh, hey Sanden.

MOLLY BLOOM: Sanden, what are you doing here?

SANDEN TOTTEN: Well, I overheard you talking about sugar rushes. And it just so happens that is exactly what I'm after.

MOLLY BLOOM: I feel a Sanden scheme coming on.

SANDEN TOTTEN: Molly, it's not a scheme. It's called a strategy. You see I need a sugar rush so I can start building my next great invention. The supersonic sweet stash-omatic. A super stealthy machine that will find the best hiding spots and stash all of my candy in the best secret spaces.

It's basically a box with creepy metal spider legs that will get up and crawl to a new hiding spot every 24 hours. That way, no one, not Marc, not Gungador, not even elevator will be able to find my collection of candy and confections. But first, I need some extra energy.

ZOE: I don't know, Sanden. It seems that you already have lots of energy.

SANDEN TOTTEN: Oh, I do. But if I'm going to build this supersonic sweet stash-omatic, I'm going to need all the energy I can get. I mean, just saying the name is a workout. Why did I make it so long? I don't know. Plus we're talking about sugar. Come on. Don't you just want to eat something sweet and delicious? Here's the game plan.

I'm going to start strong with some super fruity Num Noms cereal, like maybe one bowl or six. Follow it up with a couple of spoonfuls of molasses, scrumptious, maybe throw in a candy necklace just to be safe.

MOLLY BLOOM: OK, a little bit of sugar is OK, but this sounds like overkill.

ZOE: Yeah, we're worried about you Sanden. We want you to get a stomach ache.

SANDEN TOTTEN: Whoa, whoa, whoa, whoa. Here's the thing. Your body actually needs sugar. Just listen to my friend Monica Dus. She's a professor of biology at the University of Michigan and she studies how sugar affects the brain.

MONICA DUS: Hey, Sanden.

SANDEN TOTTEN: Hi, Monica. I was just telling everyone here about how our bodies need sugar. Isn't that right?

MONICA DUS: Yeah, so all our cells need fuel to survive. Not just because they burn it as energy, but also because they use parts of the food we eat as essentially building blocks or bricks to build cells or different structures like hair or skin. Our cells really love sugar because they can burn it really fast. And so they can utilize it almost immediately. That's why it's one of the best form of energy.

SANDEN TOTTEN: OK, did you catch that? Sugar is one of the best forms of energy. It helps our cells build and grow and gives them energy fast.

MONICA DUS: Let's think about the most common way to think about sugar which is the white crystal substance in the food packets at restaurants or coffee shops or in your kitchen cupboards.

SANDEN TOTTEN: Or in super fruity Num Noms cereal. Num Noms.

MONICA DUS: That sugar, it's known as sucrose and it's made of two different building blocks of sugar. Glucose and fructose. When we eat that sugar, our body breaks it down. And then those two glucose and fructose are actually take different paths in our body and so are seen in different ways. For example, the glucose goes into our bloodstream and then reaches the brain, and then it helps tell the brain that what we're eating has energy and so it's a very good positive feedback.

SANDEN TOTTEN: The glucose breaks down, goes into our bloodstream, and not only does it tell our brains it's eating a sweet, it also delivers that sweet, sweet energy to our cells. Let's get the old zoom ray out and see how those cells are doing.

Wow. Look at those cells go. They are hyped.

GLUCOSE: Glucose doing the glucomost.

SANDEN TOTTEN: Oh, yeah. And like Monica said, that glucose also makes its way to the brain, which starts releasing this chemical called dopamine. The dopamine makes us feel really happy.

BRAIN: I am the brain and I feel sweet. Dopamine. Dynamite.

ZOE: And what happens to that other building block Monica mentioned? Not the glucose but the fructose.

SANDEN TOTTEN: Oh, yeah, that does something different.

MONICA DUS: The fructose doesn't reach our brain. The fructose go to different organs in the body to the liver. And in the liver, the fructose is turned into other kinds of molecules. One of them is like a type of fat.

LIVER: I'm the liver and I'm going to take this fructose and turn it into fat. That way, we can store more energy for later.

SANDEN TOTTEN: I'm going to need that energy to build this supersonic sweet stash-omatic. See, ta-da our bodies need sugar. That's why we like it. That's why it's the best. The end of episode. Goodbye. Let's roll the credits. See you all. Thanks for coming.

ZOE: But the sugar you're thinking of: the candies and bacon and candy and all that. That's not the kind of sugar we were eating as humans evolved.

SANDEN TOTTEN: Too bad for them. But so what? Sugar is sugar.

MOLLY BLOOM: You're right. When our cells process sugar no matter where it comes from, it's the same process.

ZOE: Honey, maple syrup, starch just like bread, sugar, sugar.

MOLLY BLOOM: But, and this is an important but.

SANDEN TOTTEN: Really? No one's going to comment on that?

MOLLY BLOOM: For most of human history, we didn't eat anywhere as much sugar as we do today.

ZOE: Lucky for us, we have a friend here to help us explain.

KEN CALDEIRA: I'm Ken Caldeira at the University of the Pacific in Stockton, California. I'm a food historian.

MOLLY BLOOM: Ken, what kind of sweet things did our ancestors eat?

KEN CALDEIRA: Well, there wasn't a whole lot that was sweet in nature that they could access, mostly fruit. Sweetness is calories and that's why we're hardwired to like it.

ZOE: You know carrots, right Sanden?

SANDEN TOTTEN: Yeah. They're adorable.

ZOE: Well, back in the day, they were seen as sweet.

SANDEN TOTTEN: I love carrots, but they are not dessert.

MOLLY BLOOM: But they do have sucrose and glucose in them just like white baking sugar. But foods like carrots also have lots of other stuff in them too. Things like fiber and vitamins and starches. Starches are sugars too, but they're multiple sugars stuck together so it takes your body longer to break them down.

ZOE: That means the energy you get from those sugars is released more steadily over a longer period of time.

MOLLY BLOOM: But eventually, we figured out ways to separate the sugar found in plants from all the other plant stuff in there.

SANDEN TOTTEN: Which clever humans did that? I'd like to personally thank them.

KEN CALDEIRA: Well, getting sweeter things has a lot to do with partly travel and movement of plants and partly discovery of ways to concentrate that sugar. In the case of sugar cane, very few people had access to it because it comes from New Guinea.

ZOE: Sugar cane is actually a kind of grass. It looks a bit like bamboo. And inside is loads of sucrose and water and not much else.

KEN CALDEIRA: It was literally just isolated and people there, of course, chewed on it. But figuring out a way to press out the juice and then to evaporate it over a fire and then to refine it, all those are different stages. So there's really nothing like sugar in nature that's that concentrated sweetness.

MOLLY BLOOM: Right. The juice of sugar cane tastes like the sugar we use for baking and such, but it's not as powerful as sweetness. But to get little crystals of pure sugar, you'd have to find a way to take just the sugary stuff from the plant and make it its own thing.

ZOE: The first place that figured out how to do that, to concentrate and refined that sugar cane into just sugar was in India.

SANDEN TOTTEN: High fives, India.

ZOE: That process is at least 2,000 years old, and that first kind of refined sugar is still in today.

MOLLY BLOOM: It's called jaggery. It's brown, usually comes in little cones and is, of course, delicious.

ZOE: But they weren't using it to make cotton candy and super sweet treats.

KEN CALDEIRA: Think of sugar as a spice, that's really its primary role. In India and then in medieval Muslim cuisine, Chinese cuisine and South East Asian cuisine, it's all over the place.

MOLLY BLOOM: Humans also figured out ways to separate out sugar from other sweet plants like sugar beets and corn.

ZOE: And today, sugar is in a lot of the foods we eat. Not just what you think of the sweets.

MOLLY BLOOM: If you get a fast food hamburger, say.

KEN CALDEIRA: Every single thing, every ingredient has sugar in it in some form or another. The ketchup especially is tons of it. But even the bread, even the meat sometimes is sweetened, because we like sugar.

Manufacturers figure if we can just take sugar in some form, put it in food people will like it more, we'll sell more of that product and we'll be making money. I don't think it's on people's radar. How much sugar we're actually taking in? And that it is essentially non-nutritive. It doesn't have-- it gives you calories, but there's no other benefit from it.

ZOE: Sugar gives you energy, but no vitamins or fiber or any of the other things your body needs.

MOLLY BLOOM: And if you eat a lot of sugar.

ZOE: Sanden.

KEN CALDEIRA: Your body gets used to it. And if you eat sugar on a regular basis and you suddenly stop, you notice it.

MOLLY BLOOM: You might feel a little crabby, maybe a little tired, because your body is used to getting that quick influx of calories and energy and dopamine. But after a little while if you eat less of that pure sugar, your body will adjust and you won't miss it as much.

ZOE: Your sense of taste will adapt, too. After a while, you'll be able to pick up a natural sweetness better. The same thing can happen with other strong flavors like chili or salt.

KEN CALDEIRA: If you ever use like a Boolean cube or canned broth, it's really, really salty. I mean, and if you make a broth at home, it's just seems flat or something's missing. And if you keep using the homemade for after a couple of weeks, you taste it and all of a sudden you taste carrots and celery and bailey even things that you just don't get in the cube.

SANDEN TOTTEN: So you're saying I should try to eat less sugar?

MOLLY BLOOM: Everything in moderation.

SANDEN TOTTEN: Wait, hey, if I eat less candy, then carrots I'll start tasting sweeter like candy.

ZOE: That's one way to look at it.

SANDEN TOTTEN: Carrot candy, here I come.

MOLLY BLOOM: Thanks for your help, Ken.

KEN CALDEIRA: Lovely. Take care.


MOLLY BLOOM: OK, Zoe. I have a sweet treat for your ears. It's time for the?

ZOE: Mystery sound.

MOLLY BLOOM: Here it is.


Zoe, what did you hear there?

ZOE: Something scraping maybe.

MOLLY BLOOM: What might be the thing scraping? Do you have any ideas?

ZOE: I don't know. Maybe like a knife. Maybe like a knife over a cutting board or being sharpened or something.

MOLLY BLOOM: Oh, very good guess. Well, we're going to give you another chance to guess and reveal the answer right after our episode credits.


We're working on an episode right now about long journeys and we need your help. If you were walking around the world, what is one place you'd definitely want to make sure you saw? Is it the pyramids in Egypt? Maybe the glow worm caves in New Zealand? Or perhaps it's the lovely rolling hills of Western Wisconsin? Zoe, what's one place you'd want to make sure you saw?

ZOE: That place in China or maybe India where there are all those colorful buildings. Taj Mahal.

MOLLY BLOOM: Oh, Taj Mahal. Yeah, that's in India. Very cool. That's a beautiful place. Listeners, send us your answer at Speaking of trips around the world, you can head to our website and pre-order our brand new book. It's called Road Trip Earth.

ZOE: It's a super fun journey from the center of the Earth to the outer atmosphere.

MOLLY BLOOM: It's chock full of facts and comics and we think you'll love it.

ZOE: You can pre-order Road Trip Earth at

MOLLY BLOOM: And if you have any drawings you want to share with us or mystery sounds or questions, you can send all those to us at our website

ZOE: That's where we got this question.

Hi, my name is Alex from San Antonio, Texas. My question is, do we have our own gravity, like how the Earth pulls stuff toward it?

MOLLY BLOOM: To hear the answer to that question, find our brand new Moment of Um feed wherever you get your podcasts.

ZOE: That's right. Search for a Moment of Um and your favorite podcast player.

MOLLY BLOOM: Thanks and keep listening.

ZOE: You're listening to Brains On from APM Studios. I'm Zoe.

MOLLY BLOOM: And I'm Molly.

SANDEN TOTTEN: And I'm Sanden. And I'm also having a sugar rush.

ZOE: Wait, didn't you just tell us you were going to cut back on your candy intake?


MOLLY BLOOM: So why are you and Penelope currently playing hopscotch on our couch cushions?

SANDEN TOTTEN: Penelope has the zoomies, and I have a sugar rush. You see I wanted to make sure that I'd have no candy to tempt me so I got rid of all of it by eating it.

MOLLY BLOOM: Oh, dear. But Zoe is not sure if sugar rushes are really real.

SANDEN TOTTEN: Well, I know for sure that sugar rushes are real. Why else would I be up here hanging from the chandelier? Hoo ha-ha-ha.

ZOE: It's pretty impressive how he trained Penelope to sit on his shoulders like that.

MOLLY BLOOM: Sanden, get down from there. You could hurt yourselves.

SANDEN TOTTEN: No problem. I'll just jump down. Land on this trampoline. And keep jumping. Woo. Woo. Woo-hoo. Ha-ha. This is so fun.


MOLLY BLOOM: It's our pal Kathryn Sundquist.

KATHRYN SUNDQUIST: I looked into your question about sugar rushes and I found the answer. The idea that eating a bunch of sugar at once will make you super energetic is-- drum roll, please?


KATHRYN SUNDQUIST: Thanks, Sanden. It's simply not true.

SANDEN TOTTEN: What? No way. I just learned that my body uses sugar for energy. And I just ate a lot of sugar and I am so excited. I mean, just look at me dance. I'm doing the dance, move my feet, everything's great when you eat less sweets.

KATHRYN SUNDQUIST: Well, it's true that sugar gets turned into energy but our bodies don't use all of the sugar at once. When you eat something with a lot of sugar, only a little bit gets used right away and the rest is stored away for later. Your body works very hard to keep the amount of sugar in your body steady. Not too much and not too little. So even if you eat an entire bag of candy, your body will only use some of that sugar for energy right away. It shouldn't make you act bananas.

SANDEN TOTTEN: Wait. Really?

KATHRYN SUNDQUIST: It's true. In one study, researchers brought together a group of kids. One half of the group ate sugar and the other half didn't. Then the researchers watched the behavior of all the kids afterwards, and they couldn't tell which kids had eaten the sugar and which ones hadn't. It wasn't like the sugar group was bouncing around and the non-sugar group wasn't.

SANDEN TOTTEN: But every time I eat sugar, I do act bonkers. Like at birthday parties, I ate a piece of cake and I can't wait to jump in a bounce house and yell at the top of my lungs. Oh, and I just ate my whole candy stash, and Penelope and I have been running around dancing and jumping and generally cavorting ever since.

KATHRYN SUNDQUIST: That makes perfect sense because most of the time when we think we have sugar rushes, we're actually just excited about something else going on around us. Like today, maybe you were just happy to hang out with Penelope and run around with her when she had her zoomies. Or when you were at that birthday party, you were actually just excited there was a bounce house and lots of presents. The sugar wasn't making you act out of control. It was all the fun and excitement of the occasion itself.

SANDEN TOTTEN: Well, maybe you're right. And actually, I'm starting to think sugar rushes aren't real because I feel like I could fall asleep at any second.

KATHRYN SUNDQUIST: Oh, I forgot to mention. Sugar crashes are very real.

SANDEN TOTTEN: Oh, boogers. Really?

KATHRYN SUNDQUIST: Sadly, yes. When you eat more sugar than usual, your body releases something called insulin, which helps to lower the amount of sugar in your blood. This keeps the amount of sugar in your blood at a normal level. But after all the sugar you eat is used up, you're left with much lower levels of sugar in your blood than before you ate the sugar in the first place. When you have low blood sugar, it can make you feel tired or even cranky.

SANDEN TOTTEN: I'm not cranky. You're cranky. I'm now going to take a nap. Come on, Penelope.



ZOE: Oh, it's so cute. I didn't realize Sanden and Penelope could fit in that doggy bed at the same time.

MOLLY BLOOM: It happens a lot.

KATHRYN SUNDQUIST: They're even snoring in unison. Adorable.

SANDEN TOTTEN: Vegetables.

ZOE: OK, I'm going to go ahead and tiptoe out of here.

SANDEN TOTTEN: Snuggle in here closer, Penelope.


ZOE: Humans have evolved to love sweet things. Because if something sweet, it means it has sugar in it.

MOLLY BLOOM: Sugar gives us energy, and also allows us to build fat to store that energy for later.

ZOE: Sugars are in a lot of foods like carrots, potatoes, rice and apples.

MOLLY BLOOM: But those foods have a lot of other things in them too, like fiber and vitamins, and they take longer for your body to break down than just plain sugar.

ZOE: Sugar rushes aren't real.

MOLLY BLOOM: You're getting energy from the sugar you eat, but that extra level of excitement comes from your circumstances.

ZOE: But sugar crashes are definitely real.

MOLLY BLOOM: That's it for this episode of Brains On.

ZOE: This episode was produced by Menaka Wilhelm, Sanden Totten, Marc Sanchez, Ruby Guthrie and Molly Bloom.

MOLLY BLOOM: We had engineering help from Johnny Vince Evans and production help from Tricia Belbita and our intern is Kathryn Sundquist. Our executive producer is Beth Pearlman and the executives in charge of APM Studios are Lilly Kim, Alex Shaffer, and Joanne Griffith. Special Thanks to Rosie DuPont, Nadine Cavanaugh, and Nick Gillis.

ZOE: Brains On is a nonprofit public radio program.

MOLLY BLOOM: You can support the show and help us keep making new episodes by heading to While you're there, you can donate, join our free fan club, or check out our merch.


Before we go, Zoe, let's go back to that mystery sound again. Here it is.


ZOE: I think that is definitely a nice scraping because I thought I heard some kitchen sounds in the back there. Maybe like a knife scraping or a knife being sharpened. Yeah, like basically what I thought before.


ZOE: So what's the answer?

MOLLY BLOOM: Oh, here's the answer.

BEN: Hi, I'm Ben I'm from Denver, North Carolina. That was the sound of me peeling carrots. I was peeling carrots for Thanksgiving dinner. I find them sweet when they're in a carrot cake. And the best time in my opinion to eat carrots is when the carrot cake just came out of the oven.

MOLLY BLOOM: So you were not so far off. It was in the kitchen.

ZOE: There is something happening with knives.

MOLLY BLOOM: Yeah, it was in the kitchen, there was a metal implement being scraped against something else, which is exactly what you said. It just happened to be being scraped against a carrot. I think that's pretty great.


ZOE: Now, it's time for the Brains Honor Roll. These are the kids like Ben who send us their mystery sounds, drawings, questions and high fives.



Brains On will be back soon with more answers to your questions.

ZOE: Thanks for listening.

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