The Truth About Carbs And Calories Carbs get a bad rap. Here's the science behind why eating too much starch isn't good for you — and smart tips to integrate more slow carbs into your diet.

The Truth About Carbs And Calories

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We hear a lot about calories. They're printed on labels and menus, and we're told if you want to lose weight, you got to eat fewer of them. But have you ever stopped to think, what is a calorie? Well, the best way to find out involves getting out a blowtorch.

MATT HARTINGS: If there's anything that we chemists know how to do, it's burn things.

AUBREY: That's Matt Hartings. He's a chemistry professor, and we're in his lab at American University. He's got the technical definition of a calorie.

HARTINGS: The calorie is the amount of heat required to raise the temperature of 1 gram of water 1 degree Celsius.

AUBREY: But what does that really look like?

HARTINGS: So what we're going to do is we are going to burn our food. You ready?



AUBREY: We've got two different foods here, a piece of white bread and a handful of little wheat kernels.

HARTINGS: So I've got my propane torch here that we're going to use to start this bread the way it needs to be going.

AUBREY: All right. Let's do it.

We need to measure how much heat each piece of food gives off. That's where the calorie count comes from.

HARTINGS: Now, you see the smoke coming up from in there?

AUBREY: Oh, yeah. Look at that flame. That's a lot of smoke.

HARTINGS: It is a lot of smoke. These things are reacting with oxygen or burning. And we're measuring the amount of energy that comes off when they burn, right? It's the same reaction that goes on in our bodies.

AUBREY: Turns out that white bread we just burned has about the same number of calories as the whole-grain wheat kernels. But just because they have the same number of calories...

HARTINGS: How the calories themselves burn, if we want to think about it that way - how they burn in our bodies is different from one food to the next.

AUBREY: And once you know how this works, it just might change the way you eat.


AUBREY: This is your NPR LIFE KIT for healthy eating. In this episode, the lowdown on calories and carbs. We explain how carbs work in your body and give you some strategies to eat them smartly. And I promise, the answer is not no-carb. That's coming up in a minute.


AUBREY: I'm Allison Aubrey. I cover health and wellness here at NPR, and in this episode, we're talking about the science behind carbohydrates. And later in the episode, we'll talk to a chef about how to eat them.

And, you know, I should say right up front we are not here to vilify carbs. They're fuel for our bodies. And me, personally, I love bread. Like, when I'm on my deathbed, skip the morphine. Just give me a conveyor belt of chocolate croissants. (Laughter) I know that sounds morbid, but I mean it.

So I've had to learn to eat carbs pretty differently. I know that if I start the day with a pastry or muffin, I'm hungry - even starving - an hour later. But if I have an egg in the morning, it holds me till lunch. It's got some fat and protein.

DAVID LUDWIG: We've known for decades, if not a century, that different foods affect the body differently apart from their calorie content.

AUBREY: That's David Ludwig. He's a professor of nutrition at the Harvard School of Public Health, and he's the founder of a weight loss center at Boston Children's Hospital. He has thought a lot about the role of carbs in our diets. And he has our first takeaway.

LUDWIG: A calorie isn't just a calorie. When you eat one food, your hormones, metabolism and even the expression of your genes changes in very different ways from other foods.

AUBREY: So let's try to unpack that a little bit. That white bread and those wheat berries we set on fire, they have about the same number of calories. And they're both carbohydrates, but the whole grain has so much more going for it.

LUDWIG: When you eat a whole kernel, minimally processed grain - so things like wheat berries, whole oats, barley and rye - they take a while to digest. Blood sugar rises relatively more gently. You produce less insulin calorie for calorie.

AUBREY: And that's a good thing. But when you eat the white bread, there's a very different reaction. All the good stuff is processed out of the bread, leaving just a bunch of starch.

LUDWIG: And it slams into the bloodstream, raising blood sugar and insulin.

AUBREY: Which can lead to other bad effects.

LUDWIG: Potentially stimulating hunger, maybe even slowing down metabolism.

AUBREY: And here's your second takeaway. You've heard to cut back on sugar. Well, starch is pretty close to sugar. In your body, it's one step away. I don't want to put too fine a point on this, but would it be exaggerating if I said, hey, if you're going to eat that piece of white bread, you might as well be eating Skittles?

LUDWIG: Right. You know, you can have a bowl of cornflakes with no added sugar or you can have a bowl of sugar with no added cornflakes. They'll taste different, but below the neck, they're going to fundamentally do the same thing.

AUBREY: I mean, that's kind of probably a shock to people.

LUDWIG: According to one way of thinking, these processed carbohydrates that have flooded our diet raise blood sugar and insulin. And that directs calories more into storage and fat cells. So there are fewer calories available for the rest of the body, for the organs, the muscles and the brain. That's why we get hungry.

AUBREY: So here's the deal. If you eat carbs smarter, you can break the cycle of hunger, which brings us to whole grains.


AUBREY: You've probably heard that whole grains are better for you. But do you know why? I mean, what makes them whole? That's what confuses people. Well, do you know what a whole grain - how would you define whole grain? What is a whole grain?

AYURA RILEY: A whole grain...

AUBREY: I talked to a bunch of people, like Ayura Riley (ph) about this. Most of them have a pretty vague understanding of what whole grain actually means.

RILEY: I guess I just look at the package - as long as it's whole grain and it looks brownish and it doesn't taste as good.

AUBREY: So let's do a quick primer on what a whole grain actually is. So when you're in the grocery store and you see something that says 100 percent whole grain, here's what I want you to think about.

I want you to imagine a little kernel.

LUDWIG: Something that looks like it came from a plant.

AUBREY: I actually have some of these in my hand right now, little wheat berries. They look like seeds. And here's the key thing to remember. They've got three parts. In the center here is a little germ. Think of it as a tiny, little packet of nutrients.

LUDWIG: The germ is the part out of which the new plant grows. And so it's going to have the most concentrated source of nutrients. And it has protein and a few essential fatty acids.

AUBREY: And that's really healthy for you. Then there's the bran.

LUDWIG: The bran is fiber, and we know that this kind of fiber can be good for digestive health.

AUBREY: That's why it can be good to eat the whole grain. Get it? Whole grain. You're getting a whole packet of nutrients at once.

LUDWIG: When that grain is eaten in an intact form, it's got all of the nutrients. And it tends to digest more slowly, leading to a gentle rise of blood sugar and insulin after the meal.

AUBREY: This can help us feel full longer and help keep blood sugar stable so you don't get hangry (ph). But here's the problem. Most of us are completely missing out. I mean, if you look around, people are not snacking on wheat berries. I mean, just check out the free food tables here at NPR. I'm going to take you on a little tour.

ALI: The biggest cause of obesity in the United States is offices.

AUBREY: That's Ali (ph). He works at All Things Considered, and he sits just a few feet from one of the best free-food tables in the building. It's full of stuff.

ALI: Open bags of chips.

AUBREY: Or leftover cookies from meetings.

ALI: People are like bees. They'll just come just swarm round it. It's gone.

AUBREY: And there are tables like this all over the building. I'm not kidding.

UNIDENTIFIED NPR EMPLOYEE #1: Doughnuts, cookies, chocolate...







UNIDENTIFIED NPR EMPLOYEE #8: When the pizza is, like, three or four hours old, and it's definitely cold.

UNIDENTIFIED NPR EMPLOYEE #9: There's, like, half a pie there, and nobody knows where it came from.

AUBREY: And what do you hear about all those snacks? You think there's any whole grains there? Nope. All that's left in that pizza or pie crust is the third part of the grain. It's called endosperm.

LUDWIG: The endosperm, the starchy part, is really just glucose in a long chain, which has very little additional nutritional value but can send blood sugar skyrocketing in highly processed grain products.

AUBREY: So your blood sugar goes up, and then it crashes.

LUDWIG: The simple solution is just get off the roller coaster.


AUBREY: I know we've been trashing carbs, but let's talk about a way to enjoy bread. I mean, I love it. And David says there are much better options than white bread.

LUDWIG: Even today, you can find traditionally produced breads. They're minimally processed, such as in traditional pumpernickels. Sourdough processing is a very nice way to make bread because it tends to digest some of that rapidly available starch. And so the remaining part of the bread is the more nutritious part.

AUBREY: In other words, there's some evidence to show that the sourdough can help slow down the release of sugar into your bloodstream. And here's another trick, and it's takeaway No. 3 - timing counts. Don't eat bread or pastries at the beginning of a meal. David Ludwig has done some research on this.

You and I talked about a study done a few years back where they gave people the rolls at the end of the meal compared to the beginning of the meal. And they found, on average, the people who ate those rolls at the end, they had about a 30 percent lower peak in their blood sugar.

I thought that was really fascinating, the timing of when you eat these starches can make a difference.

LUDWIG: That's the place to start - not only reducing them, but keeping them as small servings, ideally toward the end of the meal, like a dessert. By that point, you've eaten your protein, healthy fats, fiber, plenty of vegetables. Your gastrointestinal tract is filled up with these good foods. And that processed carbohydrate isn't going to hit an empty stomach and slam into your bloodstream.

AUBREY: Now, in this study, they just looked at bread, but it's also a good tip for pastries, muffins or really any refined carbs.

So what's a better way of eating? If you don't want to eat much refined starch for the reasons you just explained, what do you want to add in? You're telling us what to take out. What should we add in?

LUDWIG: So I don't - I don't argue that everybody has to be on a low-carbohydrate diet. I think what we want to do is focus on reducing these highly processed carbohydrates and replacing them with whole fruits, beans, nuts, a variety of healthy fats, making sure to get enough protein. That's going to give your body an extra chance.

AUBREY: So that's your takeaway No. 4 - focus more on whole foods, healthy fats and protein.


AUBREY: Now, how do we put all of this into practice in the kitchen?

DAWN LUDWIG: That's really my specialty. I take David's science, and I translate it into practical application.

AUBREY: David Ludwig has teamed up with Dawn Ludwig. She's a professional chef, and they happen to be married.

DAWN LUDWIG: I don't want anyone to feel deprived. I don't want anyone to feel like they have to be on some extreme diet that they give up anything. I want to meet people where they are.

AUBREY: Let's break this down into a typical day, starting with breakfast. A lot of us grab cereal or a bagel, but we're hearing those aren't the best options. So Dawn's got a great alternative.

DAWN LUDWIG: I do a recipe for overnight oats, where you take either whole oat groats or steel-cut oats, which are minimally processed, you bring it to a boil in a heavy pot the night before. And you can use milk or water or any non-dairy milks - four parts of water to one part of oats. You bring it to a boil. You boil it for a minute. You put the lid on, and then you turn it off. You leave it overnight. You wake up. You heat it, and you've got whole oat groats instead of instant oats. It's quick. It's easy. It's delicious.

AUBREY: Why are these better than that little package you get of the little instant oats?

DAWN LUDWIG: It's going to take longer to digest. Your body is going to slowly digest it. So it's not going to raise insulin.

AUBREY: She calls foods like these steel-cut oats slow carbs.

DAWN LUDWIG: And I'll often look at, how long does it take to cook? If it's going to cook in three minutes, you know it's been broken down into sugars already. And it's going to absorb really quickly and raise your insulin. If it's going to take an hour to cook, then it's slower-acting.

AUBREY: So here's one rule of thumb. The longer it takes to cook a grain, the longer it's likely to keep you full. So now let's turn to lunch. And now that we understand that, in your body, starches basically almost like sugar, you want to avoid that post-lunch crash. So Dawn says remember this.

DAWN LUDWIG: Well, I think the word that comes to mind is disassembled.

AUBREY: Disassembled.

DAWN LUDWIG: Yeah. So maybe it's a sandwich, but it's a disassembled sandwich. You leave off the bread and maybe put some lettuce with it. You'll be surprised.

AUBREY: How about half the bread? (Laughter).

DAWN LUDWIG: Half the bread.


DAWN LUDWIG: Absolutely. Like, we're...

AUBREY: (Laughter) Now you're talking.

DAWN LUDWIG: ...Going to meet you where you are. Do half the bread. Do an open-faced sandwich. Or...

AUBREY: Go for sourdough.


AUBREY: Go for pumpernickel.

DAWN LUDWIG: Yes, or a burrito. Just...


DAWN LUDWIG: ...Do the burrito bowl instead of the tortilla with it.

AUBREY: You know, Dawn is a big fan of leftovers. Think about it this way. You want to cook once and eat twice. But instead of just reheating that stir fry from last night, think about adding a new component, say, some veggies or an avocado. This way, you might be more excited about eating it.

DAWN LUDWIG: So when you open your lunch and you look at it, you're not longingly looking across the sandwich shop because your lunch looks...

AUBREY: (Laughter).

DAWN LUDWIG: ...So - like a big glob of something.


AUBREY: And when you think about a healthy dinner, fill half your plates with fruits and vegetables. As for the other half of the plate, Dawn says think of it this way.

DAWN LUDWIG: Concentrate first on the fat and the moderate amount of protein in your diet and in your food. And then have the whole grain be the side dish or the afterthought. First, look at what's your fat, what's your 4 to 6 ounces of protein? And then think about what is going to be the slow carb.

AUBREY: So when you talk about fat, are you talking about, you know, you're cooking with olive oils or plant-based oils. What are you usually talking about when you mean good fat?

DAWN LUDWIG: So good fat - good olive oils, exactly, sometimes avocados, nuts. I do a lot of really simple five-minute sauces that I have in my fridge that I can pull out and put a, you know, Greek dressing or a Moroccan sauce or a coconut curry or a quick balsamic cashew sauce on something and have it round out the meal with that kind of a fat.

AUBREY: Those sound wonderful. They sound wonderful, but they don't sound quick. Can you give us, like, an example of something that is easy, something I could pull off? I've got three kids and a full-time job. (Laughter).

DAWN LUDWIG: So I came up with this idea to take a Ball canning jar - you know, just a mason jar.


DAWN LUDWIG: And I don't like cleanup either. So if I can do less cleanup, that's going to be better. So I put all these ingredients - for example, my Moroccan sauce or my Thai peanut sauce that I do - I put all the ingredients in a a canning jar. And I take an immersion blender, and I stick it in. And I blend it up, and I rinse the end of it. And I put a lid on it, and I stick it in my fridge.

AUBREY: Ah, so one of those little blender sticks that you could just stick right into the canning jar.

DAWN LUDWIG: It's my favorite tool in the kitchen.

AUBREY: Sound good? Well, we've got some of those recipes at And just to show you how quick it is, here's how Dawn makes her Thai peanut sauce.

DAWN LUDWIG: I would take a whole orange or a few tangerines, put them in there with some peanut butter, some rice vinegar or whatever vinegar you've got, a little bit of chili pepper to give it a little bite and a little water. But these whole oranges, as I blend them, the fiber's...

AUBREY: They just give a little bit of sweetness.

DAWN LUDWIG: ...Still going to be in there.


DAWN LUDWIG: It does. It does, and it's - it's not juice. It's the whole thing. And it is absolutely - this is one of the favorite recipes that - that I've made. People love it.

AUBREY: Got it. And then when you haven't used all of it, you can just put the canning jar back on top and stick it back in the fridge.

DAWN LUDWIG: That's right. And when you take it out, you might say, OK, I'm home from work. It's late. My kids are hungry. So you grab some protein and some veggies. Maybe you've pre-cut them or bought them pre-cut, or you just cut a few real quick. Put it in a pan. Pour a little Thai peanut sauce on it. Saute it until the protein is done, and 15 minutes, you've got dinner on the table. And it's restaurant quality.


AUBREY: Can I just come and live in your house...

DAWN LUDWIG: (Laughter).

AUBREY: ...Because I think I'd be really well-fed. (Laughter).

DAWN LUDWIG: We eat well around our house. We eat well.

AUBREY: It sounds like it.

Now a quick review of what we've learned. Takeaway No. 1 - not all calories act the same in the body. Think back to those wheat berries and that white bread we torched in the lab.

LUDWIG: Oats and white bread might have the same number of calories in a typical serving but dramatically different effects in the body.

AUBREY: Takeaway No. 2 - refined carbohydrates quickly turn to sugar in your body.

LUDWIG: Starch is nothing more than glucose sugar in a long chain, which has very little additional nutritional value, but can send blood sugar skyrocketing in highly processed grain products.

AUBREY: As for your third takeaway - if you love bread and muffins, save them for the end of your meal. Treat them like dessert.

LUDWIG: You know there's that expression, life is short, eat dessert first. Not in this case.

AUBREY: (Laughter) Bad idea.

LUDWIG: Dessert is designed to come after the meal when your stomach has already got protein, healthy fats and fiber slowing down digestion.

AUBREY: And for your final takeaway, as you try to scale back on starch, replace them with these foods.

LUDWIG: Whole fruits, beans, nuts, a variety of healthy fats, making sure to get enough protein.

DAWN LUDWIG: People on a regular basis get confused by this. They go too low-carb, and they start getting, you know, brain fog. And their body isn't responding well. And we have to remind them to put in slow carbs. Don't be afraid of slow carbs.

AUBREY: If you like what you hear, make sure to check out our other LIFE KIT guides at There, you will find a guide about how to find money you didn't know you had. And while you're there, subscribe to our newsletter so you don't miss anything. We've got more guides coming out every month on all sorts of topics.

And here, as always, is a completely random tip, this time from NPR producer Tom Dreisbach.

TOM DREISBACH: If you ever either buy a new car or rent a car or borrow a friend's car and you're wondering where the gas tank actually is on the car - which side - there's a little arrow, if you look, where the gas gauge is. And there's an arrow that goes either left or right. And it tells you which side the gas tank is. So you never actually have to get out of the car at the gas station and try and figure it out on your own.

AUBREY: I love it, Tom. If you've got a tip or want to suggest a topic for our next guide, email us at NPR LIFE KIT is produced by Sylvie Douglis, Alissa Escarce and Chloee Weiner. Meghan Keane is the managing producer. This episode was edited by Maria Godoy, music by Nick DePrey and Bryan Gerhart (ph). Our project manager is Mathilde Piard, Neal Carruth is our general manager of podcasts. And the senior vice president of programming is on Anya Grundmann. I'm Allison Aubrey. Thanks for listening.

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