美国国家公共电台 NPR You Don't Have To Go No-Carb: Instead, Think Slow Carb（在线收听）

STEVE INSKEEP, BYLINE: Some people who watch what they eat may be overlooking the most important things. Counting calories is a bit too simple. Cutting carbs is a bit too hard. So what can you do? NPR's Allison Aubrey has a different strategy.

ALLISON AUBREY, BYLINE: Have you ever stopped to think, what is a calorie? To find out, we're going to bring out a blowtorch.

MATT HARTINGS: If there's anything 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.

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

AUBREY: We've got two different kinds of foods here. We've got a piece of white bread, and we've got a little handful of whole-grain 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.

Now we need to measure how much heat each piece of food is giving off. That's where the calorie count comes from.

HARTINGS: You see the smoke coming up from in there?

AUBREY: 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: It turns out that the white bread we burned has about the same number of calories as the wheat kernels. But...

HARTINGS: How the calories themselves burn in our bodies is different from one food to the next.

AUBREY: And once you understand how this really works, it just may change the way you eat. For me, I realized that if I start the day with a pastry or a bagel, I'm hungry an hour later. But if I eat an egg, I'm good until 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 of Boston Children's Hospital. He's a physician who founded a weight loss clinic. Now, remember those whole grains we just burned? He says they've got a lot going for them.

LUDWIG: They take a while to digest, leading to a gentle rise of blood sugar and insulin after the meal.

AUBREY: And that's good. But the white bread, on the other hand, is more likely to lead to a spike and a crash in your blood sugar. That's because all the good stuff, like the fiber and the germ, have been processed out. All that's left is the starch.

LUDWIG: According to one way of thinking, these processed carbohydrates raise blood sugar and insulin, and that directs calories more into storage in fat cells.

AUBREY: So eating a lot of refined carbohydrates can make us hungry, maybe put us on a path to weight gain and, over the long term, may increase the risk of Type 2 diabetes. And it's not just white bread. Think of all of the snack foods we encounter every day, even here at the NPR headquarters.

OLIVER DEARDEN, BYLINE: The biggest cause of obesity in the United States is offices.

AUBREY: (Laughter).

That's Oliver Dearden. He works on All Things Considered, and he sits just a few feet away from one of the best free-food tables at NPR.

DEARDEN: Open bags of chips...

AUBREY: And some cookies left over from a meeting.

DEARDEN: People are like bees. They'll just come and just swarm around it. It's gone.

AUBREY: And it's pretty clear that none of this stuff has any whole grain left in it. It's just a bunch of refined starch and sugar. So David Ludwig's advice is this.

LUDWIG: Just get off the roller coaster.

AUBREY: In other words, you want to try to cut way back on all those foods that just don't give your body much of what we need.

INSKEEP: Allison Aubrey, I've got a question. What about just going with no carbs, as some people try?

AUBREY: Hi there, Steve. If you try to give up all carbs, you're going to set yourself up to fail. I mean, think of fruit and beans. They are loaded with carbohydrates. But when you eat a piece of fruit, you're getting a lot of fiber. You're getting a lot of micronutrients. When you eat beans, it's a great source of protein. So you don't want to give up all carbs. Instead of going no-carb, why don't you go slow-carb?

And by that I mean you want carbs that digest slowly, like the whole grains we just heard about, the fruits and beans. You know, when you eat rice, opt for the brown rice instead of the refined white rice.

INSKEEP: I guess it's not too hard to avoid white bread. I could just buy wheat bread, or whatever. But on some level, are the bad carbs - if that's the right way to phrase it - are they just going to be very hard to avoid?

AUBREY: They're just sort of empty carbs, and they are hard to avoid. But you can just sort of change the way you shop. I mean, here's what I had for breakfast this morning. This is a three-grain bread, just sort of, like, traditional pumpernickel rye.

INSKEEP: OK. Thank you.

AUBREY: Have a little bite. Now, if you look at that, it's got the grain. It's still intact. Now, that's a sign that it's a whole grain.

INSKEEP: OK.

AUBREY: Here. I'm going to hand you this little wheat kernel here.

INSKEEP: OK.

AUBREY: Now, if you were to pop that open, what you would find is a little germ. And I want you to think about that germ as a little packet of nutrients. It's got magnesium. It's got zinc. It's got potassium. All of that stuff is good for you. It's also got a ton of fiber.

But think about it. All that good stuff is stripped out of all of these refined snacks and breads we eat. Do you want to eat that way?

INSKEEP: No.

AUBREY: (Laughter). OK.

INSKEEP: But I'm going to eat this bread. It's pretty good. Thank you very much. Am I eating your breakfast?

AUBREY: You are just eating my leftovers.

INSKEEP: OK. Fine. Fine. Do you have any advice for when you don't bring me breakfast, like you just did?

AUBREY: (Laughter). You know what? I'm going let you off the hook here. I'm going to say it's fine to eat those croissants or that baguette out there. Because you know what? It's completely unrealistic to think that these things are going to go away. Right? Like, I love a good croissant. I mean, I'm sure you do, too. I'm sure all of you out there do.

INSKEEP: They can go away when I eat them.

AUBREY: (Laughter) Right. But here's one thing to remember. If you want to eat those kind of things, eat them at the end of a meal. And here's why. The timing of when you eat these refined carbs really does seem to matter. In fact, there was this cool little study done a few years back. It found that compared to eating bread at the beginning of the meal, if you eat bread at the end of the meal, it actually lowered the peak blood sugar of people in the study by about 30 percent, which is big.

Now, this trick might not have the same effect on everyone, but it does suggest that the timing really matters. So think about bread as dessert.

INSKEEP: And lower blood sugar means I don't get kind of a sugar high, I don't crash later, I don't get hungry later?

AUBREY: Exactly. Short-term effect of that would be maybe you don't get hangry. Long-term effect of that is you cut the risk of Type 2 diabetes.

INSKEEP: OK. We want to mention that these tips are from Allison's latest episode of Life Kit. What is that?

AUBREY: OK. Life Kit is our new family of audio guides to help you navigate your life, Steve. We've got one new one coming out today. It's on making smarter decisions when it comes to eating well.

INSKEEP: OK. So eat the bread at the end of the meal...

AUBREY: You got it.

INSKEEP: ...Listen to the podcast before the meal.

AUBREY: (Laughter). You're good.

INSKEEP: Allison, thanks so much.

AUBREY: Thanks, Steve.

INSKEEP: That's NPR's Allison Aubrey. And you can find Life Kit guides wherever you get podcasts or at npr.org/lifekit.