Mind Over Milkshake: How Your Thoughts Fool Your Stomach
It was late, almost 9 at night, when Justin Holden pulled the icy pizza box from the refrigerator at the Brookville Supermarket in Washington, D.C.
He stood in front of the open door, scanning the nutrition facts label.
A close relative had recently had a heart attack, and in the back of his mind there was this idea stalking him: If he put too much salt in his body, it would eventually kill him.
For this reason the information in the label wasn't exactly soothing: 1,110 milligrams of sodium seemed like a lot.
But there was even worse-sounding stuff at the bottom of the label.
Words like "diglyceride," with a string of letters that clearly had no business sitting next to each other. It suggested that something deeply unnatural was sitting inside the box.
"Obviously it's not good for me," the 20ish Holden said. "But, hopefully, I can let it slide in."
He tucked the pizza under his arm, and headed one aisle over for a sports drink.
A Label Is More Than A Label
Who among us has not had a moment like this? That intimate tete-a-tete with the nutrition label, searching out salt, sugar, fat, trying to discern: How will you affect me? Are you good? Or are you bad?
Here's the thing you probably haven't stopped to consider: how the label itself is affecting you.
"Labels are not just labels; they evoke a set of beliefs," says Alia Crum, a clinical psychologist who does research at the Columbia Business School in New York.
A couple of years ago, Crum found herself considering what seems like a pretty strange question. She wanted to know whether the information conveyed by a nutritional label could physically change what happens to you — "whether these labels get under the skin literally," she says, "and actually affect the body's physiological processing of the nutrients that are consumed."
As a student, Crum had spent years studying the placebo effect — how a sugar pill can physically alter a body if the person taking the pill believes it will. She figured food labels might work the same way. So she came up with an experiment.
Crum created a huge batch of French vanilla milkshake, then divided it into two batches that were labeled in two very different ways.
Half the stuff was put into bottles labeled as a low-calorie drink called Sensishake — advertised as having zero percent fat, zero added sugar and only 140 calories.
The other half was put into bottles that were labeled as containing an incredibly rich treat called Indulgence. According to the label, Indulgence had all kinds of things that wouldn't benefit your upper thighs — including enough sugar and fat to account for 620 calories. In truth, the shakes had 300 calories each.
Both before and after the people in the study drank their shakes, nurses measured their levels of a hormone called ghrelin.
Ghrelin is a hormone secreted in the gut. People in the medical profession call it the hunger hormone. When ghrelin levels in the stomach rise, that signals the brain that it's time to seek out food.
"It also slows metabolism," Crum says, "just in case you might not find that food."
But after your ghrelin rises, and you have a big meal (say a cheeseburger and a side of fries), then your ghrelin levels drop. That signals the mind, Crum says, that "you've had enough here, and I'm going to start revving up the metabolism so we can burn the calories we've just ingested."
On the other hand, if you only have a small salad, your ghrelin levels don't drop that much, and metabolism doesn't get triggered in the same way.
For a long time scientists thought ghrelin levels fluctuated in response to nutrients that the ghrelin met in the stomach. So put in a big meal, ghrelin responds one way; put in a small snack and it responds another way.
But that's not what Crum found in her milkshake study.
If you believed you were drinking the indulgent shake, she says, your body responded as if you had consumed much more.
"The ghrelin levels dropped about three times more when people were consuming the indulgent shake (or thought they were consuming the indulgent shake)," she says, compared to the people who drank the sensible shake (or thought that's what they were drinking).
Does that mean the facts don't matter, that it's what we think of the facts that matters?
"I don't think I would go that far yet," Crum says. More tests need to be done, she says, to figure out exactly how much influence comes from food and mindset.
But she does think the usual metabolic model — calories in and calories out — might need some rethinking, because it doesn't account in any way for our beliefs about our food.
"Our beliefs matter in virtually every domain, in everything we do," Crum says. "How much is a mystery, but I don't think we've given enough credit to the role of our beliefs in determining our physiology, our reality. We have this very simple metabolic science: calories in, calories out."
People don't want to think that our beliefs have influence, too, she says. "But they do!"
Meanwhile, Back At The Brookville Supermarket
As for Holden, after he retrieved his sports drink, he picked up a salad, then carried his items to the cashier and put them down on the conveyor belt.
The liquid of his sports drink almost glowed under the lights of the store as the cashier rang him up.
Holden told the man he didn't want a bag. He carried his pizza out into the night.
Within an hour, the pizza and drink would be in his stomach, mingling there with a set of beliefs that he got from the back of a box.
KELLY MCEVERS, HOST:
It's MORNING EDITION from NPR News. Good morning, I'm Kelly McEvers.
DAVID GREENE, HOST:
And I'm David Greene.
Today, in Your Health we're looking at food labels. At the grocery store you might glance over the labels on items on the shelves, checking the amount of sugar, fat, cholesterol. Well, this story from NPR's Alix Spiegel that make you think differently about these labels and their impact.
Alix begins in a grocery store here in Washington, D.C.
ALIX SPIEGEL, BYLINE: It was late, and the frozen food section of the Brookville grocery was almost deserted. There was only one person there, a man in dark clothes standing in front of a wall of icy pizza boxes. His name was Justin Holden.
It's like almost nine o'clock at night and you' re coming for dinner?
JUSTIN HOLDEN: It was a late night at work. I do sales, so.
SPIEGEL: Oh, I see. So you're getting a frozen pizza?
HOLDEN: It's cheaper than ordering delivery.
SPIEGEL: Justin pulled out one of the pizza boxes and scanned it, looking for nutrition facts; 750 calories...
HOLDEN: Twelve grams of fat, five grams of it is saturated fat.
SPIEGEL: Justin had a close relative that had recently had a heart attack. In fact, Justin says that both sides of the family struggle with heart disease and that's why he always read these labels. In the back of his mind, there was this idea stalking him. If he put too much salt into his body it would eventually kill him.
HOLDEN: One thousand one hundred forty milligrams of sodium.
SPIEGEL: That didn't exactly seem healthy. But at the bottom of the nutritional facts under ingredients was even scarier stuff, words like diglyceride with a string of letters that clearly had no business sitting next to each other. And so conveyed the message that there was something deeply unnatural about the food inside the box.
Do you think this is good for you or not good for you?
HOLDEN: No. Obviously it's not good for me. But I eat out one night a week, so hopefully, you know, I can let it slide in. But I know. I know it's not good for me.
SPIEGEL: Who among us has not had this moment, that kind of intimate tete-a-tete with the nutritional label searching salt, sugar, fat? Trying to discern how will you affect me, are you good or are you bad? But here's the thing you probably haven't considered. How does the label itself affect you.
ALIA CRUM: The labels are not just labels. They evoke a set of beliefs.
SPIEGEL: This is a psychologist named Alia Crum who works at Columbia University. And a couple of years ago, she found herself seriously considering what on it's face seems like a pretty strange question. She wanted to know whether the information in a nutritional label could somehow change what happens to you biologically.
CRUM: Whether these labels get under the skin literally, so they don't just effect perception and taste and behavior but actually effect the body's physiological processing of the nutrients that are consumed.
SPIEGEL: See, Crum had spent years studying the placebo effect, how a sugar pill can physically change a body if the person taking believes that the sugar pill will change their body. And she figured that food labels might work the same way. And so, to test her idea, Crum created a huge batch of milkshakes.
CRUM: It was sort of a French vanilla flavor.
SPIEGEL: Was it delicious?
CRUM: It was delicious, in my opinion.
SPIEGEL: Did you taste it, you know, just for science?
CRUM: I did taste it for science.
SPIEGEL: Then she took that single batch of milkshakes and gave them to groups of people labeled in two very different ways. Half of the single batch of milkshakes was put in a bottle that was branded as a low calorie drink.
CRUM: Called Sensi-Shake. And do you want me to read the label?
SPIEGEL: Yeah, read the...
CRUM: Says zero percent fat, zero added sugar, and only 140 calories - guilt free satisfaction.
SPIEGEL: The other half of the single batch was put in a bottle that was branded as an incredibly rich and delicious treat.
CRUM: Indulgence is the name of it. And the subscript is: decadence you deserve.
SPIEGEL: With an extremely high calorie count.
CRUM: Six hundred and twenty calories.
SPIEGEL: OK, so it's the difference between how many...
CRUM: Six hundred and twenty calories in the Indulgent shake and 104 calories in the Sensi-Shake.
SPIEGEL: And then both before and after the people drank the shake - which, by the way, was actually a 300 calorie shake - nurses monitored their levels of this hormone called ghrelin.
CRUM: Ghrelin is a gut peptide. It's secreted in the gut. People in medical field call it the hunger hormone.
SPIEGEL: Basically, when you haven not eaten anything, ghrelin levels in the stomach rise which signals to the brain that it's time now to seek out food.
CRUM: It also, interestingly, slows metabolism. So rises in ghrelin signal hunger and slows metabolism, just in case you might not find that food.
SPIEGEL: But after that rise, say you have a big meal.
CRUM: Hamburger with cheese and French fries and a milk shake, gherlin levels are going to drop a lot. And what that does, is it signals to the mind, you've had enough here, you know, and I'm going to start revving up the metabolism so we can burn these calories were just ingested.
SPIEGEL: On the other hand, say you only have a small salad, your ghrelin levels wouldn't drop that much.
CRUM: They maybe would just drop a teeny bit. And what that would signal is, you know, a combination of, mm, I'm not feeling physiologically satiated, maybe you need to eat more food.
SPIEGEL: And the metabolism doesn't get revved up in the same way.
Now for a long time, the idea has been that these fluctuations in ghrelin levels were responses to the actual nutrients that the ghrelin met in the stomach. So put in a big meal, ghrelin responds one way; put in a small snack, ghrelin responds another. The thing that was believed to be important was the actual content of the food - not your beliefs about that food.
CRUM: The label wouldn't matter.
SPIEGEL: But in her milkshake study, that is not what Crum found. If you believed that you were drinking the Indulgent shake, your body responded as if you had just consumed three times more food.
CRUM: The ghrelin levels dropped about three times more when they were consuming the Indulgent shake - or thought they were consuming the indulgent shake - than when they were consuming the sensible shake or thought they were consuming the sensible shake.
SPIEGEL: Is that a big difference?
CRUM: That's a big difference. Yeah. It's both statistically significant also, you know, practically meaningful, considering that it was three times the drop.
SPIEGEL: Which, at least for me, raises a pretty profound question. So does that mean that the facts don't really matter, it's what we think of the facts that matter?
CRUM: I don't think I would go that far yet. There's a lot more tests that we need to do to figure out, you know, how much do the nutrients matter and how much does our mindset matter?
SPIEGEL: But Crum did say this...
CRUM: Our beliefs matter virtually in every domain, in everything we do. How much is a mystery. And I think that we haven't given enough credit to the role of our beliefs in determining our physiology, our reality. You know, we have this very simple metabolic science; calories in, calories out. People don't want to account for the fact that our beliefs matter too. But they do, and we're finding that more and more the more that we research and explore these topics.
SPIEGEL: After he finished in the frozen pizza section, Justin Holden wandered a couple isles over and got himself a bright blue sports drink to go with it. The liquid almost glowed under the lights of the store as he put his stuff on the conveyor belt in front of the cashier.
(SOUNDBITE OF BEEP)
HOLDEN: Thank you. No. I'll carry it. Thank you.
SPIEGEL: Holden didn't want a bag. When he was done he just picked up his dinner and tucked it under his arm and went out into the night. Within an hour, the pizza would be in his stomach, mingling there with a set of beliefs that he got from the back of a box.
Alix Spiegel, NPR News, Washington.
(SOUNDBITE OF SONG, "MILKSHAKE")
KELIS: My milkshake brings all the boys to the yard. And there like, it's better than yours.
GREENE: It's MORNING EDITION from NPR News. Transcript provided by NPR, Copyright NPR.