MR. KOJO NNAMDIWe hear it all the time. A shocking number of Americans are obese and a lot of the reason is food. People are consuming far more calories than they're burning off and the imbalance shows up on their waistline. Given the apparent lack of personal willpower, lawmakers are getting involved. New York City's mayor wants to ban sales of sodas larger than 16 ounces and Congress has already told chain restaurants they'll have to start listing calorie counts on their menus. But should we really legislate measures to cut down on calories?

MR. KOJO NNAMDIResearchers and food economics and public health are studying whether policing calories and serving sizes actually changes consumer behavior. It's Food Wednesday and we're talking with Ben Caballero. He is a professor of pediatrics and nutrition at the Schools of Medicine and Public Health at Johns Hopkins University. He describes himself as a physician with a doctorate in nutrition. Ben Caballero, thank you for joining us.

MR. BENJAMIN CABALLEROThank you for having me here.

NNAMDIAnd joining us from studios in Ithaca, N.Y. is David Just. He's a professor of economics and director of the Center on Behavioral Economics and Child Nutrition Programs at Cornell University. David Just, thank you for joining us.

MR. DAVID JUSTThank you. Good afternoon.

NNAMDIThe number to call to join the conversation is 800-433-8850. How would you feel if restaurants and movie theaters could not sell sodas larger than 16 ounces? 800-433-8850. Send us a Tweet at kojoshow or email to kojo@wamu.org. David Just, in New York City, Michael Bloomberg, the mayor, is proposing to limit sweetened drinks to no more than 16 ounces at restaurants, movie theaters and food carts. He cites the nation's obesity epidemic and your research is making his case. But you've said you don't think the plan will work. Why not?

JUSTWell, there are a few reasons. First, you know, and foremost, it's an issue where the people who are really going to be affected by this are the people who are most likely to sort of try and find a way around it, right. Over and over again in our research, we find when we put restrictions on what people can do, we put these sort of barriers on what they can eat, that they try and push back on it. They rebel against this sort of limit called reactance in literature. And so I think that's one of the main reasons this is problematic.

JUSTBut even more so, I don't think anybody expects that this little change is going to have a big impact on obesity. And if it doesn't have an impact on obesity and it makes a large set of people really annoyed, it has a real big potential to backfire to have political will there to keep anything like this from ever happening again, right. So for decades after, people might be citing the policy in New York City and saying, let's not become the next New York City. Let's not try this or that health policy because they backfire, right.

NNAMDIBut your research shows that when people are given large sizes of food like popcorn or french-fries, they overeat. How is that different from giving them a large soda?

NNAMDIWell, one of the key parts of our research is that it shows that people who are given this in a way where they don't recognize that the amount is really being manipulated end up drinking more, eating more. And it has a big impact, but there's a very big difference between, you know, you walk into a theater or something like that and I hand you a drink or you walking into a theater and you requesting a drink and me saying, no, that type of drink isn't available, right. I mean, it almost has to be something that's at the level of the individual not really being aware in order for it to work. And as soon as you have this policy in place, it creates a super awareness of that amount of soda that they're limited to. And they're going to fight back.

NNAMDIBen Caballero, what do you think? What do you think about the plan to limit the size of sugar-sweetened sodas? Will it help people cut down on their calorie consumption?

CABALLEROWell, I think the mayor is only undoing what we did over the past 30 or 40 years. So he's not inventing nothing new, but trying to undo the tremendous increase in portion size that the food industry had brought us over the past several decades. It's true that singling out one single product perhaps may not have the impact that we need on obesity. But certainly the issue of portion size of processed food is a tremendous problem. And we have to start somewhere at some point and generate this idea that you can't just gulp 100 percent of whatever you receive.

CABALLERORemember those old days where you had the 8 ounce bottle of soft drinks and people consumed one bottle. And then they went to 12 and then 16 and then 24. People appreciate the value so I think the food industry also needs to be part of the equation and understand that simply pushing more food on the consumer in the long run is going to create tremendous problems for the health of the country.

NNAMDI800-433-8850, do you think laws -- that lawmakers should be trying to help Americans slim down? 800-433--8850. David Just, talk about the psychology of being told you cannot have something that you want, which is what the soda size limit would do for some people?

JUSTRight. So, you know, I mentioned this idea of reactance or this rebellion against any sort of threat to freedom. You know, we see this, like I said, over and over. A very good anecdote, there's a school system near here that in order to try and limit calorie intake -- this'll sound a little bit outrageous -- they limited students to taking just one packet of ketchup with their lunch, right.

NNAMDIYes.

JUSTSo they had to try to use this one single packet of ketchup for all of their chicken nuggets and whatever else, yeah.

NNAMDIAll your fries and everything.

JUSTAnd so, you know, as you would -- the students didn't particularly like this idea. They felt it was egregious. And because of that, they actually organized this protest. And the protest was pretty simple. It was nothing that was going to harm anybody. At graduation, as they're walking across the stage, each senior hands the principal a packet of ketchup, right. And now this doesn't hurt anybody, but it does send this message.

JUSTBut what it really tells you is if they cared that much, right, if they really cared that much about that packet of ketchup, when they get to McDonald's or they get to some other place where the ketchup is not limited, they're not -- they didn't develop a habit of, you know, only taking one. They're now grabbing handfuls and saying, free at last, right. They're not going to be influenced by this. That's what that reactance does is it puts up a barrier to actually changing habits. And so...

NNAMDIWe're talking about -- go ahead.

JUSTSo I -- a colleague that was just on before talking about, you know, government working with industry, I think that's actually a very good way to go. Because industry can find ways to get consumers to want to do things, right. They can use their techniques to try and help consumers want to consume less.

NNAMDIDavid Just. He's a professor of economics and director of the Center on Behavioral Economics and Child Nutrition Programs at Cornell University. He joins us from studios in Ithaca, N.Y. for our conversation on legislating how much we eat. In our Washington studio is Ben Caballero. He is a professor of pediatrics and nutrition at the Schools of Medicine and Public Health at Johns Hopkins University. I'd like to go to the phones. Here is Amy in Tacoma Park, Md. Amy, you're on the air. Go ahead, please.

AMYHello. I've got a question about my niece. She is kind of a little bit overweight and we're starting to get worried. So almost along with the (word?) that you gave, my sister doesn't want to always say no, no, no. But we're kind of looking for strategies to get my niece -- she's four -- to manage serving sizes and things like that 'cause she will just eat huge amounts at once.

NNAMDIHow well do Americans understand and relate to the notions of calories in their food and drink? Can you talk about that, Ben Caballero, and maybe also give Amy some advice for her niece?

CABALLEROSure. The issue of people being informed of how many calories are they consuming is -- there are two issues. One is simply civil rights, right to information. And in that I don't think there's much controversy that people should know what they are eating and have the information including calories. But the real question is from the many initiatives in action that we can have to reduce the risk of obesity in the population, how high to prioritize giving calorie information and hoping that this will make a dent on obesity.

CABALLEROAnd based on the evidence that I know I am rather skeptic on the possible effect simply because people's mind -- as was pointed out before -- is not linear. And simply having the calories doesn't have any direct effect on what is picked. It depends on the cost of the food. It depends on the opportunity, the income level of the individual, how high that food rates on their preference list and so on. So as part of a combined effort, including many other things, including portion size and particularly the quality of the food, I think calories information is one aspect.

CABALLEROAnd regarding the caller I think of course one needs to know the age and the circumstances. But in general as a general principle there are a number of groups -- support groups for parents and children that operate out of schools or other institutions that are great for getting children solidarity into learning and practicing how to eat well. So don't take all the responsibility simply on your shoulders, but realize that there are many, many children and families in your own circumstances out there.

NNAMDIAmy, thank you very much for your call. David Just, how well does the European system of giving foods a red, yellow, or green light work as opposed to simply telling people how many calories are in it?

JUSTIt actually has been shown to work pretty well. You know, of course any time you go to a very simple system like that where it communicates very little information, it's going to have some sort of quirks. I mean, people aren't going to behave as if they have all nutrition knowledge just for the red, green, or yellow, you know, traffic light symbol on the food. But they recognize when they see something that's red-lighted, I want to avoid this, and so they look for something in the same category that might have a yellow light or a green light.

JUSTI know they are moving back toward something a little more complicated over there, which may actually be a step in the wrong direction, although it does provide the consumer more information.

NNAMDIWell, the Affordable Care Act requires some restaurant chains to begin putting calorie counts on their menus. New York City has had a similar requirement since 2008, and the results seem to be mixed. Will this law change behavior? David, you seem to be suggesting probably not.

JUSTI don't expect it to change much behavior. As Ben said earlier, you know, there's a lot of evidence now looking in New York City, as well as in Seattle where they had these calories posted, that it doesn't have an impact on what people are buying on average, or consuming. There's one small group where they found it really did have an impact, and this will sound sort of funny, it's people who are dieting. People who are dieting actually ate more calories than they would have otherwise.

JUSTThey said what's going on here, well, when I go to a fast food restaurant and I'm on a diet, I'm already off my diet, and the calories start to mean something else to me at that point than they would have otherwise. But it's, you know, as simple as calories may seem, people don't use them in the moment. In the moment, people are tempted by the smell of the food and, you know, the really high fat and sugar type items, and they forget about the calories. They stop thinking.

NNAMDIBen Caballero?

CABALLEROOne positive development, just to say something positive about posting the calories, if we start with young children in school, we can really educate children on a very important concept that in general we don't have which is energy density. That is, that if you have a food of certain volume in your plate, the calories can vary tremendously, so we need to understand how many calories in different type of foods, and if we use the calorie information in school and in other setting to practically educate our children the difference between 10 grams of ice cream, and 10 grams flavors, I think it's not just the taste of the one you like and the other you don't like, but the amount of calories that you are putting in your body is very different.

NNAMDIWe got this email from Cindy is Charlestown, West Va., David Just. Cindy says, "If you want to change human behavior, aim for the pocketbook. The pricing of drinks, not only sugary sodas, but coffee and other beverages too, only encourages people to buy the larger sizes. If an eight-ounce drink were priced at one-fourth of the price of a 32-ounce drink, or if 16-ounce drink were priced at the half the price of the 32-ounce drink, consumers would be more likely to choose the smaller size. However, the large drinks are the bargain and money talks."

NNAMDIGetting back to what Ben Caballero said earlier about we're the ones -- or businesses are the ones who push consumers in that direction, and your suggestion that businesses might be the ones who can push them back, David?

JUSTSo I agree. I think there's some limits to what we can do in terms of the pricing options, but really what drove the larger soda sizes to begin with was people wanting to get a good deal, and, you know, wanting to be able to load up for the beginning of the day, take it to work and nurse it all day, and if the smaller packages are priced so that it's cheaper for you to buy, you know, your whole day's worth of drink in those smaller packages, well, they'll take the smaller packages, and they'll chose it. And then you can start to invoke some of our research about the package size, right?

JUSTAnd that smaller package size in that case where they're not fighting against it, and it's not really the focal point of everything they're doing, might actually get people to drink a little bit less.

NNAMDIGot to take a short break. When we come back, we'll continue our conversation on legislating how much we eat, but you can still call us at 800-433-8850. If restaurants listed the calorie count for each item on the menu, how would that influence what you order? 800-433-8850. I'm Kojo Nnamdi.

NNAMDIWe're discussing legislating how much we eat with Ben Caballero. He's a professor of pediatrics and nutrition at the School of Medicine and Public Health at Johns Hopkins University and David Just, he's a professor of economics and director of the Center on Behavioral Economics and Child Nutrition Programs at Cornell University. Ben, you wanted to say something about the pricing.

CABALLEROYes. Clearly, pricing and value is something that one can manipulate for good purpose, but it doesn't make sense just to increase the price of bad food. This brings the issue of food quality and availability. What we want is the quality of the food to improve at the reasonable value for consumers. If we have just the same inadequate food that we have in many segments of society, but just up the price, I don't think that will be a solution.

NNAMDIDavid Just, portion size has surged in recent years. The average fast food soda is seven times bigger than it was in the 1950s, even a bagel, twice as big as it was in the 1970s. What does your research show about how people react to new norms of bigger portion size?

JUSTWell, so when they're presented as the norm, right, people tend to try and focus in on that norm and consume up to that norm. So if I go to, you know, the local 7-11 now, and every soda that's for sale is 21 ounces, I start to think about 21 ounces as the normal amount I should consume, and I start consuming something close to that amount. Unless I'm, you know, somebody who's rather odd and really focused in on nutrition, that's what's gonna end up happening. Same thing with that bagel.

JUSTAnd so if the social norms change, if they, you know, if we can find ways to sort of lead people to believe the social norm is a much smaller size, they're gonna start eating less than they are now...

NNAMDIBen...

JUST...and that's really where the possibilities are.

NNAMDIBen, adults seem to have taken to heart what we learned as children, clean your plate, but we're not born with that instinct apparently. How do young children eat differently from adults?

CABALLEROWell, that's a great question, and certainly some clever investigators did test that years ago, and clearly we are born -- and babies for example, if you offer a baby different volumes of formula in a bottle, the baby consumes only enough and the same quantity regardless of the density, regardless of the volume, and a three, four year old still has a capacity to consume the same even if you offer them different volumes of food.

NNAMDIThey stop when they're full.

CABALLEROThey stop at the same volume. This had been (word?) they're sort of very nice studies on this. But beyond five, six years of age, children progressively lose that capacity and certainly adolescents and adults, we are not really able to control by calories consumed, but we just consume whatever is on the plate.

NNAMDIOnto the telephones again. We go now to Kat in Manassas, Va. Kat, you're on the air. Go ahead, please.

KATHi. Yes. I just wanted to say like not only has the extra large gotten bigger over time, but the small and the mediums have as well, and I agree that putting a cap on the extra large would anger people. But when I order a medium, they just keep getting bigger, and even like when you go to the movies, you order a small and it's a bucket of soda. I feel like putting a cap on the extra large wouldn't be a good idea, but perhaps putting a cap on the mediums and smalls so that if you just want an average amount, a small amount, you can get that without feeling like you're going to drink all of it.

NNAMDIHow do we get that horse back in the barn, David Just?

JUSTWell, actually that's not that bad a suggestion. We've got some research where we tried to look at how, you know, what we call a serving size affects how people eat, and despite the fact that you can -- you look at what you're eating, and you know exactly how big a, you know, plateful of spaghetti or whatever it is you're eating, if we call it a large portion, people leave more on their plate than if we call it a small portion, even though it's the same amount of food.

JUSTSo there might be some real wisdom in sort of putting guidelines out there as to this is what we should call a medium, right? Or this is what we should call a small. I -- you run into this all the time. I was this last weekend with my child out ordering soft serve ice cream, and I ordered the small, and it was just gigantic. How do you, you know, and you're going to eat it as soon as they give it to you.

JUSTI'll start with you on this, Ben Caballero. Who bears the responsibility for policing portion size, lawmakers, food companies, individuals?

CABALLEROWell, I think it's a combination. It's not only individuals, because if you put an individual in a grocery store where there are a hundred foods and 95 are unhealthy, you cannot blame that individual completely for eating unhealthy. You need to make healthier food more available, and at a reasonable price, and then expect that this individual will have the education, the preference in order to select the right food. But right now, particularly lower socioeconomic level populations don't have the food choices that we think would be the optimal to feed themselves.

CABALLEROSo there I think a combination of the forces of the free market, but also legislation as it is in many other areas need to be put in place.

NNAMDIDavid Just, regardless of legal measures designed to target excess calories, what are some of the. well, subliminal tactics that can also be effective, like using smaller plates, smaller serving spoons?

JUSTRight. So we find, you know, in your own home, you can take a whole bunch of different steps that will help you to try and cut back on what you're eating, and the very first thing to do is to take your large plates and put them away and go get some smaller plates, because you can reduce what you're eating by about a third over, you know, basically immediately. As soon as you start using these, you'll start looking at the smaller plate as the norm, right? And you're gonna end up putting less on your plate than you would otherwise, and eating less than you would otherwise.

JUSTThere are also a couple of other pretty quick things you can do. One is making sure the bad foods are not visible, right? Just by having those foods somewhere up in a shelf where they're a little bit less accessible and you're not gonna be reminded all the time about them, that can, you know, we find you can take off about 20 pounds over time by not having those visible, by maybe having fruit or vegetables or something else that's healthy and convenient there.

NNAMDIBack to the telephones now. Here is Bryan in Fairfax, Va. Bryan, your turn.

BRYANHey guys, how you doing today?

NNAMDIDoing well.

BRYANExcellent. Hey, I apologize because my question -- or my statement is not going to be framed that well, but as I ramble on you'll get the point. The whole thing about portion sizes when you go out to eat with regards to a restaurant, they create these large barrels of pasta or rice dishes and all that because they can then charge more. If you had the smaller -- because they have to make a certain amount per each table, you know, guest comes through. So they increase the size, increase the cost, but it's not costing them more to make. Do you understand my point?

NNAMDIYes, I do.

BRYANAnd, you know, so unless the restaurants willing to make less money, or the consumer is willing to pay more money for that smaller size, it will just keep on going.

NNAMDIBusinesses will tell you that the true price of soda is the cup, not the soda, that it really doesn't cost that much more for the soda. David, you work with a lot of school cafeterias. How have you used impulse purchases at the cash register to push healthier food, and how can adults adapt that practice at home?

JUSTWell, so similar to what I was just talking about with having those fruits and vegetables visible, whatever food is visible, you start to -- it does what's called priming you. You look at it, and you start to get a taste for it, right? Now, it's probably not gonna make somebody who hates apples suddenly eat apples, but if you take, you know, in a school cafeteria, you right next to the cash register have a beautiful bowl full of apples and oranges or other fruit that, you know, kids like, generally, you have it sitting there, it will increase the number of kids taking it by about a hundred percent.

JUSTIt virtually doubles the amount of fruit consumed when you do this, and it's the same principles they're using in the stores, right? I mean, they put the candy bars right there by the cash register. All these other things that we are likely to impulse buy, because when you're right by the cash register, the line slows down and you're sitting there and you're staring at it, and eventually you start to want it, right? Same thing can work for healthy foods. It's not the exclusive area of -- or domain of unhealthy foods.

NNAMDIHow can we, Ben Caballero, push businesses in the direction of offering smaller servings, smaller plates, and the like?

CABALLEROI think there are consumer groups that are aware of these professional societies dealing with health and obesity in particular that are trying to group together and create a national movement explaining the three or four priorities that we all would like to see happening, and one of those is a reformulation of many products in order to make them different. And we already can see for example in the supermarket that there are smaller sizes of soft drinks for example.

CABALLEROSo as these products appear, then it's our responsibility to make people consume them, and I would add as a pediatrician that parents have a critical role in shaping some of the food preferences early on. It is not possible to ask your child not to consume an unhealthy food while you have it around the house or you consume it yourself. So I think parental guidance is one critical step to start this change.

NNAMDIDavid Just, we just have about 30 seconds. What incentives might encourage food companies to change the calorie count and the food and drinks they sell?

JUSTActually, I think the profit motive can work well. Now, they may need a little bit of guidance from government and other industry, but, you know, simply asking somebody in the lunch line would you be willing to forego the side and save yourself X number of calories, oftentimes actually works and people are willing to pay the same amount for less food. But it's got to be something that, you know, that the industry wants to do and do it for their own reasons.

NNAMDIDavid Just, he's a professor of economics and director of the Center on Behavioral Economics and Child Nutrition Programs at Cornell University. Thank you for joining us.

JUSTThank you.

NNAMDIBen Caballero is a professor of pediatrics and nutrition at the School of Medicine and Public Health at Johns Hopkins University. Thank you for joining us.

CABALLEROThank you also.

NNAMDI"The Kojo Nnamdi Show" is produced by Brendan Sweeney, Michael Martinez, Ingalisa Schrobsdorff and Tayla Burney, with assistance from Kathy Goldgeier and Elizabeth Weinstein. The managing producer is Diane Vogel. The engineer is Tobey "The Master" Schreiner. Natalie Yuravlivker is on the phones. Podcasts of all shows, audio archives, CDs and free transcripts are available at our website, kojoshow.org. Thank you all for listening. I'm Kojo Nnamdi.