Imagine you’re a young mother who sends her 7-year-old daughter to visit her grandparents along with cautionary suggestions about what the child will and won’t eat. Suppose what happens when eggplant — which is most definitely not on the she’ll-eat-this list — is the main course for dinner along with salad and herbs the child and her grandfather picked from a kitchen garden.

But some important details before you guess: Dinner was served at the dining room table, which was set with china, silver, crystal, cloth napkins and candles with some jazz playing in the background.

It turns out that the little girl ate almost everything on her plate. After dinner, she excitedly called her mother to tell her about her experience. "You would never eat that at home!" her mother said. "That’s because you don’t know how to feed me!" her daughter replied.

Why You Eat What You Eat cover, by Rachel HerzThis "out-of-the-mouths-of-babes" story made Rachel Herz laugh. The author of "Why You Eat What You Eat: The Science behind Our Relationship With Food" knows it's all to true.

"We eat with our eyes first," said Herz, a neuroscientist who specializes in perception and emotion and who teaches classes on the senses and psychology at Brown University and Boston College. "The way food is presented can really influence how much people are going to like it and how much value they think it has." Offering children varied diets with a wide range of food can start them on a lifelong journey of making healthy decisions about food, added Herz. In fact, this journey can even start in the womb when a fetus is exposed to food aromatics in the amniotic fluid from the mother.

These are just a few of the interesting facts behind the sensory, psychological and neuroscientific factors that influence our relationship with food, all of which Herz discusses in her book. Herz supports all these findings on a foundation of science — which includes a few things that surprised even her. One of those will probably come as a surprise to ecologically minded shoppers. People who bring reusable bags to the grocery tend to buy more cookies and treats than those who take food purchases home in the grocery store’s plastic bags.

But don’t let the science aspect of the book fool you into thinking that it will read like a textbook. Herz is a storyteller who uses the experiences of real people to support various findings into our relationship with food.

Herz spoke with MNN about her book and how her work can help just about anyone.

The book explores what you call a relationship that each of us has with food and how food affects the relationship we have with ourselves and other people. We’re guessing many people don’t think of eating and food as a 'relationship.' Could you explain what you mean by this?

I think that most people assume that food is just food. It’s like this stimulus in front of them, and they respond to it in kind of a pure way. But that’s not the case at all. We have very complex interactions with food. This has to do with all kinds of factors that are in the world around us, beginning with the basics of our senses and how our eyes and our ears and nose and our mouth tell us information about the food. It has to do with the environment we are in. It has to do with our own moods and emotions and feelings and personality. And, so, this whole complex dance is the relationship. My goal in writing this book was to give people the knowledge of all the factors that go into their relationship with food so they feel that they are able to control their experience of food rather than feeling like food is controlling them.

Rachel HerzThe book makes the point that to understand our relationship with food, we need to know something of the science behind that relationship. You explain the science in a very readable way. What are some of the fun facts behind this science?

There’s just a lot of things that I think people don’t quite realize in terms of what is going on from a scientific perspective. One of the topics I cover is how foods that we are familiar with actually make us feel more full and more satisfied than ones that we are unfamiliar with — and that’s regardless of their caloric content. There is a fair bit of research that shows that the calories in the food are not what’s driving our feelings of fullness, satisfaction and hunger. It’s what we think about the food. Also, when we think a food has more calories — whether it does or doesn’t — it makes us feel more satiated and we eat less of it. We also have a more intense metabolic reaction to it. So, in fact, we burn more calories when we think we are eating something that has high calories regardless of the real caloric content. The same thing goes for food that we think has low calories. In that case, our metabolism can stall. It’s not like there’s this fact of nature out there that is food and we respond to it in a logical, consistent and objective way. Instead, there are all kinds of features about the environment and our own perceptions that are guiding, shaping and dictating our experience of food and changing things in shocking ways.

Are there any specifics you could share to illustrate this example?

I give an anecdote in my book about the father of a friend when I was growing up who never felt full unless he ate rice with his meals — regardless of how many calories were in the food he was eating. I think the point would be that from a practical perspective, if you could find something that you could add to your meals that makes you feel like it’s the end of the meal — especially something that’s healthy and not exorbitant in calories — that would be useful. I think nuts are a good example of this because they are high in fiber, protein and fat, and fat is something that in and of itself is very filling. You could, let’s say, after dinner have a few walnuts or after lunch have some walnuts as a signal that the meal was over and feel satisfied. Or, if you want to go on the lower calorie end of things, you could choose raw carrots. But, whatever it is, just understand that we can sometimes be fooled into assuming that if we are eating something not in our regular food repertoire that when the meal is over we haven’t reached satiety, when in fact we have.

Where does this come from? Is it genetic? Is it environmental?

It’s totally environmental. There’s nothing genetic about feeling that rice makes you full or cashews don’t make you full. It has to do with how our experience with food dictates our perceptions of food. The more familiar we are with something, the more there is a habit involved in our consumption, the more that we feel like we have reached an end goal. We don’t normally eat constantly throughout the day. Instead, we eat in bouts and have snacks between meals. So, we need to have some sort of cue from what we are eating to understand our level of fullness. That’s because we often don’t notice when our bodies give us physiological signals that we have had enough to eat, and we look to external cues to give us those signals. Therefore, preparing a few such foods to give us those 'I am full' clues can be helpful.

Have marketers figured this out?

Packages of potato chips on a shelf in a Toronto store. We seem to be more attracted to foods when we see there's lots there to eat. (Photo: ValeStock/Shutterstock)

I don’t know exactly how much marketers know because I am not in that business. I think they certainly do understand a lot of the mechanisms that make us buy stuff. One of the things I think is interesting is the number of iterations of things we see on a package. A package of potato chips, for example, that just showed one potato chip, would look a lot less inviting than a package showing many potato chips. Seeing lots of things is more appealing. We are more attracted to foods where there are multiple visual iterations, especially for things that we are going to be eating more than one of — like potato chips! I think marketers understand that. I think they understand how the language of advertising is very important and that the way one talks about food can have a big impact. In fact, I reviewed some studies by marketing researchers showing that if you talk about the multi-sensory aspects of something you are eating, it has more impact on the consumer than if you just talk about the taste. So, if you talk about the crunch and the aroma and the look of the food, it is more appetizing and appealing to consumers than just saying the food tastes good. Marketers certainly know a lot about manipulating children as well and how to encourage them to ask their parents to buy certain foods. Advertising food to kids on TV can have detrimental outcomes, since they are more susceptible to these visual lures than adults. Parents have to be careful that they don’t let their children succumb to this seduction. But, anyone watching TV or screens who sees food advertising will want to eat treats, even if the advertising is about healthy food.

Is it a bad idea to take your children when you go grocery shopping?

It’s a bad idea if you are going to let your children rule the roost! It’s good if the parents are being responsible and showing their children what is good food and why it’s good — for example, why we are going to choose a cereal that doesn’t have lots of sugar. I think it depends on the relationship of the parent and the child and how much the parent is able or willing to be an educator rather than giving in to the wishes of their child and the capability of the child to understand what their parent is trying to explain. One problem is that most of the time parents don’t have a lot of time. They can’t just go on field trips to the grocery store to explain what is good and why we need to buy fruits and vegetables and why we don’t want to buy cereal with tons of sugar, or lots of chips and cookies. On some level, it might be easiest for parents who are making responsible food choices to just say this is what we have in the house and this is what you are going to eat.

Speaking of grocery stores, many environmentally conscious people are taking reusable bags to groceries to avoid using the store’s plastic bags. But, you write that using reusable bags encourages us to buy more chips and cookies. How does this work?

Fruits and vegetables in a reusable grocery bag. This is how people think they stuff their reusable grocery bags. This is not how it often turns out. (Photo: Markus Mainka/Shutterstock)

This is specifically the case when the grocery store isn’t imposing a penalty if you don’t bring your own bag and you are being virtuous of your own free will. In that case, people are more likely to treat themselves after they feel like they have treated Mother Nature well. This was the finding of a big market research study conducted in California. The data were collected about a decade ago, and now grocery stores in California require you to being your own bag. However, in places where you still aren’t penalized for not bringing your own bag, the findings certainly apply. When they bring their own bags freely, people tend to treat themselves because they feel like they have done a good deed and deserve a little reward. That is one of the findings that when I was doing research for my book really surprised me. I thought, ‘Wow! But, when I thought back on it, I realized that when I shop in certain stores, I am more inclined to do that, too! Another study involved radio frequency tags that were put on grocery carts so that researchers could tell where people were shopping. This study found that after people bought healthy food, like grapefruit and kale, the next place they went was either the ice cream aisle or the alcohol section. So, again, this shows how we are extremely good at balancing our virtues with our vices whether we realize it or not! The problem with our balancing acts is that we make miscalculations. What’s also interesting is that organic labeling can make people fall into an unhealthy trap. When we see the word "organic," especially if we are more likely to be environmentally conscientious or believe that we are actively promoting our health by choosing organic, we eat more of the organic food than we would if it weren’t labeled "organic" — even when the organic food is a treat such as cookies. Organic cookies often have as many calories and as much sugar as conventional cookies. Something else that I found very surprising is that people will feel that it is OK to forgo working out after eating an organic treat. They think, "I just had an organic cookie, and therefore I don’t need to do something else that actively promotes my health, like working out." People need to be aware that when it comes to organic treats, the health benefits stop at a certain point.

While we're talking about food choices, are each of us genetically programmed to make certain food choices? If so, are some of us 'doomed' to crave sweets, or can we change our fate?

We are doomed! There is a genetic basis to having a sweet tooth. There’s also a genetic basis to being sensitive to very bitter-tasting foods. This can have negative health consequences because not eating bitter leafy greens can increase the potential to develop certain cancers. People who avoid bitter foods are known as "supertasters." This is due to genetics and leads, among other things, to having a more extreme aversion to bitter-tasting compounds than people who are "non-tasters," which is also due to one’s genetics. The good thing about the tendency to avoid bitter taste is that in nature, bitter tends to signal poison. But bitter doesn’t mean a food is poisonous 100 percent of the time — especially when it comes to antioxidant vegetables that are purple and dark green, a lot of which are quite bitter. Some studies have shown a link between being a supertaster and certain forms of cancer. At the same time, regarding my point that knowledge is power, if you know you are a supertaster and you’re not eating Brussels sprouts or kale or other healthy bitter vegetables, there are things you can do to improve the taste of those foods. One of them is to add salt, which blocks bitter taste receptors. There are also different ways to prepare food that can help enhance the sweetness. Roasting is one way since caramelizing brings out more sweetness. With regard to a special liking for sweets, just because you have a sweet tooth doesn’t mean you have to eat foods that are full of sugar. There is something called free will! I think being aware of your predilections can help you say, "Well, OK, even though I get a lot of pleasure out of eating sweets, I don’t have to eat them all the time." You might even get more pleasure by saving the times you do for special occasions or when you really feel you need to, so that you are more engaged with the pleasure of eating. Just knowing the kind of person you are can help you manage your cravings.

You write that our tastes and our emotions are intertwined. How does that work?

Back to sweet taste. It turns out that people who have a sweet tooth are perceived by other people as being sweeter and, in fact, it’s true! They actually are a little bit sweeter to other people. So, there is truth to the saying that sweetness makes you sweet. In fact, eating something sweet can make anyone a little nicer in the moment, even if they don’t have a sweet tooth. That’s why it’s an effective strategy if you are going to host an important meeting or do something where you may want people to be more aligned with you to bring donuts, brownies or cookies to the meeting. This usually will have a positive effect. Indeed, this research made me think back to when I was in graduate school and there was one person who would bring amazing home-baked treats to our meetings. But after she graduated and there were no more sweets people were never in as good a mood as when she was there. The other interesting thing that has been shown is that there is a correlation between a preference for really spicy food and being what psychologists refer to as a "sensation seeker" — people who like to do things like ride roller coasters, go to horror movies and maybe try sky diving. People who like a lot of stimulation in the world also like a lot of stimulation in their mouths. An example is liking hot peppers. But even if you make a point of riding roller coasters, if you’re a supertaster you’re unlikely to enter a habanero eating contest because the peppers are going to taste too painfully hot. Everything, not just bitter things, tastes more extreme in the mouth of a supertaster.

There has been a lot of reporting in the mainstream media about food that’s good for us and food that’s bad for us. Any myths we should be aware of?

There is a real problem with both nutritional and medical advice because it changes almost by the minute. When I was doing research for the book, I subscribed to various news feeds about nutrition and obesity. But I came to a point where I thought what I was reading was ridiculous. Every day or so I would get this list that was inconsistent and changing. So, I said forget it, I’m just going to go and find basic research and take more of a 20,000-foot view. What you find when you take a larger perspective is that ultimately there are a lot myths about food. One of the latest is about salt — a new villain in the equation. The American Heart Association recommends a certain level of salt to maintain a healthy diet. But a large study recently showed that people who ate more salt than was recommended — but not too much salt — were in fact healthier than people who were eating the lower recommended amount. The point is to take everything with a grain of salt! And to use common sense. I would not follow the constantly changing guidelines on the latest and greatest thing you should or shouldn’t eat. I would think about it from a more common sense perspective. Now, there are certain things such as trans fats that are not good for you because of the chemical process that takes place to create those kinds of fats. And, in general, advice that heavily processed foods aren’t good for you is on the mark. I expect these kinds of things to be true 10 years from now as well. But, regarding all the latest-greatest diet information, I would take a step back from that unless you know you have a physical condition where you shouldn’t eat salt or certain other things. If you’re an average healthy person, just use common sense, and eat what you want in moderation.

A plate of mature cheeses and grapes Which of these grapes will taste sweeter if your eyes are closed? (Photo: Goode Imaging/Shutterstock)

Was there anything else in your research that surprised you?

I think it is very interesting that we eat with our eyes first. The way food is presented can really influence how much someone is going to like it and how much value they think it has. Another, is how visual cues influence how many calories we think something has. Take, for example, a super-duper sandwich that has a lot of calories because there are layers of bacon and meat and cheese. Put a sprig of parsley and a celery stick beside it and people will think the sandwich has fewer calories than if it was just presented by itself. The context that food is in is very important. People need to be aware of all the different things that are going into their belief system with respect to food and how their expectations may be altering their perception. Another example is how the color red makes us think things are sweeter and the color green can make us think things taste more sour — although when fruit is riper it tends to be more red than green, this isn’t always the case. Take the case of red and green grapes. Let’s assume they have equal sugar content. If you closed your eyes and ate those grapes, you would think they tasted equally sweet. But, if you ate them with your eyes open you would tend to think the green grapes were more sour. So, knowing all the factors that affect our senses and our mind when it comes to food is really important.

Can you sum up how 'Why You Eat What You Eat' can contribute to responsible living?

In a nutshell, if you understand all the things that go into your relationship with food, you can make much more responsible choices for yourself as well as for your family. As some other examples, there are all kinds of ways that music and sounds influence the way we eat and our perception of food, how the number of people we are eating with alters how much we eat, and how the mood we’re in can change how food tastes. There are also things that happen in the grocery store, and how health and organic labeling can manipulate us in ways that aren’t always healthy or responsible. Knowing all of this will give you the power to take control of how you eat and what you eat and make your relationship and experience with food better.

For young families with children, are there lifelong benefits for children who experience this growing up?

I am not a developmental psychologist, but, I do know that parents who eat a more varied diet, who present to their children a more wide range of food and cuisine will have children who are more accepting of different foods. This ultimately leads to a healthier diet and greater health overall. Exposure to different flavors can even start before a child is born. If an expectant mother eats a lot different foods with a lot of different flavors, she will have a baby who has already been exposed to the aromatics of these foods and is therefore going to be more predisposed to different kinds of food flavors. The more parents serve novel foods and expose their children to as much variety as possible, the more likely their children are to make healthy food choices when they can start making their own decisions. So, even if you never served roasted beets at home but served a lot other different kinds of vegetables, a child who from this food environment when presented with roasted beets for the first time is more likely to try them than a child who came from a home where there was not a lot of variety in the kinds of food that were offered. One of the take-home messages from my book is moderation and variation. I want everyone to love food. I don’t want people to feel guilty when they eat certain foods. Eat anything you want, but just not too much of it, and change it up so that there’s a lot of variety in your diet. That’s the best way to be healthy and happy with what you eat.

Inset photo of author Rachel Herz, courtesy Kathleen McCann

Why do you eat what you eat? It's complicated
Rachel Herz explains the science behind our relationship with the food we eat in her new book, "Why You Eat What You Eat."