Sometimes when we eat food, we know that we're not eating it because of the nutrition. Sometimes we're eating it because we like it, and somehow I would use the term we're addicted to it. So, let's come to talk about craving, and see how it's related to use of nutrients. And in fact at one point a French chemist pointed out that well, if you know all the food is made up of all these nutrients, minerals, vitamins and other things, so why can't we simply take pills? And therefore we would be able to satisfy our need for biological function. And yet we know that we are not eating food simply because of the nutrients or the energy because we want something more. What's that something more? Now, we know that human, we are the living creatures. We have a lot of very sophisticated sensory organs associated with us. We have our ear. We can hear very specific sound wave. We have our eye, we can see all the different kind of color. We have our tongue, we have our nose, we can smell, we can taste. We can sense the world around us. Why do we need all these? Because in a way, we want to see how the world is like, and food is certainly one aspect that we want to see the world. So we want to have all the senses being stimulated. And when they're stimulated we feel satisfied. Now, so therefore what I want to point out is that craving. I call it sometimes some level of addiction. Is not synonymous with the so-called increased eating. It's not just you're eating a lot. Craving means that there are two aspects of it. We have a very strong or intense desire. We want to eat something, we love it. And we are in love with a particular food, a very specific one. So in all these, in fact, we don't need to be hungry. We can be totally in, after a meal we're full, and still we want to eat it. That's what we call craving, and it is a very subjective experience because we are after a particular taste. Now let me illustrate that to you. Many of you probably have the experience. Well, chocolate. How many of you like chocolate? Raise your hand. Craving research, in fact, they find that a lot of episodes of so-called craving in human beings is associated with chocolate. How come we like to crave chocolate so much? Here it goes. Let me try to analyze a little bit for you. Well, many of you are in love and we know that when we are in love we're going through three different stages. The first stage we call the falling in love stage. And in fact chemically we say that is the amphetamine stage. Meaning that actually our nervous system is somehow stimulated by amphetamine, which give you the sense of satisfaction, euphoric feeling. And when you're falling in love, at this stage, you can't think logically. So that's what happens. When you get beyond that we call that the lasting love stage, which we call the endorphin stage. It's just like the people who go running, jogging. They like it, they run the marathon. They feel very good after running. They don't feel tired, and the simply they feel that they are very intimate with each other. They become very dependable, they want to be with each other. And the final stage is called the bonding stage, which we say that is the oxytocin stage. That's the level of oxytocin that gives us arousal so that we feel very relaxed. We like to be with each other and we feel that we are bonded. So, think about that. Under all these stages, you are in love. What that's to do with chocolate? In fact, in chocolate we have this compound called phenyl ethylamine. Some of them, they have ananadamide, similar to something like the marijuana. In a way it is anti-depressant. So, what it is? It's this compound, in fact they can be addictive. What did they do, they act on our nervous system in the reward center there is a place which we called almond body, when they're being stimulated we feel very satisfied, we feel we want it. An what happen is, when you eating chocolate, you feel rewarded, don't you feel good? Now you're not eating the chocolate because you want to have the sugar, not because you want to have the milk. It's because you want to feel rewarded. So that's why we develop this craving behavior. So therefore, a lot of times we want to feel rewarded. And if you looked around all these factors that affect how we like one food or the other, the mood, the name of the dishes, the environment, a plate of flavor. That gives you hedonic responses or the kind of exposure. What are they doing? They're trying to give you a sense of reward. And when they are all coupled together, we associate that with you are in a very comfortable space. Very satisfied. And so that's why you like it. You will see that as a rewarding process. So you love it. And so you go for the food. So therefore, we say that mood and food sometimes they are so certain. When you are in a happy mood, sometimes we eat more food, when we eat healthy for two. And when you're in a sad mood, sometimes you just like a junk, you like put in a lot of things but not less assured because that you love that particular of food. So that's how mood and food are being associated. The other element is that, well sometimes let's look at the menu. When I show you this menu A, it clearly tells you what kind of foods they are. Red beans with rice, seafood filet with chicken, grilled chicken. So plainly describing exactly what that food is. Do you see this kind of menu very often in the restaurant? No. Let's look at that. Most likely in the restaurant you'll see some menu like the one on the right, which is traditional Cajun red beans with rice. Succulent Italian seafood filet or you have home-style chicken Parmesan. So all these, what is it? All the circled words, they are adjective words that describe what the food is like and it give you some sort like imagination to what kind of things they are. Succulent homestyle, does it remind you of something? Now, so therefore with all these description, it kind of like make you feel that they are better. So one example is, we call that the magic of the menu. When you have the food, you have all this descriptive name. And usually with the descriptive name, they are rated better. Why? Because with all these description it entices you to buy the food. They link the food with some of the appealing images, experience. And sometimes they need you to expect something that you remember that you have experienced in the past. Now, so all this makes you feel that the food's quality is better. Now a lot of this label in fact try to stimulate you stop thinking about some geographical label. It represents some stuff like a culture whether is Korean food, Vietnamese food, Chinese food, Italian food or French food. It tells you some type of a style, sometimes it gives you a nostalgic label while telling you what traditional it is home style grandma cookie. So that reminds you of what is in your history. Sensory label, succulent want something taste good, it's delicious. And sometimes the brand, and because we've eaten something associated with a brand so whatever is produced by that particular brand name it must be good. So therefore it kind of gives you that perception, or in fact they are playing deception. So, also environmental factor it plays a very important role in the process. You remember that in a lot of restaurants that you go to, a lot of them they put a lot of attention on the decoration, the lighting. They want it to be very soft, very calm, quiet. It gives you a feeling that while all the waiter or waitress they are treating you very well, and they give you a good name of the dishes, describe it very well. All this creates a belief that the entire restaurant, they're simply catering for you. They have the dish especially prepared for you. Again, deception. And sometimes we use so-called the halo effect. They pair with you to tell you that, well, if they give you some good experience on one aspect. It give you a false expectation that everything else is all well prepared for you. So this particular kind of experience, we call it the halo effect. And so next time, when you go to a restaurant think hard and say, how they toy around with all these tactics. Now, in fact, what we need to understand is that if you look at our development, in fact how we perceive the whole world. In fact, we go through three different stages. The first stages is very primitive, how you taste something, you smell something, you see something. And after this learning process, in fact, something got etched into our brain and we remembered it. And the next stage is about language. And the next stage when you're in the college, then you go for all these higher cognitive function. But when we talk about food, mostly the sensors that we try to stimulate, is focusing on the ones which experienced by you at the early stage of your cognitive perception. So when exposed to this kind of food at early stage of our childhood. In fact, they give us a long lasting memory and we call that, in fact, it's called conditioned learning. You kind of associate some of the culture, some kind of food with certain feeling. And it is much easier to modify that when you are a child than when you are an adult. So what happens is that if a child is brought up in a particular culture, they tend to like the kind of food provided in that particular culture. Now, very easily I want to show a few example you remember the one you called movies? You like to have popcorn why? Because when you were young when you go to movies, you always carry the popcorn or a soft drink. Well, when do you have cookies? Usually it's the leisure time and you have nothing to do. You have a drink and you want to have cookies. So, it's a good time. A very extreme example. We say that, there are some World War II veterans that were somehow locked up in the war in China. And at that time they were eating Chinese food. So even though when they go back to the states, whenever they eat Chinese food, they remind them of the war time experience. So Chinese food tastes bad to them. Now, that's how we associate certain experiences with how we perceive whether the quality of the food is good or bad. So, another example that I can ask you to start thinking about. When you eat are particular meal and if there are some good stuff in it and there is some plain rice spaghetti or so which part would you going to take first? Do you finish all the spaghetti and rice and then eat all the sauce and meat and so? Or do you finish all the good stuff and then finish the rice later? That is experience because a lot of times it is related to in your childhood how you experience whether the food is readily available. And we find that, at least in the Chinese culture, we have a lot of people, if they have a lot of brothers and sister, they are short of food. The tendency is that they always go for the good stuff first and then they finish the rice later on. But, if in modern days, we have a lot of family where only one or two kid, they have plenty of food. Then usually, they don't have a such a preference whether they eat the rice first or eat all the other dishes first. Now, that tells you how the experience impacts our choice of them. Now, of course, all these so-called hedonic responses to the flavor and how are we going to interpret whether we like them or not? There's a lot of experience that comes into play. When we're eating food, foods by themselves have intrinsic value associated with them. For example, have you ever tried to give a baby something sweet? I believe that all babies like sweet. So if you give it to them, they all like it. Have you ever tried and give a baby something which is bitter, or something which is sour? Try it at home again if you have the opportunity. I'm sure that all of them would hate it. They would reject it. And the same thing, like trigeminal stimulation, what is it? It's like something in the Japanese food we have the wasabi, when you are cooking things with onion, well, you kind of feel like it's very pungent and you don't like the feeling. And so these are in general very unpleasant. How about salt? In fact, we are all longing for some minerals. So that we can have it incorporated to help us to function normally because of supply of the nutrients. So salty things we like them in general. So these are something called innate response. But of course, some of them can be acquired. That goes with your experience. Now, you can talk about all this hedonic responses. Yes, this pungent smell, the trigeminal stimulation, we can have it acquired. You remember that people like to eat Japanese sushi. And when you're eating sushi, you put wasabi in it. Why do we like it? Sometimes, people simply like that kind of experience that they almost like after eating a sushi, they almost like breakdown and cry. And but that feeling they like it and they become an acquired experience and from that point onward they would like a particular food. So what I want to conclude with that, is that we need to understand that whether we see food as good or bad there are few elements that we need to think about. One, some physical stimulation. How do they look, how do they sound, how do they feel, the texture, the taste and smell? These are very physical and a lot of the time there is a lateral association with nutrients and the quality of the food. All these come in becomes something very conscious. On the other hand, we say that a lot of time, whether we like a food or not, largely is dictated by whether we feel rewarding or not. And that can be easily influenced by, all this emotional association. Our conditional learning experience, and activating of the craving circuits that we want to be rewarded, and those act together on this end. And they're acting subconsciously detecting like whether we feel that it is good food or not good food, and of course we trigger this hypothalamus. The neuroendocrine organ that allows us to control whether we want to take in more food or we don't want to take in more food. And so, from this point on what I hope that you understand, in fact what we're talking about, as how we perceive food as having good quality or bad quality. It's not just by itself as good or bad, is the integration of all these together. Only when we can stimulate all these button appropriately, you'll be able to prepare a good dish that everybody likes.