I'm delighted to welcome Yeeli Mui to our MOOC. Yeeli is a doctoral researcher from the Global Obesity Prevention Center at Johns Hopkins University in the United States who recently visited us in Melbourne, which is where I met her and heard about a very interesting focus of her doctoral studies which are really around obesity prevention in adolescence. Yeeli, it's great to see you again and thank you so much for joining our students. But perhaps to start with, we hear a lot about the importance of preventing obesity in young children. Why the focus on adolescence? Why is this important? >> Sure, so of course, preventing obesity in young children is important. However, during adolescence and into young adulthood there's a tremendous amount of growth that's taking place. So this refers to physical growth, cognitive growth, as well as emotional development, that really requires proper and a healthy diet to make sure that adequate development is taking place. And additionally, adolescents are also experiencing a gradual increase in independence. So this has to do with financial independence as well as making more decisions about where to go and what to eat. So the dietary behaviours that are established in adolescence can really set the stage for later adult years, so it's really important to make sure that we're setting young people on the right path. >> Terrific, and when it comes to obesity prevention, certainly in Australia we hear a lot about the importance of, if you like, individual factors. And there's been far more emphasis on those factors than on environmental factors. Yet we're increasingly aware of how obesogenic our environment has become. Can you tell us something about what environmental factors you think we really need to consider most when it comes to the question of preventing obesity and how we might do it? >> Right, so as we've seen over the last several decades, no country has successfully reversed the obesity epidemic. And so I think it's really, as you said, moving this field and looking at components beyond the individual that might influence those individual choices. So when we're talking about the environment, this can be divided up into a few subcategories. One of them is the physical activity environment. So as the name suggests, this relates to areas where physical activity might take place. So is there green space or parks available? Are there physical activity resources or space at schools for children? Are there gym facilities that are accessible to people? There's also what's called the built environment, and this relates to infrastructure in which we work, live and play. So this can refer to housing, to schools as well as to the food environment that's accessible to children in a given area. We can also think about the environment in terms of the social environment. In the literature that's looked at social environment and its impact on health, many have looked at socioeconomic status, the influence of racial disparities as well as neighbourhood quality and safety from crime. And we can also think about social environment in terms of a kid or youth's social networks, how our connections to people, and who people are connected to influence their health behaviours. >> So this is really pretty complex when you outline so many of those environmental factors. Thank you. Obviously many of us are interested in how we might reduce access to obesogenic foods and, I think like you've articulated, the range of environmental factors, I know that in terms of how we might think about access to food, there's a range of ways we can also think about that. Do you have a framework that you could share with us in terms of how you sort of divide up the thinking about access to obesogenic foods? >> Sure, so the WHO defines access as having adequate resources to obtain nutritious foods for a proper diet. And this happens to be one of the three pillars of food security, the others being food use and food availability. Now in terms of access, we can think about a few components of access. There's the actual geographical or physical access. Does one have the resources or ability to get to those food sources that have those nutritious foods available? Or can one walk there or is a car or some mode of transportation necessary to get there? There's also the issue of monetary access. If those food options are available and physically there, are they at a price point that's affordable for individuals, so that a child or family can afford the foods necessary for a nutritious diet? And there's also what I'll call cultural access. Are the food options available culturally appropriate? Do they meet the food preferences of the population? Now again, as you said, there are many layers to this and it is quite complex. But I think that depending on the population of interest, some of these components might be more or less important than others. >> Which is interesting, because within this MOOC generally on global adolescent health we have talked about, in a sense, financial barriers and the role of taxation in particular in potentially curbing adolescent access to tobacco and other drugs such as alcohol. And we've also described the example of obesity as we know that adolescents are particularly financially sensitive or cost sensitive. And we've talked in this MOOC about how Mexico is really the example of the country that's been the first to introduce what we can think of as, if you like, a soda tax. And I'm interested, do you have any data on whether there's evidence that it's working? We know it was really only introduced pretty recently in 2014. >> That's right. So Mexico was the first country to pass this nationwide tax on sugar-sweetened beverages. The law was passed in October of 2013 and implemented on January 1 of 2014. And so there have been preliminary studies completed, one by the University of North Carolina Chapel Hill in collaboration with the Mexican National Institute of Public Health. And what they've reported is that in that first year of that policy being passed, purchases declined by approximately 12%. And Coca-Cola sales data indicate also that sales declined in 2014 on average about four cans per capita among Mexican consumers. So we've seen from preliminary studies that there has been some positive impact so far of that tax. >> And are you aware of any other countries at the moment that are planning on introducing similar taxations on food? >> I think that there have been discussions. I don't think any other countries that I'm aware of have passed taxation on food. There have been some cities in the US that have explored zoning policies, so not allowing your more unhealthy food retailers or maybe fast food restaurants within certain zones, schools, for example, where you might find a lot of young people. But findings from those are still coming in and the impact are so inconclusive, so we're still waiting to see what happens. >> Watch this space, huh? >> Yeah. >> You said right at the start that there's been no country that's managed to curb this trend of increasing obesity rates. I know, though, in your own research you're really exploring some different methods, and have some thoughts, no doubt, about what could be done differently. Can you share some of that with our students? >> Sure, so as we talked about in the beginning, the field's slowly moving away from focusing primarily on individual causal factors. And we're trying to find ways to understand more comprehensively the food system and the complexity in the obesity problem. And so what we're doing at the Global Obesity Prevention Center is using methods in computational modelling. So you can imagine developing virtual environments where we can simulate, within the safety of the computer, certain changes in a food environment. And run the simulation model over time to see what the impact might be on adolescent obesity, for example. So I'll give you a little bit more of a specific example and sort of paint a picture. What we're doing - A specific project is called Virtual Population Obesity Prevention. For those in the audience, students who might be familiar with maybe Sim City, it's a virtual representation of a city. And so what we're doing is developing a computational model that involves virtual representations of residents in the city as well as all of the food sources, schools, homes and physical activity locations. And all of these components can be assigned characteristics. So the agents can be assigned characteristics such as age, race, ethnicity, height and weight, and also certain behavioural characteristics, where they might go to shop for foods, etc. And all of the virtual representations of food sources, for example, can also be assigned a characteristic. So you can imagine it's sort of this virtual environment where you can change different components, run the model and more comprehensively analyse how these impact might have effects on obesity. >> Wow, certainly sounds an exciting opportunity to, as you say, really explore how those different elements might come together in the layering effects of different environmental interventions. Sounds pretty exciting. We wish you well for your research, but thank you so much for joining our students today and sharing something of your expertise with us. Thanks, Yeeli. >> Thank you very much for having me.