Population diets

How can scientists best help the population change their eating habits for the healthier?
20 February 2019

Interview with 

Martin White, Cambridge University


this is a picture of various fizzy drinks


What are the best strategies for helping a whole population alter their eating habits? Katie Haylor spoke to Martin White, a population health expert from Cambridge University. First up, Katie asked, what factors go into deciding what to eat in the first place?

Martin - One of the key things is that in the environment in which we exist, there are lots of cues that that influence our behaviours. You come out of your office and you're walking down a high street or something thinking what shall I have for lunch? There are lots of cues there that are saying to you “come into my store”, “come and buy my food”, marketing, advertising, the presence of different kinds of outlets. The price point will be an important consideration. You might have a budget in mind for your lunch.

Cultural factors as well. So you may have grown up with a particular diet, you may come from a particular culture, or there are maybe just things that you like and things that you don't like, but there are literally hundreds of different factors that affect us. But the environmental cues are really important.

Katie - There are already some behavioural interventions from a population level. Things like the Five a Day campaign I guess would be one. Can you give me a few more examples of ones that currently exist in the UK?

Martin - At a national level Public Health England has a range of things, so quite a lot of them are kind of those kind of marketing campaigns like Five a Day that you mentioned, Change for Life campaign and so on. That's about conveying information essentially.

Then they're involved in other activities that are more aimed at changing the food environment. There's a lot of activity within Public Health England at the moment working with the commercial food sector to see whether they can change the kinds of foods that are available, reducing portion sizes, reducing sugar content, reducing total number of calories and so on. So that's some of the work that's kind of going on in the background.

Another approach which is gaining some traction now is regulation. In 2018, we had introduced in the UK the first fiscal measure in relation to food so the soft drinks industry levy which is a levy on manufacturers and importers on sugary drinks, charging manufacturers a small amount for each litre of soft drink that they sell or import that contains high amounts of sugar, it's actually a two tier levy.

Katie - Is this the sugar tax?

Martin - It’s what's called the sugar tax, yeah. And the purpose of it was to persuade manufacturers to take sugar out of their drinks, to reduce the sugar content, so as to avoid paying the levy. So that's an example of a regulatory measure and it's the first of a number that I think we'll see in the UK in the future. The Childhood Obesity Plan which was published in June 2018 includes half a dozen or more different regulatory measures that involve things like restricting advertising and encouraging labelling within the food industry and so on.

Katie - You're assuming that it's going to be accessible to people, I guess. People need to be able to access that information. It needs to be in the right language. They need to be able to read, and so on and so forth. How accessible are current measures to encourage people to be healthier when it comes to food?

Martin - Yes that's a very good question and these interventions differ in terms of the extent to which they require active engagement of the individual in order for the intervention to work. And that's really important because the more active engagement an intervention requires, the less likely it is to be effective. But in particular, in people who have difficulty engaging with that kind of intervention.

So for example you mentioned food labels. For people to really interact with nutritional labels, they need to be literate. They also need to be numerate, and then they have to start making choices based on that information. Those characteristics are patterned socio-economically within the population. So poorer people are the most likely to have problems with literacy and so on. It is really important and in our research we've come to the conclusion that government needs to focus much more on what we call low agency interventions, so ones that don't require the individual to make these conscious choices.

Katie - The thing is, most of us know we're eating too much, despite knowing this we still hear about this looming obesity crisis. So just knowing isn't enough. What's going wrong?

Martin - You have to think about this as a system level problem. The most convincing explanation of the obesity crisis is that we have a system that is delivering too many calories to the population. That system is the commercial food system. This is a quite a big challenge because we're used to developing interventions that are aimed at persuading individuals to change their behaviour, but the behaviour we need to change here is that of the food industry. That's why the soft drinks industry levy is so well designed and so powerful because it's really aimed at changing behaviour within the commercial sector.

Katie - From the research that you've done, what kinds of strategies work, when it comes to introducing effective behaviour change, for the maximum amount of people?

Martin - At the moment we're busy evaluating the soft drinks industry levy, we haven't published any results yet but the results are looking very promising. So I think that kind of fiscal policy is going to be very effective. There's a range of other things we can do and I think that what we'll need is a whole range of different measures in order to actually make a real difference to obesity. There's talk of further restrictions on advertising of unhealthy foods, pushing those beyond 9pm, what's called the 9pm watershed. There’s talk of restrictions in the online advertising of food,  what we've seen is a dramatic rise in the online advertising of foods, alcohol, gambling and so on. The digital space is an entirely new space for marketing unhealthy commodities.

And then there are other kind of measures as well, other sorts of policy measures which can be helpful. We've had a series of regulations introduced in the UK about school food and I've been involved in evaluating those over the last 10 years, and what we find is that when you regulate the food that can be presented at a school lunch, the lunches become healthier. So when you introduce nutritional and food standards. That has a good impact. One of the interesting things we found is that it doesn't just have an impact on what kids eat at lunchtime, but it also has an impact on their total food consumption across the whole 24 hours.

Katie - So I'm guessing having interventions where effectively people don't really need to change their behaviour that much. Maybe that's the best option?

Martin - Yeah it's more about whether people have to make these very conscious choices and that requires some kind of effort to make that choice. But yeah if you can eliminate the choice element then that's the most effective way to go and that's exactly the principle of the soft drinks industry levy. It takes the decision out of ordinary people's hands and it just means that what's available on the shelves has less sugar in it.

Katie - Simple?

Martin - Simple, and a good thing! Individuals will always be responsible for their own choices. People will still make choices and there still will be lots of choices to make out there. But the important point is that the research shows that if we can make the environments healthier, then it makes those choices easier. In other words the healthier choices become the obvious and easier choices.


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