An interview with Professor Wolfgang Ahrens | World Obesity Federation

An interview with Professor Wolfgang Ahrens

NewsAn interview with Professor Wolfgang Ahrens

In a recent interview, we talked with Prof Wolfgang Ahrens, professor of epidemiological methods at the faculty of mathematics and computer science of the University of Bremen, Germany.

He is Deputy Director of the Leibniz Institute for Prevention Research and Epidemiology - BIPS, and Project Coordinator for the Policy Evaluation Network (PEN). The project’s vision is to provide Europe with tools to identify, evaluate and benchmark policies designed to address physical inactivity, unhealthy diets, and sedentary behaviour while accounting directly or indirectly for existing health inequalities.

Building on our interview with Prof Knut-Inge Klepp, CO-CREATE Project Coordinator, we wanted to learn more about common themes and differences between the two partner projects, and their responses to the questions below.

What are the barriers to addressing childhood obesity in Europe?

There was a belief that by informing people about the right behaviours, they might change their ways. But we have learned that information alone does not work, at least not in the general population. Efforts were then made to encourage behaviour change at the population level, by asking people to improve their diet and physical activity levels. The effects were very small, and studies showed such activities were mostly unsustainable.

So now, we have learned that we need to consider upstream factors, we need to address the causes of the causes. That means considering environmental factors. The ‘environment’ refers to both, the physical and the social & legal environment. For example, the built environment shapes our physical activity behaviour; safety concerns are a major barrier that prevents parents from letting their children play outside.

National governments regularly launch initiatives to address childhood obesity which often fail, why do you think so many initiatives in this area are unsuccessful?  What has been learned from previous policy failures?

We cannot say whether they were failures or successes because they were not evaluated properly. In Germany for instance, there has been a lot of action without evaluation. Insufficient scientific evaluation of intervention measures about health outcomes has been a shortcoming of most of the programmes that have been launched. However, we can say that in the majority, these programmes have failed, because overall we have not been able to reverse the trends and reduce childhood obesity. In some countries, there has now been a plateau but not a reversal. So, one of the key learnings is that when we plan an intervention we should at the same time, plan for a rigid scientific evaluation of its effects. This will require a rethink for how governments support research, policy, and practice efforts to address obesity.

Are there any countries that you can highlight that have developed you know, something particularly innovative in terms of an intervention or policy?

Tax on sugar-sweetened beverages (SSBs) is being discussed everywhere, the UK and Mexico have made important moves in this area. Other countries in Europe like France, Hungary, Ireland, Norway, and Portugal have also implemented taxation measures. I think these are the kinds of policies we need to pursue. We have investigated this topic and reviewed studies. There is acceptance of such taxes in the general population if the revenues are returned, for example as a reduction in taxes on healthy foods.

In Ireland, they have a national physical activity plan which galvanises the effort of several government departments and agencies into one common goal – address the high levels of inactivity across the population. While this cross-sectoral effort is necessary to enhance childhood levels of physical activity and contribute to the prevention of childhood obesity, again no robust evaluation of the implementation and impact of this plan, which is government policy, has been undertaken. Without this knowledge, it is challenging to progress in an evidence-informed or evidence-based way.

Why do you think that childhood obesity prevalence across Europe is so varied?

The aetiology of childhood obesity is complex and so are the reasons for the variation across Europe.  In general, we see a higher prevalence in southern Europe as compared to the north. The reasons are many. We conducted a family cohort study in nine European countries, we were able to identify the main risk factors for childhood obesity that may explain some of the variations. One of the surprising results was the fact that, when we created a Mediterranean diet score, to classify dietary patterns in children, we saw the best adherence to this diet in Sweden, which also had the lowest prevalence of childhood obesity.

We observed that risk factors such as sleep, media consumption, physical activity levels, consumption of SSBs, and dietary patterns varied across countries alongside the prevalence of obesity. In one country, one factor can play a particular role but in other countries other factors are dominant. While there may be more mediating factors that we have not yet considered, I would say behavioural and lifestyle differences play a role as well as different value systems.

An example is The Netherlands where approximately 75% of children cycle to school and riding a bicycle is common practice because the infrastructure is designed to make cycling very easy to do. Compare that to 3% in Ireland: both countries have similar weather, but the infrastructure and cultural acceptability are vastly different. So, behaviours can be influenced by perceptions and cultural values. Such upstream factors should not be neglected.

How is the Policy Evaluation Network evaluating policy measures to promote a healthy diet and physical activity i.e., health-related behaviours in Europe?

At PEN we assess food nutrition and physical activity policies. We do this using the INFORMAS approach. This is where policies are benchmarked to assess how successfully they have been implemented to identify those that are promoting favourable food choices or increased levels of physical activity most effectively.

We also want to contribute to the improvement of policy evaluation by providing better data, but to do so we need to monitor a range of indicators of health status and health behaviour of the general population as well as the main drivers of health behaviours. So, to enable this we have established a network of major surveillance systems in Europe.

Another important aspect of our work is looking at equity. We have a workstream that considers whether policies are socially divisive.  Finally, we have also been working on developing concrete suggestions in some key areas, namely school physical activity and nutrition policies, mobility policies, and sugar taxation.

The PEN project is coming to an end in 2022. What do you aim to achieve by then, and beyond?

I hope to have developed a sustainable network of researchers, but also stakeholders who have developed an enhanced capacity for understanding how to evaluate and benchmark policy actions within their own country, but also across Europe and globally. I also hope that network members will continue to collaborate and develop effective policy measures. I expect that by the end we will have a better insight into what policies exist and a better understanding of their effectiveness, as well as new knowledge on the most appropriate research methods for studying policy impacts. We will hopefully be able to provide benchmarks so that countries can be compared. This will hopefully allow us to inform countries about where they can improve or where they are already doing well.

How has the cross-collaboration with the STOP, CO-CREATE, and JA Best-ReMAP projects strengthened your efforts to address childhood obesity in Europe?

We have been in a unique and fortunate position because the projects have been running simultaneously and it has facilitated a real exchange of ideas and methods. So, for instance, with our benchmarking process, we had limited resources and could not cover all of Europe. When we discovered the work that STOP was doing, we were able to harmonise the methodology and now we have twice as many countries involved as before. Also, the fact that CO-CREATE is doing similar work to us but with a different approach will allow us to learn from different methodologies and in the future to judge which is more useful or feasible in the long term.

PEN has raised awareness of the contribution of policy and the need for policymakers to be accountable, to have access to evidence of impact to encourage data-driven decision making. While we might not have all the evidence, PEN has contributed to broadening our understanding of how to gather this evidence in a rigid scientific and robust manner. With time and adequate resources, this evidence will accrue.

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