As an example of this thesis, she showed the development of smartphone use: While in 2011 30% of Americans owned a smartphone, this number had risen to 77 % in 2016. The development in Germany is similar. In the Konstanz Life Study, a cohort study in the area of Konstanz, 85% of those surveyed stated in 2016 that they had at least one mobile device. "This is an impressive development. As you can see in this example, a behaviour change can also occur at population level in a relatively short time - provided the change is appealing", said Renner.
The regular use of smartphones opens up new ways for nutrition surveys. Nutrition apps, which allow users to document and track their eating habits, also make it possible to collect data on the circumstances, where and when, food was consumed. The technical equipment of smartphones, such as GPS, can provide more information about eating habits. “Nutrition behaviour is more than what we eat and how much we eat," emphasizes Renner.
Population studies typically use food frequency questionnaires and 24-hour recalls to document dietary habits. However, these methods have limitations. "From my point of view, the main problem is not the motivation of people to list everything they have eaten, but the remembering. People often can't remember everything they ate the day before," says Renner.
This is where mobile data collection can help, for example by taking a picture of the food. In addition, the circumstances of how food gets to the mouth must also be considered. Here the five W's can help: What, when, where, with whom and how much (is eaten). This is an ambitious task that can be accomplished with mobile technology, explained Renner. She emphasized the importance of the timing of eating and presented data from population studies from France and the United States showing the impact timing can have on dietary behaviour. While people in France eat relatively synchronized at three times a day, people in the USA eat asynchronously throughout the day. One scientific hypothesis is that this synchronized eating is the reason why fewer people suffer from obesity in France compared to people in the US. Timing therefore seems to be a notable factor in the development of obesity, which should be further investigated with mobile technologies.
Text: Dr. Maike Gutmann, DGE (TA6)