Five minutes with… Dr Leah Maizey

Ella Rhodes asks the questions.

Academics at Cardiff University are set to launch a trial of a new weight-loss app called Restrain, based on cognitive control training. We spoke to Postdoctoral Research Fellow Dr Leah Maizey about the theory behind the app and what participants in the trial will experience.

Could you tell me how/why the Restrain project came about including the work and testing that led up to it and the theory behind it?
Lab-based studies have shown that training tasks that promote response inhibition or avoidance of specific food stimuli can reduce overeating (e.g. Lawrence et al., 2015, Appetite, 85, 91–103). It is thought that this training may boost cognitive control allowing better regulation of thoughts and actions to help avoid impulsive behaviours. While this work has shown promise, results do not always replicate and little is known about the mechanisms of how they work. The Restrain project takes these tasks out of the lab, delivering training via an app, to assess real-world benefits. The project aims to explore the suitability of cognitive control training (CCT) as a weight-loss tool by studying the success of numerous paradigms in the largest study of its kind. We want to establish which CCT methods work best and for whom.

Although we are testing many different CCT methods, the general aim is to break down the automatic associations people have with unhealthy foods and replace them with healthy foods. In theory, this should reduce unhealthy food consumption and promote weight loss.

What will participants in the trial experience while using the app?
Participants will be randomly assigned to one of six active (or one of 10 control) CCT groups. CCT methods include response inhibition, approach-avoidance, evaluative conditioning and implementation-intention-based training.

Each day participants will complete either training (a gamified version of a CCT exercise) or tasks and questionnaires designed to assess the outcomes of using the app (primarily weight and eating habits) or to assess individual differences that may influence the efficacy of training (including personality, willpower beliefs, mood and hunger). Using the app should take approximately 10 minutes per day.

As it is possible that personalised training may be more effective, participants are asked to select unhealthy foods that they would like to eat less of, and healthy foods that they would like to eat more, from a virtual supermarket.

How many participants are you hoping to recruit, when will the trial start and how long will it last?
We are hoping to recruit 48,000 participants from around the world, promoting the app through a bespoke website that we are creating, ScienceForge, and the media. The app is due to launch at the end of January or early February. Data will be collected for a minimum of one year.

If the trial is successful what will be the next steps for the project?
The second aim of the Restrain project is to further our understanding of the effects of CCT on brain neurophysiology and neurochemistry, and how individual neurobiological differences themselves may influence CCT outcomes. Our investigations will focus on neural networks known to mediate reward and emotion, and those presumed to exert top-down executive control. Using a combination of imaging and stimulation techniques, we aim to establish the role of white matter microstructure and functional connectivity between cortical and subcortical structures in food-related decision making. Furthermore, the role of excitatory and inhibitory neurotransmitters previously implicated in both response inhibition and approach-avoidance tendencies will also be explored.

- To find out more about the trial and to register your interest in taking part see

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