Understanding eating topography: The key to reducing energy intake in humans?

According to the World Heath Organisation, obesity has more than doubled since 1980. Estimates suggest that obesity now affects around 1.5 billion people. This is worrying because the health and economic consequences are very clear. Obesity is a major risk factor for cardiovascular diseases, diabetes, and some cancers.
One of the key observations about obesity is that not everyone becomes obese, even when they live in the same community, or even the same family. This means that some people appear to be 'protected.' Obesity researchers are interested in understanding why this is the case because this protection may hold the key to an effective treatment, or even a way to prevent obesity in the first place.
For a long time, researchers and health professionals have suspected that obesity is associated with a particular eating style, eating quickly in particular. Indeed, it is sometimes said that we should chew our food several times in order to feel satisfied and to 'aid digestion.' Recently, researchers have begun to explore this idea systematically. The results are striking. For example, under controlled conditions, it would seem that eating at a slower rate produces both an increase in self-reported fullness and a reduction in meal size. Moreover, when we look at people across an entire country, we find that eating rate is a good predictor of bodyweight, even in large-scale studies. In 2010 researchers started to look at ways to reduce eating rate to see if this might be used to lower bodyweight. Their results were impressive. They used device called a mandometer to encourage children to eat at a slower rate. This training produced a clinically significant reduction in bodyweight, which was sustained 12 months post treatment.
The prospect that we can manipulate eating behaviour to reduce energy intake is tantalizing because this approach has potential as an effective treatment for obesity. Moreover, an opportunity exists to change our eating behaviour by manipulating the physical characteristics of food. If this can be achieved then we may be able to design foods to encourage behaviours (e.g., slow eating) that reduce our calorie intake from meal to meal. Importantly, for these benefits to be realised, we need to discover the underlying mechanism. This is an important objective of this project.
In the first instance we will develop a method to quantify and characterise 'eating topography' - collectively, the pattern of behaviours associated with eating; swallow rate, bite size, eating rate, and so on. With this tool, we will run a series of experiments to identify specific aspects of eating topography that influence our food intake.
In a second set of experiments we will focus on the mechanism. Two hypotheses will be tested. Firstly, we will explore the prospect that a causal relationship exists between specific aspects of eating topography and the hunger and fullness that we experience at the end of a meal and during the period between meals. There are two reasons why this relationship might exist. Eating topography may change levels of hormones that control our appetite. Alternatively, it may influence the formation of memory for a meal - a process that is known to influence the amount of food that we eat at a subsequent meal.
Our second hypothesis relates to the eating topography that is associated with particular foods. If a food is eaten with a topography that makes us feel full then we may remember this relationship. In future, when we encounter that food again, we may expect the food to be more filling and select a smaller portion. By this account, eating topography influences our energy intake by changing the way we make decisions about portion size, before a meal begins.

There is mounting evidence that eating rate has a marked effect on energy intake in humans. For example, under controlled conditions, eating at a slower rate is found to promote self-reported fullness and to reduce energy intake. Differences in eating rate are meaningful because they predict variability in bodyweight in large-scale population studies. Moreover, significant and sustained (12 months post-treatment) reductions in BMI and body fat have been reported when obese children are trained to moderate their rate of eating using a 'mandometer.'
Given the role that eating rate plays in energy intake it is surprising that little is known about the underlying process. In Phase I we will use EMG and an eating pattern monitor to quantify and characterise 'eating topography.' This will be achieved by taking simultaneous measures of bite size, eating rate, swallow rate, inter-bite interval, and so on. Using this measure, we will identify specific aspects of eating topography that influence energy intake from meal to meal.
In Phase II we will identify the process by which eating topography comes to influence energy intake. Specifically, we will explore two hypotheses. First, we will determine whether a causal relationship exists between eating topography and satiety in the inter-meal interval. In particular, we will measure direct effects of eating topography on appetite-regulating hormones (ghrelin, CCK, PYY, GLP-1, and insulin) and indirect effects on attention and 'memory for recent eating.' Second, we will explore whether the effects of eating topography are learned and expressed in the 'expected satiety' of foods and in decisions about portion size, before a meal begins.

We see three areas where our project could have considerable social and economic impact:

1. FOODS FOR WEIGHT MANAGEMENT
Several sources indicate that eating topography (eating rate in particular) influences energy intake from meal to meal. Indeed, this relationship appears to have an accumulative effect on energy balance because it is a good predictor of BMI in large population studies. For the first time, we will expose the underlying process. In addition, we will identify the key aspects of eating topography (chew rate, inter-bite interval, etc) that influence energy intake.
In collaboration with our industry partner, we will use this understanding to explore ways in which foods might be modified to encourage these specific patterns of eating. If this is successful, then this approach might be applied to enhance the efficacy of commercial products that are designed to confer benefits for weight loss. In relation to this form of impact, Study 8 is important, because it illustrates how the fundamental research in this project might be applied. We also note that this project is submitted under the LINK scheme. During triannual meetings we will reserve half a day to discuss ways in which our results might be exploited and applied to promote weight loss. More generally, both the PI and Co-I have regular contact with researchers in several major food companies. We will use this network to ensure that our findings can be exploited at the earliest opportunity.

2. TREATMENT OF OBESITY
In part, our interest in eating topography stems from the recent discovery that by manipulating eating rate it is possible to achieve a significant and sustained (12 months post treatment) reduction in BMI and body fat in otherwise obese children. As a direct result of this project, we will have a better understanding of how this intervention works. Moreover, with this understanding we will be well-placed to identify ways in which it might be improved, simplified, and implemented more widely and cost effectively.
To achieve this impact we will collaborate with Professor Julian Hamilton-Shield, who was directly involved in the clinical trial establishing the efficacy of the mandometer. We have already agreed to explore ways in which our research findings might be implemented in a clinical setting. As part of this process we will also involve Dr Jeremy Burn, who has considerable expertise in the field of electronic instrumentation. Again, Dr Burn already collaborates with our group. He has agreed to work alongside this project to explore ways in which modifications to eating behaviour might be achieved in a home environment.
Finally, we will explore opportunities to collaborate with Dr Andrew Johnson who treats obese patients at the Avon Obesity Service (Southmead NHS Hospital, Bristol). This collaboration will provide an ideal opportunity to evaluate the clinical significance of our research findings in an adult obese population.

3. PROMOTING BEST PRACTICE IN DIETARY BEHAVIOUR
Our research has considerable potential to inform policy makers and heath professionals. By the end of this project we will be well-positioned to comment on ways in which distraction and specific eating behaviours contribute to overeating. To assist with evidence-based practice, results from our research will be submitted to target journals that are likely to reach a broader audience of health professionals and policy makers (e.g., the American Journal of Clinical Nutrition).
Finally, to realise the broader impact of our results we recognise the benefits of demonstrating that eating behaviour predicts future weight gain. Researchers in the Nutrition and Behaviour Unit are currently conducting prospective studies of this kind using the 'Freshman 15' model. In this context, we intend to include measures of eating behaviour as predictors of weight gain.