Slow down! exploring opportunites for reducing eating rate

The obesity epidemic demonstrates that people are having difficulties with limiting energy intake to match energy expenditure. Therefore strategies to make controlling energy intake easier and more enjoyable need to be identified. Research suggests that lowering eating rate, i.e. the amount of food consumed per unit of time (g/min), could be an effective strategy. Lowering eating rate is expected to facilitate the control of long-term energy intake and body weight by increasing satiety.

Eating rate can be targeted by means of different approaches. It, however, is still unclear what would be an effective approach for lowering long-term eating rate, and whether it would be successful at lowering long-term energy intake and body weight. Hence, the current thesis investigated several opportunities for lowering eating rate and explored their potential to lower energy intake and body weight. Different approaches were considered:

1. Targeting the person: i.e. to change habitual eating rate (Chapter 2 and 3)

2. Targeting the food: i.e. to select foods that take more time to consume (Chapter 4 and 5)

3. Targeting the eating environment: i.e. to make changes to the direct eating environment of a person (Chapter 6)

In Chapter 2 it was investigated whether eating rate is a stable personal characteristic that is associated with energy intake and BMI using data from the NQplus-cohort. The results confirm that eating rate is highly dependent on the individual and is relatively constant within an individual. Moreover, the analyses show that being a fast eater is associated with a higher long-term energy intake and BMI in the Dutch population.

In Chapter 3 the acceptability of the ‘eating detection sensor’ (i.e. a new electronic device that can potentially be used to retrain a person’s eating rate) was investigated by means of 4 evaluation studies. The results show that people are open to the idea of using such devices for monitoring and retraining eating behavior. These devices, however, need to be comfortable to wear and discreet.

In Chapter 4 the eating rate of the most commonly consumed foods (i.e. how fast they can be consumed, g/min) was investigated. Moreover, it was investigated what the energy intake rate (i.e. the eating rate of a food multiplied by the energy density of a food, kcal/min) of these foods is. Energy intake rate is expected to be a stronger predictor of energy intake than eating rate or energy density as such. The eating rate of 240 foods—representing the whole Dutch diet—was measured in a laboratory setting. The results showed a wide variation in eating rate (range: 2-641 g/min) and energy intake rate (range: 0-422 kcal/min), both within and between food groups. This demonstrates that the foods consumed provide opportunities for selecting alternatives with a lower eating rate and energy intake rate.

In Chapter 5 it was investigated to what extent Dutch adults are consuming foods with a low and high energy intake rate (kcal/min), and whether this is associated with their energy intake and BMI. The dataset described in Chapter 4 was merged with 24h-recall data from the Dutch National Food Consumption Survey to enable these analyses. The results show that the consumption pattern of Dutch adults provide opportunities for lowering energy intake rate. The energy intake rate of the diet was found to be positively associated with long-term energy intake, but not with BMI.

Finally, Chapter 6 describes an experiment that tested whether a person’s bite frequency (i.e. number of bites per minute), and therefore eating rate, is affected by the bite frequency of an eating companion, and whether this has an effect on food intake. It was found that a person’s bite frequency is unaffected by the bite frequency of an eating companion.

Summarizing, the research described in this thesis provides new insights into the opportunities for lowering long-term eating rate, and thereby long-term energy intake and body weight. The results show that lowering a person’s eating rate may result in a lower long-term energy intake and BMI, and that technological solutions could be used to lower a person’s eating rate. Furthermore, the results demonstrate that Dutch adults have ample possibilities to shift their diets towards foods with a lower eating rate, and that it could be a promising strategy for lowering long-term energy intake. We found no evidence that eating rate can be lowered through changes in the direct eating environment.

To conclude, the results of this thesis provide input for the development of randomized controlled trials. These are needed to confirm whether there is a causal relation between eating rate, long-term energy intake and weight status. It is important that the potential of eating rate is further investigated, as lowering eating rate is expected to make people feel full on fewer calories and thereby make controlling energy intake easier and more enjoyable.