Abstract
Background: The aim of this research was to investigate whether increased portion sizes of vegetables and
decreased portion sizes of meat on main dishes increased the amount of vegetables consumed in a real-life
restaurant setting without affecting customer satisfaction. The participants were unaware of the experiment.
Methods: A cross-over design was used in which three restaurants were randomly assigned to a sequence of an
intervention and control condition. In the intervention period, the vegetable portion sizes on the plates of main
dishes were doubled (150 g of vegetables instead of 75 g) and the portion sizes of meat on the plates were
reduced by an average of 12.5%. In the control period, the portion sizes of the main dishes were maintained as
usual. In total, 1006 observations and questionnaires were included.
Results: Vegetable consumption from plates was significantly higher during the intervention period (M = 115.5 g)
than during the control period (M = 61.7 g). Similarly, total vegetable consumption (including side dishes) was
significantly higher during the intervention period (M = 178.0 g) than during the control period (M = 137.0 g).
Conversely, meat consumption was significantly lower during the intervention period (M = 183.1 g) than during the
control period (M = 211.1 g). Satisfaction with the restaurant visit did not differ between the intervention period
(M = 1.27) and control period (M = 1.35). Satisfaction with the main dish was significantly lower during the
intervention period (M = 1.25) than during the control period (M = 1.38), although in both cases, the scores
indicated that participants remained (very) satisfied with their main dish.
Conclusions: This study showed that increasing vegetable portions in combination with decreasing meat portions
(unknowingly to the consumer) increased the amount of vegetables consumed and decreased the amount of meat
consumed. Furthermore, despite the changes in portion sizes, participants remained satisfied with their restaurant
visit and main dish. The findings of this study suggest that modifying portion size in restaurants
decreased portion sizes of meat on main dishes increased the amount of vegetables consumed in a real-life
restaurant setting without affecting customer satisfaction. The participants were unaware of the experiment.
Methods: A cross-over design was used in which three restaurants were randomly assigned to a sequence of an
intervention and control condition. In the intervention period, the vegetable portion sizes on the plates of main
dishes were doubled (150 g of vegetables instead of 75 g) and the portion sizes of meat on the plates were
reduced by an average of 12.5%. In the control period, the portion sizes of the main dishes were maintained as
usual. In total, 1006 observations and questionnaires were included.
Results: Vegetable consumption from plates was significantly higher during the intervention period (M = 115.5 g)
than during the control period (M = 61.7 g). Similarly, total vegetable consumption (including side dishes) was
significantly higher during the intervention period (M = 178.0 g) than during the control period (M = 137.0 g).
Conversely, meat consumption was significantly lower during the intervention period (M = 183.1 g) than during the
control period (M = 211.1 g). Satisfaction with the restaurant visit did not differ between the intervention period
(M = 1.27) and control period (M = 1.35). Satisfaction with the main dish was significantly lower during the
intervention period (M = 1.25) than during the control period (M = 1.38), although in both cases, the scores
indicated that participants remained (very) satisfied with their main dish.
Conclusions: This study showed that increasing vegetable portions in combination with decreasing meat portions
(unknowingly to the consumer) increased the amount of vegetables consumed and decreased the amount of meat
consumed. Furthermore, despite the changes in portion sizes, participants remained satisfied with their restaurant
visit and main dish. The findings of this study suggest that modifying portion size in restaurants
| Original language | English |
|---|---|
| Article number | 41 |
| Number of pages | 11 |
| Journal | International Journal of Behavioral Nutrition and Physical Activity |
| Volume | 14 |
| Issue number | 41 |
| DOIs | |
| Publication status | Published - 20 Apr 2017 |
Funding
The research reported is funded by the public-private partnership “Meer groente & fruit voor iedereen” (More vegetables and fruit for everyone), sponsored by the Dutch Ministry of Economic Affairs and the Fresh Produce Centre.
| Funders | Funder number |
|---|---|
| Fresh Produce Centre | |
| Ministerie van Economische Zaken |
