Portion size
This topic covers two areas:
- 'Expected satiety' and meal planning
- New portion reduction strategies
'Expected satiety' and meal planning
The term ‘expected satiety’ refers to the satiety that is expected from a food when it is compared with other foods on a calorie-for-calorie basis. Our unit has pioneered the development of tools and software that quantify these expectations with precision.
We believe that expected satiety is an essential determinant of food choice, meal size, and energy intake. Several large-scale observational studies and surveys show that humans plan the amount of food that they are going to eat in advance of eating. Our work has revealed the important role of expected satiety in this planning process and we have published widely on this topic.
The NBU has accommodated a range of projects relating to expected satiety and we are starting to resolve some fundamental questions. Where do these expectations come from? Why do they differ across foods? How can we increase the expected satiety of a food?
For further information, please visit our Wikipedia page; https://en.wikipedia.org/wiki/Expected_satiety
Links to funded projects:
- Enhancing and consumer expectations of snack foods to promote healthy dietary behaviour
- Understanding decisions about portion size: The key to acceptable foods that reduce energy intake?
- Does flavour-nutrient inconsistency compromise energy regulation in humans?
- Understanding eating topography: The key to reducing energy intake in humans?
- Nudge-it (European Commission-funded FP7 project)
Novel strategies for successful portion reduction
Portion size and food intake:
Portion size plays an important role in determining the amount of food that we consume. However, portion reduction is tricky. If we make food portions smaller then people might simply compensate by eating other foods.
One way to resolve this problem is to reduce portion sizes in combination with other changes that enhance consumer satisfaction.
Achieving sustained decreases in energy (food) intake is key to maintaining healthy weight and combating overweight and obesity. Our Nudge150 project combined two approaches. The first of these arises from the fact that there is not tight physiological control of energy balance. While this underlies our vulnerability to overeating, it also means that it is possible to reduce our food intake without experiencing irresistible hunger. It has been found that if people under-eat at one meal, they do not fully compensate with increased eating at subsequent meals. So, if we ate 150 kcal less at lunch every day for a year, we might expect to eat 18,250 kcal (365 x 50 kcal) less over that year, which would help to prevent weight gain, or might even cause slight weight loss. Our focus on reduced portion size is consistent with the UK Government's 'Responsibility Deal' and public health initiatives in other counties.
See: Nudge150 project – “Combining small changes to foods to achieve a sustained decrease in energy intake” (BBSRC DRINC)
Portion size and food choice:
Another problem with portion reduction is that people might simply choose other ‘competitor’ food products. This is a significant challenge for the food industry. Partnering with Mondelēz, one of our BBSRC-funded Ph.D. students, Roya Shahrokni (supervised by Jeff Brunstrom) has been exploring ways to quantify this choice switch point in consumer behaviour. Building on this, she has been developing ways to ensure that consumers continue to choose their favourite products, even after they have been ‘downsized’.