Large servings make us eat more, even when we are are taught about the impact of portion size on consumption, according to investigators from the University of New South Wales, Australia.

People who learned how to engage in mindful – instead of mindless – eating still ate much more food than those given smaller servings with no orientation regarding mindful eating.

The researchers explained in the Journal of Health Psychology that we need to find new ways to reduce the impact of portion size on overeating.

Author, Dr. Lenny Vartanian, a senior lecturer in the UNSW School of Psychology and an author of the paper, said:

If no effective approaches are found, it may be necessary to develop policy-related changes to provide a healthier food environment for people.”

Most experts believe that portion sizes at home and in restaurants, which have increased considerably over the last 40 years, have contributed to the obesity explosion.

Dr Vartanian said “Studies have consistently shown that increases in portion sizes for a wide range of foods and beverages result in increased energy intake. And the impact is not affected by factors such as hunger or the taste of the food.”

The authors say that their study, which involved 96 women, is the first to examine the effectiveness of educating people about this phenomenon. The women were randomly selected to be served one of two portion sizes of macaroni with tomato sauce for lunch:

  • Large portion – 600 grams
  • Smaller portion – 350 grams

Half the women in either group were placed in a “mindfulness group”, they were given a brochure about how external factors, including portion size, social and cultural influences, advertising, and mood can contribute to overeating. They were then asked to write about how such factors affected their food consumption in the past.

The participants in the mindfulness group were taught how to concentrate on the internal sensations, such as the feelings of hunger and satiety, as well as the taste of food, before being given their pasta meal.

Dr Vartanian said:

“Neither of these brief exercises reduced the effects of portion size. Overall, participants in the larger portion group consumed about a third more pasta – 69 grams – than those in the smaller portion group.”

The participants in the large portion group consumed 87 more calories than the ones in the smaller portion group.

In March 2012, Dutch researchers explained in the journal Flavour that strong aromas lead to smaller bite sizes, and might also help control portion size.

Written by Christian Nordqvist