Large portions of food may contribute to excess energy intake and greater obesity.
| Subjects consumed 30% more energy when offered the largest portion.|
|American Journal of Clinical Nutrition|
However, data on the effects of portion size on food intake in adults are limited.
In this study, researchers from the Pennsylvania State University, USA, examined the effect of portion size on intake during a single meal.
The research team also investigated if response to portion size depended on whether the subject or the experimenter determined the amount of food on the plate.
They served lunch to 51 men and women 1 day per week for 4 weeks.
The meal included an entrée of macaroni and cheese, consumed ad libitum.
At each meal, the team presented subjects with 1 of 4 portions of the entrée. Portions weighed either 500 g, 625 g, 750 g, or 1000 g.
The researchers allocated 1 group their portion on a plate, while the subjects in the second group were able to serve themselves.
The team found that portion size significantly influenced energy intake at lunch.
Subjects consumed 30% more energy (676 kJ) when offered the largest portion than when offered the smallest portion.
In addition, response to the variations in portion size was not influenced by who determined the amount of food on the plate, or by subject characteristics such as sex, body mass index, or scores for dietary restraint or disinhibition.
Dr Rolls’s team concluded, “Larger portions led to greater energy intake regardless of serving method and subject characteristics”.
“Portion size is a modifiable determinant of energy intake that should be addressed in connection with the prevention and treatment of obesity”.