Effects of changes in portion size on meal eating behaviour in overweight women

Abstract

Exposure to large portion sizes has been linked with positive energy balance and weight gain but the mechanism is unclear. Large portions may influence the amount of food we put in our mouth (bite size), how fast we consume it (eating rate), or how this speed is maintained over the course of the meal (deceleration rate). We present preliminary data on the eating rate (ER), bite size (BS) and deceleration rates (DR) among 21 overweight women. Participants attended the laboratory on two occasions at lunch time after a 3 h fast and consumed a small (229 g; 43% below standard) or large (700 g; 75% above standard) portion of a chilli-con-carne meal in random order. Meal eating parameters were measured with the Sussex Ingestion Pattern Monitor. Mean BS for the small and large portions was 8.3 ± 0.6 g and 11.4 ± 1.7 g (mean difference −3.1 ± 1.4 g, 95%CI −6.2 to −0.1, n13). Mean ER did not differ between portion sizes (small 60.2 ± 5.1 vs. large 58.2 ± 5.0 g/min, n19). Median DR was lower for the large compared with the small portion (0.001 vs. 0.004 g/s2, n13). For the small meal, ER (r = 0.53) and DR (r = 0.51) correlated significantly with BMI (n21) and BS correlated with restraint scores (r = 0.56, n13). Compared with a small portion, exposure to a large portion of a hot meal led to an increase in bite size and a reduction in the deceleration rate towards the end of the meal. These changes may contribute to excessive energy intakes with exposure to large portion sizes.