Socioeconomic position and the influence of food portion size on daily energy intake in adult females: two randomized control trials

Abstract

Background. Large portions of energy-dense foods drive overconsumption and are more readily available in socioeconomically deprived areas. Reducing portion sizes of commercially available foods could be an effective public health strategy to reduce population energy intake, but recent research suggests that the effect portion size has on energy intake may differ based on socioeconomic position (SEP). Objective. We tested whether the effect of reducing food portion sizes on daily energy intake differed based on SEP. Methods. Participants were served either smaller or larger portions of food at lunch and evening meals (N = 50; Study 1) and breakfast, lunch and evening meals (N = 46; Study 2) in the laboratory on two separate days, in repeated-measures designs. The primary outcome was total daily energy intake (kcal). Participant recruitment was stratified by primary indicators of SEP; highest educational qualification (Study 1) and subjective social status (Study 2). Secondary indicators of SEP in both studies included household income, self-reported childhood financial hardship and a measure accounting for total years in education. Results. In both studies, smaller (vs larger) meal portions led to a reduction in daily energy intake (ps < .02). Smaller portions resulted in a reduction of 235kcal per day (95% CI: 134, 336) in Study 1 and 143kcal per day (95% CI: 24, 263) in Study 2. There was no evidence in either study that effects of portion size on energy intake differed by SEP. Results were consistent when examining effects on portion-manipulated meal (as opposed to daily) energy intake. Conclusion. Reducing meal portion sizes could be an effective way to reduce overall daily energy intake and contrary to other suggestions it may be a socioeconomically equitable approach to improving diet. These trials were registered at www.clinicaltrials.gov asNCT05173376andNCT05399836.

Passive overconsumption? Limited evidence of compensation in meal size when consuming foods high in energy density: Two randomised crossover experiments

“…Participants were served a lunchtime meal of beef chilli con carne and oven cooked potato fries, which varied in ED across sessions. This meal was chosen as it is a popular meal in the UK and found to be generally well liked in previous research (Langfield et al, 2023). All food items, and ingredients along with their nutritional information are provided in Table 2.…”

“…Participants were provided with a snack box to eat from after the lunch session. When participants returned for the evening meal, they were served a main course of a cheese and tomato pasta, as used in a previous study (Langfield et al, 2023), a side serving of vegetables, a dessert buffet and 500 g of water (See Supplementary Material III for all additional foods).…”