Effect of physical activity calorie equivalent (PACE) labels on energy purchased in cafeterias: a stepped-wedge randomised controlled trial

BackgroundA recent meta-analysis suggested that using physical activity calorie equivalent (PACE) labels results in people selecting and consuming less energy. Only one included study was conducted in a naturalistic setting, in four convenience stores. The current study aimed to estimate the effect of PACE labels on energy purchased in worksite cafeterias. Methods and findingsA stepped-wedge randomised controlled trial to test the effect of PACE labels (which include kcal content and minutes of walking required to expend the energy content of the labelled food) on energy purchased. The setting was ten worksite cafeterias in England, which were randomised to the order in which they introduced PACE labels on selected food and drinks following a baseline period. The study ran for 12 weeks with over 250,000 transactions recorded on electronic tills. The primary outcome was total energy (kcal) purchased from intervention items per day. The secondary outcomes were: energy purchased from non-intervention items per day, total energy purchased per day, and revenue. Regression models showed no evidence of an overall effect on energy purchased from intervention items, -1.3% (95% CI -3.5% to 0.9%) during the intervention. Of the 10 cafeterias, there were null results in five, significant reductions in four, and a significant increase in one. There was also no evidence for an effect on energy purchased from non-intervention items, -0.0% (95% CI -1.8% to 1.8%), and no clear evidence for total items -1.6% (95% CI -3.3% to 0.0%). Revenue increased during the intervention, 1.1% (95% CI 0.4% to 1.9%). Study limitations include using energy purchased and not energy consumed, and access only to transaction-level sales, rather than individual-level data. ConclusionOverall, the evidence was consistent with PACE labels not changing energy purchased in worksite cafeterias. There was considerable variation in effects between cafeterias, suggesting potentially important unmeasured moderators. Trial registrationThe study was prospectively registered on ISRCTN (date: 30.03.21; ISRCTN31315776).