The Effect of Eating Rate of Ultra-Processed Foods on Dietary Intake, Eating Behaviour, Body Composition and Metabolic Responses-Rationale, Design and Outcomes of the Restructure Randomised Controlled Trial.

Extensive epidemiological research and the findings from one randomised controlled feeding trial (RCT) have shown associations between the consumption of ultra-processed foods (UPFs) and higher energy intakes. To date the specific properties of UPF foods and diets that may be responsible for driving higher energy intakes remain unclear. A comparison of the diets in the single RCT to date showed a significantly higher eating rate (g/min, ER) for meals in the UPF diet compared to those in the minimally processed diet. Numerous acute feeding trials have shown that foods with textures that promote a slower ER tend to be consumed in smaller portions compared to those consumed at a faster ER. Here, we describe the rationale and approach for the Restructure RCT with the primary aim to determine the effect of meal texture-derived ER (g/min) of UPF diets ('UPF Slow ER' vs. 'UPF Fast ER') on daily ad libitum energy intake (kcal/day) across a 14-day period. The secondary objectives of the Restructure RCT are to compare changes in body composition and metabolic markers following the same two diets. We hypothesise that texture-derived differences in ER will moderate food and energy intakes from UPF diets such that participants will consume less when they encounter textures that promote a slower eating rate. The outcomes of the Restructure RCT aim to provide new insights on the proposed mechanisms by which UPF are thought to promote greater energy intakes, and aid in the development of food-based strategies to moderate dietary energy intakes from processed foods. Trial Registration: clinicaltrials.gov identifier: NCT06113146.