The impact of post-prandial delay periods on ad libitum consumption of a laboratory breakfast meal

This study examined the impact of varying the holding time following an ad libitum laboratory breakfast on acute dietary behaviour and subsequent intake. 24 participants (20 females (age: 23.4±6.3 y; BMI: 23.9±3.9 kg·m-2, mean±SD)) completed three trials following a quasi-randomized, crossover design. Each trial (seven day separation) incorporated a defined post-prandial delay (DPD) period of either zero (no delay), one or three hours following a buffet breakfast consumed over 30-minutes. Dietary intake outcomes included energy, macronutrient and core food group intakes. On completion of the DPD period, participants left the laboratory and recorded all food/beverages consumed for the remainder of the day. One-way repeated-measures ANOVA assessed all outcomes, with post hoc analysis conducted on significant main effects. Energy and carbohydrate intakes were significantly lower on no delay vs one hour (p = 0.014) and three hour (p = 0.06) DPD trials (EI: 1853±814 kJ vs. 2250±1345 kJ vs. 1948±1289 kJ; CHO: 68±34 g vs. 77±44 vs. 69±43 g; respectively). DPD periods did not influence the time to consume next meal or energy, macronutrient and core food group intakes for the remainder of the day. Delaying participants from leaving a laboratory alters dietary intake at an ad libitum test meal. The post-meal holding period is an important methodological consideration when planning laboratory studies to assess appetite. Novelty Bullets: 1. Delaying participants from leaving a laboratory alters dietary intake at ad libitum breakfast meals. 2. The length of the delay period did not affect dietary intake at ad libitum breakfast meals.