Satiety, Microbiome, Appetite Regulation, and Tracking Energy Across Targeted Snacks: Acute Postprandial Study

Overview

The goal of this clinical trial is to learn how eating different snack foods affects acute hunger, energy intake and eating behaviour in healthy adults. The study will be conducted remotely over 5 days. The main questions it aims to answer are: 1. Does eating a snack bar intervention change how hungry participants feel later in the same day? 2. Does eating a snack bar intervention change participants' energy intake, nutrient intake and eating behaviour on the same day? 3. Does eating a snack bar intervention change participants mood, energy levels and alertness later in the same day? Researchers will compare an intervention snack bar to a control snack bar to see if the intervention improves hunger, energy intake, eating behaviour, and other subjective measures. Participants will: * Eat 2 snack bars for breakfast on 2 separate days, with 2 days in between * Not eat anything after 9pm the night before each test day * Fill out short online surveys (under 5 minutes) before breakfast and at set times over the next 3 hours * Not eat for 3 hours after breakfast * Write down everything they eat that day

Diet, and snacking behaviour in particular, plays an important role in long-term health. Snacking now contributes substantially to daily energy intake in the UK and US: data from the ZOE PREDICT study show that 95% of adults snack at least once a day, with snacks accounting for around a quarter of daily energy intake (2.28 snacks/day). However, the average UK snack has a poor nutrient profile, high in refined carbohydrates, added sugars, and saturated fat, and low in fibre and micronutrients, a pattern linked to poorer cardiometabolic health. Despite public health guidance to consume at least 30g of fibre a day, UK adults consume an average of around 20g/day. However, the composition and timing of a snack are important determinants of its effects on hunger, energy, and other health markers. This trial evaluates an intervention (2 x snack bars) against a control (2 x snack bars that reflect the average nutrient profile of snacks currently sold in the UK). Using a control snack bar means any effects observed can be attributed to the specific formulation of the intervention snack bar, rather than simply to a change in snacking habits or a reduction in overall snack consumption. The primary aim of the study is to determine whether the intervention snack bars reduce subjective postprandial hunger (in the hours after eating them), compared with control snack bars broadly representative of the average UK snack nutrient profile. The study will be conducted in 2 phases. In this phase (phase 1; acute postprandial study), 54 participants will complete a crossover postprandial study measuring hunger, satiety, mood, energy, and alertness over 3 hours, and as an end of day measure following consumption of the intervention or control; as well as eating behaviour and subsequent energy and nutrient intake on that day. The postprandial design allows the acute, within-day effects of the intervention snack bars to be assessed under tightly controlled conditions.