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

Overview

The goal of this clinical trial is to learn how eating different snack foods affects long term hunger and gut health in healthy adults. The study will be conducted remotely over 7 weeks. The main questions it aims to answer are: 1. Does eating a snack bar intervention for 5-weeks change how hungry participants feel throughout the day compared to a control? 2. Does eating a snack bar intervention change gut microbiome, bowel habits, digestive symptoms, and other health measures compared to a control over 5 weeks? Researchers will compare an intervention snack bar to a control snack bar to see if the intervention improves hunger, gut microbiome, digestive symptoms and other health measures. Participants will: * Eat 2 snack bars in place of their usual snacks every day for 4 weeks * Complete health measurements at the start and end of the study: a health questionnaire, 3-day food diary, 3-day hunger \& satiety survey, body measurements, and a stool sample * Fill out a short online survey (under 5 minutes) once a week

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 daily hunger over 5 weeks of daily use, compared with control snack bars representative of the average UK snack nutrient profile. The study will be conducted in 2 phases. In this phase (phase 2; chronic randomised controlled trial), 100 participants (50 per arm) will eat the intervention or control bars daily for 5 weeks. Secondary aims for this phase include the bar's effects on gut microbiome composition, gastrointestinal symptoms, bowel habits (frequency and consistency), subjective mood and energy, sleep quality, and anthropometric measures. The design allows the chronic effects of the intervention snack bars to be assessed when the bars are eaten regularly in place of habitual snack foods.