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
Willing and able to follow the study protocol
Willing and able to provide informed consent
Regular consumption of snacks (≥2 per day)
Fibre intake <20 g/d
Have BMI of less than 18.5 kg/m² or more than 40 kg/m²
Have an allergy or intolerance to ingredients in the intervention or control snack bars (including inulin) or cannot eat the food products safely and comfortably for any reason
Have a personal medical history of inflammatory bowel disease, coeliac disease, Crohn's disease, irritable bowel syndrome, chronic constipation, or chronic diarrhoea
Have started a new supplement in the past month, or are unwilling to maintain current supplement use throughout the study
Parallel
High-fibre plant-based snack bar
Other interventionHigh-fibre plant-based snack bars.
Control snack bars
Other interventionCommercially available snack bars (UK); reflects the energy and macronutrient profile of a typical UK snack.
Daily hunger
Subjective hunger ratings, assessed using digital visual analogue scales (VAS; 0-100), with anchor points 0 = 'not at all hungry', 100 = 'extremely hungry'.
Microbiome composition
Relative abundance of selected microbiome species (those included in the ZOE microbiome-health ranks 2025 \& ZOE microbiome-diet ranks 2025), derived from metagenomic analysis of stool samples.
Weight
Self-reported body weight (kg).
Body mass index (BMI)
BMI (kg/m2) calculated from self-reported body weight (kg) and height (cm).
Waist & Hip circumference
Self-reported waist and hip circumference (cm).
Treatment acceptability
Acceptability of intervention and control treatments, assessed via online questionnaire at endpoint.
Microbiome composition
Relative abundance of selected microbiome species (those included in the ZOE microbiome-health ranks 2025 \& ZOE microbiome-diet ranks 2025), derived from metagenomic analysis of stool samples. Measured in a sub-group of participants (approx. n = 20) to determine whether there are detectable changes in the gut microbiome following a short term (2-3 weeks) dietary intervention.
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