Satiety, Microbiome, Appetite Regulation, and Tracking Energy Across Targeted Snacks: Chronic Study (SMARTEATS-RCT)

September 9, 2026 updated by: Zoe Global Limited

The ZOE SMART EATS (Satiety, Microbiome, Appetite Regulation, and Tracking Energy Across Targeted Snacks) Chronic Randomised Controlled Trial: Investigating the Chronic Effects of a High-fibre Plant-based Snack Bar on Subjective Daily Hunger, the Gut Microbiome and Gastrointestinal Symptoms in Healthy UK Adults.

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

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

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.

Study Type

Interventional

Enrollment (Estimated)

100

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • 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
  • Living in the UK

Exclusion Criteria:

  • 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
  • Previously purchased any ZOE products (including Daily30, ZOE gut health bar or ZOE app membership).
  • Have taken any medication or product that may modify the measured study outcomes, in the past 3 months (including but not limited to: fibre supplements, antibiotics, non-topical steroids or other immunosuppressive medicines, probiotics or prebiotics, metformin, GLP-1 receptor agonists, lipid-lowering medications such as fibrates, statins, PCSK9 inhibitors, non-steroidal anti-inflammatory drugs)
  • Have used opiate pain medication or a proton pump inhibitor for 8 or more consecutive days during the past 3 months
  • Have experienced a heart attack, stroke or major surgery in the last 2 months
  • Have received treatment for cancer in the last 3 months
  • Are currently pregnant, breastfeeding or planning a pregnancy
  • Are diagnosed with an eating disorder, type 1 diabetes mellitus or type 2 diabetes mellitus

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Intervention
Snack intervention (2x snack bars). To be eaten instead of regular snacks twice a day for 5 weeks.
Other: High-fibre plant-based snack bar
High-fibre plant-based snack bars.
Placebo Comparator: Control
Control snack (2x snack bars). To be eaten instead of regular snacks twice a day for 5 weeks.
Other: Control snack bars
Commercially available snack bars (UK); reflects the energy and macronutrient profile of a typical UK snack.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Daily hunger
Time Frame: 2-hourly intervals for 3 days, at baseline and week 5 of the intervention.
Subjective hunger ratings, assessed using digital visual analogue scales (VAS; 0-100), with anchor points 0 = 'not at all hungry', 100 = 'extremely hungry'.
2-hourly intervals for 3 days, at baseline and week 5 of the intervention.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Microbiome composition
Time Frame: Baseline, week 5 of the intervention.
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.
Baseline, week 5 of the intervention.
Weight
Time Frame: Baseline, week 5 of the intervention.
Self-reported body weight (kg).
Baseline, week 5 of the intervention.
Body mass index (BMI)
Time Frame: Baseline, week 5 of the intervention.
BMI (kg/m2) calculated from self-reported body weight (kg) and height (cm).
Baseline, week 5 of the intervention.
Waist & Hip circumference
Time Frame: Baseline, week 5 of the intervention.
Self-reported waist and hip circumference (cm).
Baseline, week 5 of the intervention.
Gastrointestinal symptoms
Time Frame: Baseline, week 5 of the intervention.
Subjective gastrointestinal symptoms, assessed using the Gastrointestinal Symptoms Ratings Scale. Participants rate symptoms on a 7-point scale ranging from 'no discomfort' to 'severe discomfort'.
Baseline, week 5 of the intervention.
Stool frequency
Time Frame: Baseline, week 5 of the intervention.
Self-reported stool frequency (bowel movements per week) assessed via online questionnaire.
Baseline, week 5 of the intervention.
Stool consistency
Time Frame: Baseline, week 5 of the intervention.
Self-reported stool consistency assessed via the Bristol Stool Form Scale. Participants rate their average stool consistency on a 7-point scale.
Baseline, week 5 of the intervention.
Satiety
Time Frame: Baseline (3-days), week 5 of the intervention (3-days)
Subjective satiety ratings, assessed using digital visual analogue scales (VAS; 0-100), with anchor points 0 = 'not at all', 100 = 'extremely'.
Baseline (3-days), week 5 of the intervention (3-days)
Subjective energy, mood & alertness
Time Frame: Baseline (3-days), week 5 of the intervention (3-days)
Subjective ratings of energy, mood and alertness, assessed using digital visual analogue scales (VAS; 0-100), with anchor points 0 = 'not at all', 100 = 'extremely'.
Baseline (3-days), week 5 of the intervention (3-days)
Sleep
Time Frame: Baseline, week 5 of the intervention.
Self-reported sleep quality, assessed using the Pittsburgh Sleep Quality Index. Scores range from 0-6, with higher scores indicating poor sleep quality.
Baseline, week 5 of the intervention.
Energy and nutrient intake
Time Frame: Baseline (3-days), week 5 of the intervention (3-days).
Energy (kcal) and nutrient intake (g/day; %EI), assessed using digital food log (myFood24).
Baseline (3-days), week 5 of the intervention (3-days).

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Treatment acceptability
Time Frame: Week 5 of the intervention.
Acceptability of intervention and control treatments, assessed via online questionnaire at endpoint.
Week 5 of the intervention.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Zoe Global Limited

Investigators

  • Principal Investigator: Berry E Sarah, Professor, King's College London

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 14, 2026

Primary Completion (Estimated)

November 21, 2026

Study Completion (Estimated)

December 1, 2026

Study Registration Dates

First Submitted

August 13, 2026

First Submitted That Met QC Criteria

August 19, 2026

First Posted (Actual)

August 24, 2026

Study Record Updates

Last Update Posted (Actual)

September 14, 2026

Last Update Submitted That Met QC Criteria

September 9, 2026

Last Verified

September 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • ZOE SMART EATS - Chronic

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

To protect participant privacy, individual participant clinical data and any data that could be used to identify individuals will not be publicly available and cannot be deposited in public repositories. In line with journal requirements, data underlying the results in the publication may be made available to bona fide researchers for reproducibility of results. Proposals, researchers or institutions requesting data will be approved if they meet the standard criteria related to ethics, privacy and data protection regulations.

IPD Sharing Time Frame

Starting 6 months after publication.

IPD Sharing Access Criteria

The study data can be released to bona fide researchers by submitting a research proposal approved by a subpanel of our scientific advisory board which meets once per month with independent members to assess proposals. The data may be pseudo-anonymised or otherwise redacted to comply with the UK General Data Protection Regulation (GDPR). Researchers will be required to enter into a GDPR data sharing agreement before data may be released. Access request proposals should be sent to data.papers@joinzoe.com.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • ANALYTIC_CODE

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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