Glycaemic Responses to a Food Intake Sequence Intervention in Free-living Elite Female Athletes

NCT07247513 | Completed

• 2 other identifiers: FOODSEQ-GRFA2022.12954.BD
• Study Type: interventional
• Target: 22
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical trial is to investigate the impact of a food intake sequence intervention under free-living conditions on glycaemic responses in elite female athletes. Specifically, the main questions it aims to answer are:

• On day 1, athletes will eat freely. An educational session on the study protocol and food sequence manipulation will be delivered, and informed consent, questionnaires, screening assessments, and CGM fitting will be completed. Data collected by the CGM during the first 24 hours will be disregarded due to sensor stabilisation. Hence, this period will serve for familiarisation only.
• On days 2 and 3, one group will eat the last meal of the day (i.e., supper) in a CHO-last meal pattern, while the other will follow a CHO-first meal pattern; on days 3 and 4 one group will eat breakfast in a CHO-last meal pattern while the other will follow a CHO-first meal pattern.
• On days 4 and 5 (supper) and 5 and 6 (breakfast), participants in each group will adhere to the alternate condition. Concurrent data on potential confounding factors (e.g., dietary intake, physical activity, internal and external load during training sessions/competition, sleep quantity and quality, menstrual cycle phase/status) will be collected. Due to the short camp duration, implementing a one-day washout period will not be feasible. Therefore, repeated measurements over two consecutive days per condition will be obtained to minimise carryover effects of the food intake sequence from prior meals on end-of-intervention data (the final 24 hours per condition), and to assess intraindividual consistency of outcomes at matched-times and standardised settings. Glycaemic responses will be compared within-participant between food intake sequences using linear mixed models with random intercepts, to account for repeated measures, interindividual variability, and potential missing data.

Conditions

Healthy; Nutrition; Glycemic Variability; Dietary Intervention; Sleep; Exercise

Keywords

food order; meal sequence; glycaemia; sport nutrition

Outcome Measures

Primary Outcomes (1)

• Incremental interstitial glucose peak after a standardised test meal

  Difference between CHO-last and CHO-first meal patterns in the incremental interstitial glucose peak (mmol/L) adjusted for baseline, following standardised breakfasts (independent of and coinciding with subsequent exercise) and the end-of-intervention (days 3 and 5) standardised supper, assessed using a blinded continuous glucose monitoring system (Freestyle Libre Pro IQ).

  0-120 minutes following a standardised test meal

Secondary Outcomes (11)

• Incremental area under the interstitial glucose curve after a standardised test meal

  0-120 minutes following a standardised test meal

• Time-to-peak interstitial glucose after a standardised test meal

  0-120 minutes following a standardised test meal

• Time out of interstitial glucose range after a standardised test meal

  0-180 minutes following a standardised test meal

• Interstitial glucose dip after a standardised test meal

  0-180 minutes following a standardised test meal

• Interstitial glucose concentrations during specific activities

  24 hours

Study Arms (2)

CL - CF

EXPERIMENTAL

The interventions (carbohydrate-last meal pattern (CL) or carbohydrate-first meal pattern (CF)) will be delivered in random order. If participants are allocated to this study arm, they will receive the CL on the first 2 days and the CF on the next 2 days of the study period.

Other: Carbohydrate-last meal pattern; Other: Carbohydrate-first meal pattern

CF - CL

ACTIVE COMPARATOR

The interventions (carbohydrate-last meal pattern (CL) or carbohydrate-first meal pattern (CF)) will be delivered in random order. If participants are allocated to this study arm, they will receive the CF on the first 2 days and the CL on the next 2 days of the study period.

Other: Carbohydrate-last meal pattern; Other: Carbohydrate-first meal pattern

Interventions

Carbohydrate-last meal pattern OTHER

Participants will consume the main dietary sources of protein, fat, fibre and/or polyphenols before the main dietary sources of simple carbohydrate in the standardised test-meals (breakfast and supper) and will be encouraged to maintain this food intake sequence in the remaining meals of the day. Participants will be instructed to consume lunch and dinner within 30 min, and breakfast and supper within 15 min at a comfortable pace, without intervals between the carbohydrate and non-carbohydrate-rich meal components.

Also known as: CL, CHO-last

CF - CL; CL - CF

Carbohydrate-first meal pattern OTHER

Participants will consume the main dietary sources of protein, fat, fibre and/or polyphenols after the main dietary sources of simple carbohydrate in the standardised test-meals (breakfast and supper) and will be encouraged to maintain this food intake sequence in the remaining meals of the day. Participants will be instructed to consume lunch and dinner within 30 min, and breakfast and supper within 15 min at a comfortable pace, without intervals between the carbohydrate and non-carbohydrate-rich meal components.

Also known as: CF, CHO-first

CF - CL; CL - CF

Eligibility Criteria

• Age: 18 Years - 64 Years
• Gender Eligibility Details: Cisgender
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Adult (18-64 years old)
• Women
• Elite athletes (meeting training and performance caliber criteria ≥Tier 4; McKay et al., 2022)

You may not qualify if:

• Normal glucose tolerant according to the latest review standards of the American Diabetes Association (ElSayed et al., 2024): HbA1c \<5.7%, fasting plasma glucose \<5.6 mmol/L (100 mg/dL), or 2-h plasma glucose \<7.8 mmol/L (140 mg/dL) during a 75-g OGTT
• Able and willing to provide informed consent and safely comply with study procedures
• Any medical condition or behaviour deemed either to pose undue personal risk to the participant or introduce bias into the experiment (e.g. pregnancy, alcohol or substance abuse; any condition affecting the glucose and lipid metabolism or appetite, reviewed on a case by case basis)
• Any reported medication or supplementation that may interfere with the glucose metabolism (e.g., acarbose, aspirin, berberine, insulin, metformin, semaglutide, sulfonylureas, thiazide diuretics, thiazolidinediones, vitamin C). Other medication and supplementation will be reviewed on a case by case basis.
• Recent change in body mass (± 2 kg in the last 2 months)
• Smoking

Sponsors & Collaborators

• Universidade do Porto: lead
• Federação Portuguesa de Futebol: collaborator
• Fundação para a Ciência e a Tecnologia: collaborator

Study Sites (1)

Cidade do Futebol

Oeiras, Lisbon District, 1495-433, Portugal

Location

MeSH Terms

Conditions

Motor Activity

Condition Hierarchy (Ancestors)

Behavior

Study Officials

• Rita Giro

  Faculty of Nutrition and Food Sciences of the University of Porto (FCNAUP); FPF Academy, Federação Portuguesa de Futebol

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Masking Details: It is not possible to blind participants or researchers envolved in data collection to the intervention assigned in each period due to the nature of the intervention and comparator (food intake sequence of the same elements within a meal). However, both will be blinded to CGM data throughout the study.
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: This trial is designed as a randomised, counterbalanced, crossover, open label, superiority trial with two groups. Block randomization will be performed by an external researcher with a 1:1 allocation ratio, and allocation concealment will be ensured through the use of sequentially numbered, opaque, sealed envelopes.

Study Record Dates

• First Submitted: November 14, 2025
• First Posted: November 25, 2025
• Study Start: November 24, 2025
• Primary Completion: November 29, 2025
• Study Completion: November 29, 2025
• Last Updated: December 5, 2025

Record last verified: 2025-12

Data Sharing

• IPD Sharing: Will share
• Shared Documents: SAP, ICF
• Time Frame: IPD will become accessible following the publication of all study findings.
• Access Criteria: IPD will be made available to researchers with legitimate scientific purposes (such as systematic reviews or meta-analyses).

Locations

PT (1)