Carbs or protein before exercise: does sex change how your body burns fuel?
NCT ID NCT07829237
First seen Sep 18, 2026 · Last updated Sep 18, 2026
Summary
Researchers at the University of Toronto are studying whether what you eat before endurance exercise changes how your body uses fuel, and whether that differs between men and women. Twenty-four recreationally active adults will each complete three cycling sessions after drinking either a carbohydrate beverage, a protein-based beverage, or a calorie-free drink. The team will measure how much carbohydrate and fat participants burn during 90 minutes of moderate cycling, and how long they can pedal before exhaustion.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- Pre-exercise carbohydrate or protein beverage
- What this could lead to
- If the trial shows differences, it could help active people choose what to eat or drink before endurance exercise based on their sex.
- What could go wrong
- This is a small, short-term study in healthy, fit adults. The results may not apply to other groups, and any performance differences may be minor.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Not a phased trial
Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.
- Participants
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About 24 people
The number the study aims to enrol. It can still change while the study runs.
- Expected to start
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Sep 2026
An estimate. Start dates often move.
- Expected to finish
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Jun 2027
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 to 35 years
- Sex
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Anyone
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * Participating in ≥150 minutes of moderate-to-vigorous physical activity per week * VO₂peak classified as "good" or above based on American College of Sports Medicine normative values: \>35.0 mL/kg/min for females and \>39.0 mL/kg/min for males * Body mass index (BMI) between 18 and 27 kg/m² * Participating in 3-5 structured exercise sessions per week * Weight stable, defined as within ±2 kg for at least 6 months * Non-smoker * Females must be eumenorrheic Exclusion Criteria: * Polycystic ovarian syndrome (PCOS) or endometriosis Current use of oral contraceptives or oral contraceptive use within the previous 3 months Diagnosed cardiovascular or metabolic disease Hypergonadism or hypogonadism Use of medications for management of blood glucose or lipid metabolism Pregnant or \<12 months postpartum Lactating or breastfeeding within 3 months of study commencement Menopausal Recreational tobacco smoking Inability to complete the study exercise protocols or comply with pre-trial dietary or physical activity controls Use of medications that may affect substrate metabolism, including corticosteroids or non-steroidal anti-inflammatory drugs (NSAIDs) Currently following a low-carbohydrate diet, such as a ketogenic or Atkins diet
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The places running it
1 site. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
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Goldring Centre for High Performance Sport
RECRUITINGToronto, Ontario, M5S 2C9, Canada
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