Time-of-Day Effects of Fasted Exercise on Energy Intake

NCT ID: NCT06947824

Last Updated: 2026-02-06

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

NA

Total Enrollment

35 participants

Study Classification

INTERVENTIONAL

Study Start Date

2025-04-01

Study Completion Date

2025-12-15

Brief Summary

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This trial's aim is to investigate the time-of-day effects (morning vs. evening) of fasted exercise on acute and 24h post-exercise energy intake. Specifically, we will compare the effects of fasted morning exercise (12h overnight fast) vs. fasted (6h and 12h) evening exercise on total energy intake during a post-exercise ad libitum test meal as well as on 24h (free-living) energy intake. The secondary aim is to assess subjective appetite ratings before, immediately after, and 30 min post-exercise (visual analog scale). Healthy men and women aged 18-30 years will be included.

Detailed Description

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In a five-way crossover design, participants will complete three fasted and one non-fasted exercise sessions on a treadmill in randomized order on weekdays with one week in between sessions: once in the morning (\~1h after participants' habitual wake-up time) following a 12h overnight fast (12h AMEx), once in the evening (exactly 12h after the 12h AMEx condition) after a 6h fast (6h PMEx), and once in the evening (identical to the 6h PMEx condition) following a 12h fast (12h PMEx). As control conditions, a subsample of participants (n=17) will also complete a fed morning exercise condition (AMEx Fed; identical timing to 12h AMEx) and a fed evening exercise condition (PMEx Fed; identical timing to 12h PMEx), following a small pre-exercise snack (\~10% of individual energy requirements; 30 min before exercise). The standardized meals provided before the fasting period contained 30% of the individual's daily energy requirements and consisted of \~50% carbohydrates, \~30% fat, and \~20% protein.

Conditions

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Health Energy Intake Eating Behaviors Appetite

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

CROSSOVER

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

NONE

Study Groups

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Fasted Morning Exercise (12h AMEx)

Exercise will take place in the morning, following a 12h overnight fast

Group Type EXPERIMENTAL

Fasted Morning Exercise (12h)

Intervention Type BEHAVIORAL

A 30-minute exercise session will take place on a treadmill in the morning (7:00, \~1h after participants' habitual wake-up time), after a 12h overnight fast. The session will consist of 30 minutes of steady state cycling at 65% of VO2max, following a 5 min warm-up.

Fasted Evening Exercise (6h PMEx)

Exercise will take place in the evening, following a 6h period of fasting

Group Type ACTIVE_COMPARATOR

Fasted Evening Exercise (6h)

Intervention Type BEHAVIORAL

A 30-minute exercise session will take place on a treadmill in the evening (19:00, exactly 12 hours after the morning session), after a 6h fasting period. The session will consist of 30 minutes of steady state cycling at 65% of VO2max, following a 5 min warm-up.

Fasted Evening Exercise (12h PMEx)

Exercise will take place in the evening, following a 12h period of fasting

Group Type ACTIVE_COMPARATOR

Fasted Evening Exercise (12h)

Intervention Type BEHAVIORAL

A 30-minute exercise session will take place on a treadmill in the evening (19:00, exactly 12 hours after the morning session), after a 12h fasting period. The session will consist of 30 minutes of steady state cycling at 65% of VO2max, following a 5 min warm-up.

Fed Morning Exercise (AMEx Fed)

Exercise will take place in the morning after consuming a small snack (30 min before exercise)

Group Type ACTIVE_COMPARATOR

Fed Morning Exercise (AMEx Fed)

Intervention Type BEHAVIORAL

A 30-minute exercise session will take place on a treadmill in the morning (7:00, \~1h after participants' habitual wake-up time), after consuming a small pre-exercise snack (30 min before exercise). The session will consist of 30 minutes of steady state cycling at 65% of VO2max, following a 5 min warm-up.

Fed Evening Exercise (PMEx Fed)

Exercise will take place in the evening after consuming a small snack (30 min before exercise)

Group Type ACTIVE_COMPARATOR

Evening Fed Exercise (PMEx Fed)

Intervention Type BEHAVIORAL

A 30-minute exercise session will take place on a treadmill in the evening (19:00, exactly 12 hours after the morning session), after consuming a small pre-exercise snack (30 min before exercise). The session will consist of 30 minutes of steady state cycling at 65% of VO2max, following a 5 min warm-up.

Interventions

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Fasted Morning Exercise (12h)

A 30-minute exercise session will take place on a treadmill in the morning (7:00, \~1h after participants' habitual wake-up time), after a 12h overnight fast. The session will consist of 30 minutes of steady state cycling at 65% of VO2max, following a 5 min warm-up.

Intervention Type BEHAVIORAL

Fasted Evening Exercise (6h)

A 30-minute exercise session will take place on a treadmill in the evening (19:00, exactly 12 hours after the morning session), after a 6h fasting period. The session will consist of 30 minutes of steady state cycling at 65% of VO2max, following a 5 min warm-up.

Intervention Type BEHAVIORAL

Fasted Evening Exercise (12h)

A 30-minute exercise session will take place on a treadmill in the evening (19:00, exactly 12 hours after the morning session), after a 12h fasting period. The session will consist of 30 minutes of steady state cycling at 65% of VO2max, following a 5 min warm-up.

Intervention Type BEHAVIORAL

Fed Morning Exercise (AMEx Fed)

A 30-minute exercise session will take place on a treadmill in the morning (7:00, \~1h after participants' habitual wake-up time), after consuming a small pre-exercise snack (30 min before exercise). The session will consist of 30 minutes of steady state cycling at 65% of VO2max, following a 5 min warm-up.

Intervention Type BEHAVIORAL

Evening Fed Exercise (PMEx Fed)

A 30-minute exercise session will take place on a treadmill in the evening (19:00, exactly 12 hours after the morning session), after consuming a small pre-exercise snack (30 min before exercise). The session will consist of 30 minutes of steady state cycling at 65% of VO2max, following a 5 min warm-up.

Intervention Type BEHAVIORAL

Eligibility Criteria

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Inclusion Criteria

* BMI of 18.5.0-30.0 kg/m2
* weight stability (≤2.5 kg weight change during the past 3 months)
* ability to exercise at a vigorous intensity for 30 minutes

Exclusion Criteria

* pregnancy or breastfeeding
* smoking
* history of or current eating disorders
* medical condition or use of medication that could affect appetite or pose any contraindications to exercise

As the menstrual cycle can cause fluctuations in food cravings and appetite, women of childbearing age were only eligible if they used hormonal contraceptives. To ensure constant exposure to exogenous estrogen and progestin throughout the study phase, participating women were further asked to use active hormone pills throughout the study period in both studies, a practice that is considered both safe and efficacious.

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Minimum Eligible Age

18 Years

Maximum Eligible Age

30 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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Technical University of Munich

OTHER

Sponsor Role lead

Responsible Party

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Karsten Koehler

Prof. Dr. Karsten Köhler

Responsibility Role PRINCIPAL_INVESTIGATOR

Locations

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Technical University of Munich

Munich, Bavaria, Germany

Site Status

Countries

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Germany

Other Identifiers

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MvE_FastEx

Identifier Type: -

Identifier Source: org_study_id

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