Clinical trial NCT06947824: Time-of-Day Effects of Fasted Exercise on Energy Intake
Official title: Effects of Fasted Morning vs. Evening Exercise on Post-Exercise Energy Intake
Study type: INTERVENTIONAL
Overall status: RECRUITING
Phase: NA
Conditions: Health
Energy Intake
Eating Behaviors
Appetite
Lead sponsor: Technical University of Munich
Sponsor class: OTHER
First posted: 2025-04-27
Enrollment: 25
Sex: ALL
Minimum age (years): 18
Maximum age (years): 30
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: BASIC_SCIENCE

Brief summary: 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 (0-10 Likert scale). Participants (healthy men and women aged 18-30 years) will complete the 3 study conditions in randomized order.

Detailed description: In a three-way crossover design, participants will complete three 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). The last meal before each fasting period will be standardized, providing 25% (meal occurring 12h before exercise) and 30% (meal occurring 6h before exercise, 6h PMEx only) of individual daily energy requirements.

Eligibility criteria: 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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Primary outcomes:
measure: Acute ad-libitum post-exercise energy intake (test meal)
timeFrame: 30 minutes after exercise
Secondary outcomes:
measure: 24h post-exercise energy intake
timeFrame: 24 hours post-exercise
measure: Subjective appetite measures
timeFrame: before exercise, immediately after exercise, and 30 minutes after exercise
measure: Carbohydrate oxidation
timeFrame: continuously throughout the 30-minute exercise bout
measure: Fat oxidation
timeFrame: continuously throughout the 30-minute exercise bout
measure: Energy expenditure
timeFrame: continuously throughout the 30-minute exercise bout
Other outcomes:
measure: Blood glucose
timeFrame: before exercise and immediately after exercise
measure: Blood lactate
timeFrame: before exercise and immediately after exercise
measure: Breath ketones
timeFrame: before and immediately after exercise
measure: Blood ketones
timeFrame: before exercise and immediately after exercise
Locations:
city: Munich
country: Germany
facility: Technical University of Munich
state: Bayern
Study officials:
References: