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

Technical University of Munich

Status: Enrolling

Conditions: Energy Intake; Health; Eating Behaviors; Appetite

Treatments: Behavioral: Fasted Evening Exercise (6h); Behavioral: Fasted Morning Exercise (12h); Behavioral: Fasted Evening Exercise (12h)

Study type: Interventional

Funder types: Other

Identifiers

NCT06947824

MvE_FastEx

Details and patient eligibility

About

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.

Full 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.

Enrollment: 25 estimated patients

Sex: All

Ages: 18 to 30 years old

Volunteers: Accepts Healthy Volunteers

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.

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: None (Open label)

---

25 participants in 3 patient groups

Fasted Morning Exercise (12h AMEx)

Experimental group

Description:

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

Treatment:

Behavioral: Fasted Morning Exercise (12h)

Fasted Evening Exercise (6h PMEx)

Active Comparator group

Description:

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

Treatment:

Behavioral: Fasted Evening Exercise (6h)

Fasted Evening Exercise (12h PMEx)

Active Comparator group

Description:

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

Treatment:

Behavioral: Fasted Evening Exercise (12h)