This clinical trial's primary aim is to investigate the acute effect of two exercise bouts (short [10 minutes] and long [30 minutes]) on appetite and appetite-regulatory hormone responses to a standard meal test. The secondary aim is to investigate when the changes in appetite and appetite-regulatory hormones occur during exercise. As an exploratory aim, the researchers will test if the two exercise bouts influence ad libitum energy intake in the periods after the standard meal test. The researchers will compare three groups (control, short exercise, and prolonged exercise) to see if the exercise bouts affect appetite, appetite-regulatory hormones, and energy intake in healthy men.

Study Design

Screening visit Before conducting the main experiments, the participants will attend a screening visit where consent will be obtained, and they will complete questionnaires to assess health, food preferences, and physical activity. The researchers will then measure the participants' height, weight, waist circumference, and body composition.

After the researchers confirm the eligibility criteria, participants will take part in two treadmill tests to establish maximum oxygen uptake test (V̇O2 max) (Broom et al. 2017).

Experimental design After the screening visit, the participants will complete three main experiments (control, short high-intensity exercise, and prolonged high-intensity exercise) in a counter-balanced design. All experiments began at ~0930, following an overnight fast of at least 10 hours. Participants will consume a prescribed meal in the evening before each main experiment. Following this meal, participants are only allowed to drink water until the start of the main experiments.

At the beginning of the exercise conditions, participants will run on the treadmill for 10 minutes (short) or 30 minutes (prolonged) at a speed estimated to elicit a 75% V̇O2 peak, followed by rest in the laboratory. In the control condition, the researchers will follow the same protocols except that the participants will not perform any exercise. The participants will have a standardized meal after exercise and then an ad libitum buffet meal afterward.

During each experiment, the researchers will assess appetite ratings using 100 mm visual analog scales (Flint et al. 2000). The researchers will also collect blood samples to examine ghrelin, peptide YY, glucagon-like peptide 1, and possibly other blood-borne measures.

Inclusion Criteria:

• Males aged 18 years or older.
• Have stable body mass for at least six months (within ±2 kg).

Exclusion Criteria:

• Females
• People who are younger than 18 or older than 65 years old.
• Have food allergies.
• Have significant contraindications to exercise (e.g., an injury that would inhibit running).
• Smoking.
• Suffering from metabolic health issues, e.g., history of diabetes, cardiovascular disease, or eating disorders.

The stored data will be anonymous and follow the guidelines of the General Data Protection Regulation enforced in May 2018. Hard copies of participant information forms, including consent forms and dietary intake records, will be kept in locked filing cabinets. Keys to the filing cabinets will only be available to the primary investigator. All databases will be password protected and stored on a university computer with firewalls.

Participants' identifiable data will be stored in a locked cabinet. Digital data will be stored anonymously within the server of the University of Glasgow.

This project's Principal Investigator will be responsible for sharing the research data.

Data will be preserved in Enlighten, the official online repository of Glasgow University's research output.

The data will be available when the study is completed.

Data will be preserved for 10 years.

Data will be shared via the repository deposit (Enlighten). Only signatories of end-user agreements can access and use shared data.