Fig. 1: Overview of study design variants for fasted and fed exercise interventions currently used in research.

Participants typically arrived at the laboratory following an overnight fast and undergo one of four interventions (A: FastEx + Meal, B: FastEx + NoMeal, C: FedEx + Meal, D: FedEx + NoMeal), after which an ad libitum meal can be provided. Energy expenditure, subjective hunger and gastrointestinal hormone concentrations via serial blood sampling are often measured at regular interval throughout the laboratory visit. After the meal participants are free to leave the laboratory, and may be asked to keep a record of what they eat for the remainder of the day to calculate 24-h energy intake. Participants would then return to the lab on a separate day and following an adequate washout period to undergo one of the three remaining interventions. Note: participants would normally only complete two exercise interventions: one fasted (FastEx + Meal or FastEx+NoMeal) and one fed (FedEx + Meal or FedEx+NoMeal). ALM, ad libitum meal.