Impact of exercise timing on perceived appetite and food reward in early and late chronotypes: An exploratory study in a male Saudi sample

There is very limited evidence on the influence of diurnal exercise timing on appetite control, and none on food reward or how an individual's chronotype could moderate such effects. We examined the impact of acute exercise timing on perceived appetite and food reward in young Saudi adults with early or late chronotypes. Forty-five young adults (23 ± 4 years; BMI = 25.1 ± 4.0 kg/m2) completed the Morningness–Eveningness Questionnaire (MEQ) and were divided into early (score = 59 ± 5) or late (score = 41 ± 6) chronotypes. Participants attended the laboratory after ≥4 h fast on two occasions for an AM (8:00–10:00) and PM (17:00–19:00) 30-min moderate-intensity cycling bout in a randomized counterbalanced order. Appetite ratings and food reward (Arab Leeds Food Preference Questionnaire) were measured before and after exercise. An acute exercise-induced decrease in hunger was found, which appeared to be dependent upon diurnal timing and chronotype, with hunger being more suppressed after AM exercise in the early chronotypes and after PM exercise in the late chronotypes. There was greater wanting for low-fat sweet foods after AM exercise relative to PM exercise, whereas there was greater wanting for high-fat sweet food and sweet relative to savoury food after PM exercise compared to AM exercise. These preliminary findings suggest that diurnal timing of exercise impacts food preferences, and that chronotype may influence the appetite response to an exercise bout at different times of day.