Breaking up prolonged sitting time with walking does not affect appetite or gut hormone concentrations but does induce an energy deficit and suppresses postprandial glycaemia in sedentary adults

Background: Breaking up periods of prolonged sitting can negate harmful metabolic effects but the influence on appetite and gut hormones is not understood and is investigated in this study. Methods: Thirteen sedentary (7 female) participants undertook three, 5 h trials in random order: 1) uninterrupted sitting (SIT), 2) seated with 2 min bouts of light-intensity walking every 20 min (SIT+LA), and 3) seated with 2 min bouts of moderate-intensity walking every 20 min (SIT+MA). A standardised test drink was provided at the start and an ad libitum pasta test meal provided at the end of each trial. Subjective appetite ratings and plasma acylated ghrelin, peptide YY, insulin, and glucose were measured at regular intervals. Area under the curve (AUC) was calculated for each variable. Results: AUC values for appetite and gut hormone concentrations were unaffected in the activity breaks conditions compared to uninterrupted sitting (linear mixed modelling: p>0.05). Glucose AUC was lower in SIT+MA than SIT+LA (p=0.004) and SIT (p=0.055). There was no difference in absolute ad libitum energy intake between conditions (p>0.05), however, relative energy intake was lower in SIT+LA (39%; p=0.011) and SIT+MA (120%; p<0.001) than SIT. Conclusion: Breaking up prolonged sitting does not alter appetite and gut hormone responses to a meal over a 5 h period. Increased energy expenditure from activity breaks could promote an energy deficit that is not compensated for in a subsequent meal.