If subjects are eligible and decide to participate, they will take part in two identical study trials. One is scheduled before and the other is scheduled after 1 week of overeating controlled by the study team. Subjects who exercise regularly will be instructed to exercise the day before their first study trial - and they will be required to exercise during 6 of the 7 days of the overeating period (including the day before their second study trial). Subjects who do not regularly exercise (no planned physical activity) will remain inactive until the completion of both study trials.