Effects of repeated, alternating 5-day access to chow and 2-day access to either chow (Chow/Chow, n = 16) or highly preferred chocolate-flavored sugary diet (Chow/Preferred, n = 14) in female Wistar rats. Panels show (M ± S.E.M.) (A) (Top) average daily change in body weight, and (Bottom) feed efficiency (body weight change/energy intake) during each C (Chow) or P (Preferred) diet phase of each week, or (B) cumulative body weight gain (Top) and feed efficiency (Bottom). *Differs from Chow/Chow p *< 0.05.