Body weight gain (% to week 0): (A) body weight gain in the L6 condition; (B) body weight gain in the L18 condition; (C) percentage of body weight gain during the last week and the moment before euthanasia in the experiment. Values are expressed as the mean ± S.D. (A,B) or as the mean ± S.E.M. (C); n = 5–6 for the L6 and L18 conditions. The statistical analyses for the figures in (A,B) were performed using 2- and 3-way repeated measures ANOVAs, and for the figure in (C) using 2- and 3-way ANOVAs. The letters t, D, T, and P refer to time, diet (STD vs. CAF), treatment (VH vs. GSPE), and photoperiod (L6 vs. L18) effect, respectively. An LSD post hoc test was used to compare between groups: $ (0.1 < p < 0.05), + (p < 0.05), and +++ (p < 0.001) indicate differences by diet effect; ** (p < 0.01) indicate differences by treatment effect. ns, indicates no significance; STD, indicates standard diet-fed rats; CAF, indicates cafeteria diet-fed rats; VH, indicates rats administered vehicle; GSPE, indicates rats were administered with grape seed proanthocyanidin extract at 25 mg/kg b.w.; L6, indicates short photoperiod with 6 h light per day; L18, indicates long photoperiod with 18 h light per day.