Split-plot ANOVA

I am reviewing a manuscript for potential publication for a journal and the authors are examining the percentage change in body fat between 2 groups from baseline (T0), 3 months (T1), 6 months (T2), and 12 months (T3) using a mixed-plot ANOVA. At baseline, their percentage change in body fat is 0 with a standard deviation of 0 because it's baseline only and no change has occurred yet. Should the baseline actually be included in their mixed-plot ANOVA or should they just be using the 3 month, 6 month, and 12 month values?