...at least according to this study
Exercise duration and intensity in a weight-loss program"When participants were divided by their reported average weekly duration of exercise at months 6 and 12, the group which averaged > or =200 min/week at both time points lost more weight than the groups which averaged <150 min/week of physical activity or whose activity duration was inconsistent (difference among groups, P = 0.01). They also had a greater percent increase in cardiorespiratory fitness than those who averaged <150 min/week of physical activity (P = 0.007) and those whose activity was inconsistent (P = 0.003)."
Chambliss, HO, Clin J Sport Med. 2005 Mar;15(2):113-5