someone should measure the difference between:
a. eating the icecream during 30minutes b. eating in 5 minutes + working out lightly (take a walk) the other 25
I am by no means against working out, but forcing this dichotomy may dissuade people from taking a simple an useful step that could even be aggregated: Stretch out your previously brief ice cream consumption while doing your normal schedule AND go for that walk. BAM! You're an even bigger winner.
A half hour to eat one serving of ice cream? Madness...