I have no idea about the calorie side of things but I would change the workout to a something a bit harder. I'd do the 5 mins jog at 4mph and then straight onto full speed for as long as you can go. When you're knackered jog lightly at 4mph for a minute before you burst at full speed again. If you can do this for 20 mins then you're in pretty good shape already.
M8 that is pretty much what I do - ill give you a break down.
First 3mins at 4kmph
4th min to 5th min - 5kmph
5th min to 8th min - 8kmph
8th min to 11th min - 10-11kmph (fastest I can go at present)
11th min to 14th min - 8kmph
14th min to 17th min - 10-11kmph
17th min to 20th min - 8kmph
20th min to 23th min -11-12kmph
23th min to 26th min - 8kmph
26th min to 30thmin - 4kmph -3kmph