First of all, i just want to say different people have different
bodies, at different stages of fitness & different requirement.
Saying from my own experiences, i was once a obese 90kg @
1.70m
At that stage, i would say for me, it is almost impossible to do
interval run or sprint, let alone completing a 2.4km jog without
walking. Even climbing stairs already makes you breathless. People
who are in this stage is not suitable for any intensive exercise
and should condition your bodies first like slow jogging. For me i
condition my body about 1 to 2 months, 4-5 times of slow jog per
week until i was able to complete 2.4km easily without walking. My
weight drop to about 85kg and was stagnant for the 3rd month.
It was then i begin to control what i was eating. Standard things
like no fried food, no skins, no soft or sweet drinks, no junk
food. The amount of food is the same but minus those mentioned
meaning u eat more veg, fruits, water to fill up ur stomach. All
these so call control plus the continue jogging, i managed to drop
my weight to 80 (roughly abt 1mth 1kg) and remain stagnant
again.
As the jogging is beginning to stress my knees, i reduce to twice a
week and i change to 2 sessions of gym overall workout plus weekend
go swim. After 6 months, my wt is 72 now. My target is 68 4 more to
go 
Hope my experience can help ...
