So-called "starvation mode" may not exist.
The 1200 floor is not about energy needs, and there may or may not be a need for any individual to 're-eat' to get back up to the 1200.
The reason for 1200 is that on anything lower than that, you're probably not getting enough vitamins and minerals.
Once you've had your vitamin C, you don't need to eat more vitamin C if you exercise. :)
However, I would suggest that an intake just on 1200 is probably too low, especially if you're exercising. Remember that Spark gives you a range for a reason, so if you aim for 1200-1550 and somewhere in the middle, you won't even need to ponder this question.
Deb, in New Zealand