360 + 1200 divided by 2 = 780 calories
I'm a big advocate of not overeating or binging on UP days. However, if you messed up your metabolism by eating too little already in the past, I might suggest slightly higher.
Maybe 400 or 500 calories on DOWN days and 1200-1500 on UP days.
In this range, you'd be averaging between 800 and 1000 calories, which still creates a calorie deficit. SparkPeople likely suggests that, in order to lose weight, you might need to eat in a 1200-1550 calorie range, so you'd be staying in this range on UP days, and eating lower on your VLC days.
(I did things differently, but this might work for you.)
Also, you need to choose a plan that you are willing to stick with for a lifetime, not just while you are losing weight, or, you will likely gain the weight back again. It's OK if the weight comes off slowly, as long as it's steady and consistent. I'd be careful, with your history, about going too low.
BUG will likely be along soon to give additional input.
Doing It With Multiple Sclerosis;
2005-2009: 185 lbs. Some minor yo-yo-ing.
2010/Sept: 180 lbs; Waist 46"
2011/Jan 1: 160 lbs; May 22: 133 lbs for DD's wedding
2012/Jan 1: 119.8 lbs; May 1 117.2 lbs
2013/Jan 1 - 121.2 lbs
Monthly wt is in my SP intro
Reached 118 lbs for about 6 months; working hard to maintain weight, w peri-menopuase now;
Goal range: 107-118 lbs/W31.5. Under 123 OK
| current weight: 121.6