3 Fat Chicks on a Diet Weight Loss Community

I originally posted this under the sticky topic about working out and gaining weight but figured it would get overlooked. So I am reposting. Help!

I followed a link posted earlier ( the internetfitness.com/calculators/bmr.htm one) and this is what I got with my inputs:

1517 BMR
3095Total energy requirement (with my current 60min per day of treadmill)
2993 Total energy requirement (if I stop the treadmill)

Those numbers do not make sense to me! I would think that 1 hr of fast walking on a treadmill (3.5 mph 5% incline)would burn more than 100 calories, wouldn't it? And don't the numbers seem very high to begin with? I am 5'3 and around 175 (gotta get a scale) so it seems like my BMR would be lower?? And those numbers with just normal daily activity and with structured exercise seem ridiculously high!

Plus, Medifast, which I am starting tomorrow because the package arrives today, is around 1000 calorie per day right?

I need help figuring this out. I want to lose weight and I wouldn't mind losing 4-5lbs per week as is possible with Medifast, just for the first month though, but I want to lose sensibly and sustainably.

My day is only moderately active without the treadmill ( 2 kids and 1 dog still at home so I keep up with them plus housework) and I have read I am supposed to cut down the treadmill by half the first few weeks. I worry about that. I also worry that I will cut too many calories and end up sabotaging myself.

Any advice?