So you'd say there are 70,000 calories in 20lbs. She eats 2,870 a day x 497 = 1426390 cal in 497 days. But she needs to eat 70,000 less in that time period so you'd subtract 70,000 from 1426390? = 1356390 divided by 497 = 2729 cal/day? Is that right?