Medication can screw with a site's calculations. It can't possibly take account of that.
Have you had your doctor confirm this is a result of that medication? Those numbers do seem awfully low.
You can manually set your own range with a minimum of 1200 calories. If you require 1,000 and your doctor approves of that low an intake, you will need to ignore the goals and use a post-it note or something. The system will not let anyone set a goal that low.
Deb, in New Zealand