Keep in mind that 30% of your fat calories will not be absorbed. My experience is that the calorie recommendations are very accurate because they're based on individual parameters like age, sex, current weight, goal weight etc. As weight is lost, the system will automatically lower calorie and fat guidelines. Starting too low doesn't leave any room for change.
alli works best with an adequate amount of calories AND fat. It's not a program where less is better. There are two great posts on why calories and fat are (each) so important at the top of this message board. It's terrific information, and I think you'll find it helpful.
Please let me know if you need anything else.
Pat Baird, MA, RD, registered dietitian