You need a calorie deficit of approximately half a standard daily intake to lose a third of a pound a day.
Over the course of 90 days, you'd lose a grand total of a pound of fat or so.
And then there's this (http://www.medicinenet.com/script/main/art.asp?articlekey=99...)
Despite the fact that all of the subjects spent the same amount of time in exactly the same confined space, the results showed large differences in the number of calories they burned. Some subjects burned as few as 1,300 calories in 24 hours, while others burned as much as 3,600 calories, a difference of 2,300 calories in one 24-hour period!
Keep in mind that most of what these subjects were doing would not be counted as "exercise".
If you want to know more about what I'm talking about with drastic changes in calorie expenditure, do a google search on "non-exercise activity thermogenesis".