This would be an incredible feature. Scenarios below:
I have a dinner party on Saturday and want to bank up an extra 500+ calories by saving 100 a day Mon-Fri.
On Tuesday I work out alot but not hungry, yet ravenous on Wednesday and want to eat my Tuesday calorie leftovers.
On Thursday end of day I overeat and go to bed. Ability to work it off over the weekend so it balances by Monday. Aka atonement.