Restoring counts takes time
Restoring iron values takes a while, just like the onset and development of iron deficiency doesn't happen overnight. It is a question of balance where the uptake of iron needs to match the losses.
Natural losses include for instance loss of blood through menstruation and natural intake is based on the diet.
The regular amount of iron we need in a mixed diet is 12 - 18 mg in total per day.
In healthy individuals the average iron demand is 1 mg daily for men, 1.5 - 2.5 mg daily for women and during pregnancy 2-3 mg daily corresponding to a total of 500 - 1 000 mg, which will be absorbed from the daily diet.
This means that if our intake is lacking this amount or the losses are larger, iron deficiency will eventually develop.
A normal adult carries 3,5 – 4 g iron (3 500 – 4 000 mg), so a turnover of less tha 20 mg per days means a situational change will take time.
This is the natural state and the body is not adopted to having the normal turnover increased many times.
In normal health iron management in the body is conservative with little or no loss of body iron save 1-2 mg being excreted, principally by sloughing of cells from the gastrointestinal tract and skin, and menstruation.