low iron/hemoglobin

I did some general bio-chem exams by giving blood today.
My iron and hemoglobin levels are VERY low. My hemoglobin is at 33 and my coach’s reaction was this: :eek: She’s having me go easy till Sunday and eat right cause apparently I’m not eating well and I need more iron-rich foods. Then she wants me to do the test again on Monday. I think this is stupid. Can the hemoglobin level possibly rise in such short period even if I start eating right and increasing my iron intake? And what does rest have to do with my hemoglobin levels?