The question assumes the heel pad thins with age. The wording of the source is narrower than the question, so it is worth reading closely.
What the term means
Cleveland Clinic defines heel fat pad syndrome as the thinning of the fat pad that supports and cushions your heel. Age enters the picture in the same source, in a sentence about what can and cannot be changed.
What the source says about age
Cleveland Clinic writes: "Although wear and tear from increasing age or a family history of this condition can’t be prevented, you can focus on certain lifestyle habits to lower your chance of developing heel fat pad syndrome."
That wording ties age to wear and tear and stops there. Be wary of any answer that supplies a detailed biological story without naming where it comes from.
What to confirm, and with whom
Heel pain in Itasca or anywhere else can have more than one name attached to it. Ask a podiatrist whether the pad is the problem or whether the pain belongs under another heading. These pages carry other headings to compare against: the AAFP evidence-based review of plantar fasciitis, the MedlinePlus overview of heel injuries and disorders, and the Cleveland Clinic page on heel bursitis.
The clause readers skip
Read the two verbs in the quoted sentence. Age and family history "can’t be prevented." Lifestyle habits only "lower your chance." Neither verb promises that the pad will stay thick.