Help formulate a question to the positive sentence with "to have"

Question

What would be a question to a positive sentence:

You have to eat before workout.

If you put it as:

Do I have to eat before workout?

does it mean that to have is not a modal verb in that context?

Answer 1

According to Wikipedia the typical modal verbs are:

can     dynamic modality    She can really sing.
can     epistemic modality  That can indeed help.
could   dynamic modality    He could swim when he was young.
could   epistemic modality  That could happen soon.
may     deontic modality    May I stay?
may     epistemic modality  That may be a problem.
might   epistemic modality  The weather might improve.
must    deontic modality    Sam must go to school.
must    epistemic modality  It must be hot outside.
shall   deontic modality    You shall not pass.
should  deontic modality    You should stop that.
should  epistemic modality  That should be surprising.
will    epistemic modality  She will try to lie.
will    deontic modality    I will meet you later.
would   epistemic modality  Nothing would accomplish that.

and have/have to is not one of them (have + past participle might be, though).

"Have to" expresses a meaning similar to must (and sometimes but not too often shall, should, will, would). modal verbs, but "have to" itself is not a modal verb.

You would never say "Do I must eat before workout" but this perfectly fine with have to.

It can be part of a modal verb phrase, such as "can have + past participle", "may have + past participle", etc. in which case it's modal.