phrasal verbs - Grammar Explanation for "be used to"

I'm teaching an intermediate ESL class that focuses on writing. There is a lot of grammar, but it is rudimentary and I am trying not to confuse the students with too many complicated terms. In class today we did a lesson on gerunds and infinitives and one of the sentences that was used in the textbook was:

Which meals are you used to eating in a fast-food restaurant?

Of course the combination of "to" + "eating" confused everyone. I did a quick aside to clarify the situation, but promised to revisit the sentence next class. Now I'm stuck because I realize that I don't entirely understand the grammar myself.

Is "be used to" simply a phrasal verb that takes an object, which in this case is a gerund (eating)? Alternatively, is "used to" a complement that requires an object? How would you explain the situation using minimal jargon?

Any clarification would be appreciated. Thanks in advance.

Answer

The expressions be used to, get used to and become used to are rarely used in other than the complete forms. An exception is :

Used to getting all his own way, Ben threw a tantrum.

However, this can be interpreted as a deleted form of 'As he was ...', and a stodgier alternative is 'Used as he was to getting all his own way, Ben threw a tantrum.'

Though it's not easy to find a reference saying that 'be used to' is best considered as a transitive multi-word verb (in ESL-speak 'a phrasal verb that takes an object'), My English Pages certainly seems to treat it as unitary:

Be used to is used to say that something is normal, not unusual.

Jane Lawson, in an article at Daily Step English, concurs:

So the structure [is]: ... ...

be used to or get used to + noun or gerund (for example: I am used to living in London.)

However, Quirk in ACGEL labels 'used to' in this sense an adjectival, which one could compare to 'familiar with'. There aren't many verbs that would work in front of this adjectival (if one decides to analyse it as such), when you think about it. Be, get, become, seem, feel, grow spring to mind.

I'd say that the construction falls in a grey area where {tMWV + DO} and {link verb + adjectival (with complement)} overlap.

Pointing out that to is the infinitive marker in 'I want to leave' but not in 'I am used to eating ...' may be helpful.