word usage - "more than pack" or "more than packing"

A sugar study published in the Journal of the American Medical Association, finds sugar does more than just pack on the pounds.

From the dictionary, I know that pack on the pounds means to gain weight, but pack here, I guess, is used as a verb. So should it more appropriate to substitute packing for pack? Just as follows:

A sugar study published in the Journal of the American Medical Association, finds sugar does more than just packing on the pounds.

Answer

The question seems to be about the use of packing or pack*.

It is fine to use the bare infinitive after "to do", as in the following examples:

What does sugar do to you?
It packs one the pounds, doesn't it?
Yes, it does make you fat.

You would not see this written (or hear this spoken) as:

*What does sugar doing to you?
It packs one the pounds, doesn't it?
*Yes, it does making you fat.

So similarly, if it does more than one thing, we still use the same form:

What does sugar do to you?
It does make you fat.
Well, it does more than pack on the pounds.