Learn English – Usage of commas with “albeit”

Nope! There is no call for commas there. "Still" is acting as an adjective in this case, letting the reader know that those opportunities persist. Don't worry that "countless" is also an adjective modifying "opportunities". They are not coordinate adjectives, and so do not require separation.

Your other comma placement (before the second item in a two-item list) is also ill-advised.

I had to read the sentence four times to make sense of it. It is far too convoluted—and quite needlessly so.

Albeit is a conjunction, and as such, it should not be separated from the element (i.e., the word or the clause) that it sets off. It can be used either to start a finite clause (with a verb), or a non-finite clause (including single words)—most commonly the latter. It cannot, however, be placed in the middle of a finite clause that it introduces, just like other conjunctions can’t: it must be placed at the beginning of that clause.

In your example here, the clause initiated by albeit is “whose figures where lower than the aforementioned two groups”. First off, whose has to go, because conjunctions like albeit cannot head a relative clause (which is what a relative pronoun like whose heads); it must be substituted by the appropriate personal or demonstrative pronoun, in this case their: “albeit (that) their figures were lower than the aforementioned two groups”.

You can have albeit initiate this entire clause, but it is quite heavy and clumsy to read; you would be better off by doing what is very commonly done when using albeit with a copular clause like this one: delete the subject (which is already there in the main clause, anyway) and the copula, and keep only the predicate. That way, albeit initiates a non-finite clause, consisting in this case of an adjective plus a preposition and its object: “albeit lower than the aforementioned two groups”.

That would leave you with a much more acceptable sentence:

Obesity rates among men, albeit lower than the aforementioned two groups, increased gradually to approximately 15% of the male population.

I would probably leave out “of the male population” at the end, though: it’s quite obvious that the 15% refers only to the male population, since we’re talking about obesity rates in men. And as @JohnLawler said in his comment, aforementioned is much too bombastic—just use previous or other instead:

Obesity rates among men, albeit lower than the previous/other two groups, gradually increased to approximately 15%.