casomorphins

So would the wise policy in this case be to restrict people's access to milk products?

And sugar, and fat, if this is the milk tea I'm thinking of (aka bubble tea / boba tea)

lots of sugar. A typical large bubble tea contains 11 spoons of sugar. The total recommended sugar consumption in all foods and drinks is 7 spoons.

And plenty of studies have linked excess sugar with depression [1]

[1]: https://www.webmd.com/diet/what-to-know-about-sugar-and-depr....

Yes. Some vendors allow you to control the sugar content, at least. I had ordered a drink with "light" sugar once (1/4 of normal amount) and it still tasted plenty sweet to me, and probably still topped at 350-400 calories. I usually never drink my calories.

It's often a social event too so could be related to the "addiction" of hanging out with friends.