Well did his pants not fit him properly before?

That is definitely one hole you won't be able to dig yourself out of, OP.

That's one way of cheating the system. I wish that I would have thought of that. In all seriousness though, it's usually not wise to bring up weight at all, unless, you have a very close relationship with someone.

Maybe you did a good thing asking that

Should have complimented his pants after, was a risky question from the start

Don't comment on peoples' weight unless you ask them to - there's way too many ways to upset people. Even if he had lost weight, it could have been due to anything from depression and stress to cancer or an eating disorder.

In other words, don't ask people anything

You can bring up other topics at Thanksgiving besides controversial politics and you can compliment people on qualities besides their amount of body fat. Avoiding riskier topics sometimes isn't a total blanket.

Very confused, someone explain please?

His boss purchased pants larger than normal, OP noticed and assumed his boss had lost weight. Which he didn't.

how was that confusing? it was pretty straight forward...

19, I was confused as to how she didn't notice he was wearing larger pants.

probably didn't notice the size difference on the tag. Unless they only sell pants by color coded sizes in Canada...

25, I can confirm that we do not.

Just say..well my compliment still stands. Nice trousers.

So what? You were just trying to be nice is all

Same effect with zero effort. Next time, compliment him on his cunning.

Well, that's another solution to the problem.