That makes a lot of sense!

There's a similarity to this with a theory on self-confidence: a person who has to boast or show-off to other people is very likely to have low self-confidence. A truly confident person doesn't need to satisfy their ego by boasting because they're content with themselves.

The same applies here, really. Stop telling people you're trying to lose weight and get on with it!

Yep, I can verify this with personal experience. I've done it both ways and it works better if no one knows but me.  My reason was people usually don't have an intelligent response or are feeling inadequate, so they respond with cynicism. And talk you out of it.

@Chris--Another side of the self-confidence coin and feeling the need to tell other people is to get encouragement from the outside, it becomes almost like asking for permission.