Hello paul,
I had a similar experience a few years ago when we had dietary analysis/feedback from a rather well-built Michael Van Straten (LBC's Doctor Garlic) while on a management course. Many of us when we first saw Michael felt as you did: how can someone with that shape teach us anything about good diet? However, the course tutor emphasized several times that Michael had been challenged by food and this had led to him becoming very knowledgeful.
So, I guess, it depends what you do with your weaknesses as to whether you're hypocritical. My former centre-in-charge always used to say that you were better off teaching subjects you were less good at - you find yourself learning a lot more (hopefully) .
Very best wishes,