Whats the name of the actress playing the one who

leads the Super Slimmer sessions? I think she's awfully good - I can't ell who she is because they say her name too seldom in the episodes for me to check her out in the credits.

She has a wonderful blinkered icy superiority that suits the role perfectly. E.g., the priceless reaction on her face when told that that the people in the Super Slimmers magazine were not all Super Slimmers themselves, but models and actresses - "But that's impossible!"