I have a friend who I would NEVER tell about the diet because I know she would never let it go. I was proved right last weekend when we were at a wedding fair (one of our other friends is getting married) and there was a woman there with a stall advertising a VCDL ketotic diet. She was SO rude to the lady and looked incredulous and said to the woman "Why would ANYONE want a ketotic diet??!!?". I said "they're great, like the Cambridge diet, you can lose weight quite quickly." but she didn't listen. I felt so embarrassed for the lady, it was so rude!
Definitely won't be "'fessing" up to her anytime soon. There's no point even trying to explain. Certain types of people will NEVER understand.