Theres a few variations on this question, but they all generally revolve around the whole hippy/eco-warrior/greenpeace theme. Usually asked by the elderly, who genuinely associate the two things, or by passive-aggressive types, who want to voice their displeasure at you daring to have an alternative lifestyle to them. If the question comes from the former, then explain the difference politely, if from the latter, then enquire to what extent the amount of saturated fat theyre eating is effecting their sexual performance then run - like the cowardly hippy you are.
Lover of all things PC. A fan of inserting indelible ink into the dermis layer of the skin. Remembers when 'geek' was an insult. Still passionately believes Vampire: The Masquerade - Bloodlines was the greatest game ever made.