It is perhaps worth noting that “slow food” is not simply an antonym for fast food, at least as the term “fast food” is commonly used (i.e., by those who don’t follow the slow food movement).
Here’s a Wikipedia link:
As far as I can tell, (but I am certainly not an expert on this topic), to members of the slow food movement, any mass produced, mass grown, and/or heavily processed food is “fast food”, even if you buy some ingredients from a grocery chain store and prepare a meal yourself. So, for example, if I bought some tomatoes, flour, eggs, herbs, and ground beef from a local grocery store and whipped up some pasta, using hand rolled noodles and a home-made sauce from an old family recipe, this would still be “fast food” because i made it out of ingredients that are all products of large-scale agribusiness. (but maybe the less austere slow foodies would give me partial credit for at least cooking the food the “slow” way).
It seems likely that the slow food founder played off of “fast food” in the traditional sense of food from McDonald’s, etc. (and the generally negative associations with such food, even by those who frequently eat it!) in coining a name for his movement, but somebody who doesn’t like to eat food from a fast food chain is not necessarily a “slow food” adherent.