Knives were used at the table, but most people were expected to bring their own, and only highly favored guests would be given a personal knife. White wine was believed to be cooler than red and the same distinction was applied to red and white vinegar. This was the most common arrangement, even in wealthy households, for most of the Middle Ages, where the kitchen was combined with the dining hall. The cuisines of the cultures of the Mediterranean Basin had since antiquity been based on cereals, particularly various types of wheat. When possible, rich hosts retired with their consorts to private chambers where the meal could be enjoyed in greater exclusivity and privacy. Unlike water or beer, which were considered cold and moist, consumption of wine in moderation especially red wine was, among other things, believed to aid digestion, generate good blood and brighten the mood.
The claims for weight loss are nothing short of outlandish and there is real science that suggests the whole thing is a hoax. Studies that claim to have found weight loss were carried out on animals. Studies involving humans are for the most part badly designed.
A few quality studies have been carried out over the years, starting in 1998 with a double-blind, placebo-controlled trial of 135 adults over 12 weeks published in The Journal of the American Medical Association.