Men have been warned not to describe women as "Rubenesque" when trying to reassure them about their weight.
Alan Walters, whose girlfriend put on several kilograms after comfort eating provoked by his clumsy remarks about her looks, said: "I hoped I was being supportive and flirty when I compared her to work by the Flemish Baroque artist. But she burst into tears and put it on Facebook, where her friends all told her to dump me."
Walters then spent hours trawling the internet trying to find examples of hot women painted by Rubens.
"Imagine my dismay when I found he he had a thing for obese women with thighs that look like they could crush a man, and rather small breasts."
Dr Philip McKenna, curator at the Courtauld Gallery of fine art, advised men to masturbate while examining works by Rubens before complimenting their partners in his name.
"Standards of beauty have changed a great deal over the past 400 years," Dr McKenna said. "If you can't manage a semi while looking at The Three Graces, don't go there."
"On the other hand, the three girls in his Education of Marie de Medici (1622-1625) are properly fit."