Three years ago I read "Wij zijn licht" (we are light) by Gerda Blees. In that book, a group of people decide that they don't need to eat, light is enough. So it was with some amazement that I read the words that Kang gives to the main character, "I can do without food. All that I need is sunlight".  Given the publication dates and that Blees' book is based on a true story, they cannot have influenced each other, which makes it all the more remarkable.
The Vegetarian is a also a remarkable book in other respects. In particular, the story is told from three different viewpoints, but never from the point of view of the main character. That is extraordinarily effective, both making a point in itself and making the reader wonder about what was going on inside their head. 
The opening section, where the attitude of the husband to the protagonist (indifference bordering on contempt) is described, was particularly striking, and actually quite amusing.
It is a short book, which I got though in a couple of days, but so intense that you feel that you have been reading it for longer.