Yellow is a colour people notice quickly. Apparently it's the reason the creators of The Simpsons decided to make the skin colour of most of the characters yellow, so people would pause while channel flipping. I also heard that blue suppresses hunger... which is interesting because the kitchens in Rhodes Farm (a youth anorexia clinic several documentaries have been made about) are coloured blue and brown. As for the argument about addiction, the common response is that "you can quit heroin but you need to eat" That's true, but there's a difference between eating 2 times a day or eating several small snack sized meals across the span of the day, and eating jumbo sized portions as snacks on top of 3 even larger meals within a 24 hour timespan.