Red and yellow do make people hungry, according to research results. People eat more when they are surrounded by warm colors, such as yellow, orange and red. Cold colors, such as blue, purple and black, suppress the appetite.
Because of the association between hunger and warm colors, red, yellow and orange are used in the logos of many fast food establishments. Restaurants also use red on their menus and surround diners with red tablecloths and napkins to help stimulate their appetites. Eateries may also place yellow flowers on the table to increase feelings of optimism as optimistic people are more likely to splurge on their meals.