The meaning of "food is also sex" is: eating and drinking, this is the nature, that is to say, the love of beautiful things, it is the nature. Food, here is the name of the action, meaning love; color, here for the attitude, the meaning of good.

Source: From "Mengzi - Zhuzi", which records a discussion on human morality between Mengzi and his student Zhuzi (a student of Mozi), who said, "Food and color are also nature. Benevolence, internal, not external; righteousness, external, not internal."

Translation: suzi said, "Eating and drinking, men and women, this is nature. Benevolence is what is within not what is without, and righteousness is what is without not what is within."

Expanded:

A masterpiece of Mencius' in-depth discussion of man's view of life and death, based on his theory of the goodness of nature. Beginning with how people should deal with their own desires, he argues in depth, positively and negatively, that righteousness is more important than life, and that one must give up one's life for righteousness, in terms of life and death, profit and righteousness, and keeping one's righteousness and losing one's righteousness. It also emphasizes that if a person cannot resist the temptation of ten thousand bells, palaces, wives and concubines, and favors, he is bound to "lose his heart (the heart of righteousness)".

Meng Zi, who lived at a time when several great powers were striving to achieve unification through violent means, inherited Confucius' idea of "benevolence" and developed it into the idea of "benevolent government," and was called "The Sage of Asia.

Baidu Encyclopedia - Mencius - Suzi