Foods can be classified as relatively more yin or more yang based on their growth, structure, and composition. Carrots, orange, condensed root vegetables that grow below the ground, are yang; expanded ground vegetables, like onion and squash, are more balanced; green leafy vegetables that grow above the ground, like kale, are yin; and fruit, growing high above the ground, is even more yin.
In this way, all food and drink can be classified from yang (∆) to yin (∇). To adapt to our environment, we need to maintain a dynamic balance between yin and yang in our diet. If one eats a diet rich in meat and eggs, which are strong yang foods, one is naturally attracted to foods in the strong yin category, requiring a larger amount of tropical fruit and sugar, for instance, to make balance.
However, maintaining a diet based on such extremes can be challenging and chaotic, which is why more inherently balanced foods from the central category are recommended for regular consumption. Within this category, foods are listed from the most balanced (whole grains, beans, vegetables, and seaweed) that are eaten more frequently and in larger quantities, to less balanced foods, such as nuts and fruit, which are eaten occasionally and in smaller amounts.
(figure from The Book of Macrobiotics, Michio Kushi)