P. Sze 
I love my green tea and I can drink this beautiful & aromatic drink all day long. But it’s not the same variety one would find at typical coffee shop in teabags. I choose to brew green tea leaves from Japan, with the right amount of leaves and the right temperature of hot water, and steep for an appropriate time.
Monday is my “detox” day, so no caffeine, which I like because it helps “reset” my body after a weekend of eating out and drinking wines. In fact, I feel good and don’t even crave any caffeinated drink during the day. But by the late evening, I start fantasizing myself sipping warm green tea in front of my laptop, and just hope that the night flies fast to the next morning in a blink so I can drink the tea again! Yes, I’m obsessed.
But there is one problem. When I drink green tea, I start to feel cold. This is great in summer as helps me get though the hot and humid days of New York City without air conditioning. But in winter, this is not a favorable condition. I can feel my body temperature going down, and feel like I need to wear gloves, extra socks, haramaki and scarves even inside the house. Then I remember that green tea is too yin for winter weather!
We’ve all seen the studies that show that green tea is very healthy, with catechins, flavonoids and other benefits. Some studies show that green tea helps lower the risk of heart diseases, diabetes and even some cancers, so it’s often recommended to drink as an alternative to coffee. But from Eastern philosophy grounded in principles of Yin Yang, the health benefits of green tea is dependent upon many factors.
According to yin-yang philosophy, green tea is very yin. The nature of yin energy is “relaxing”, “loosening” and also, “cooling”. However, when in excess, it can make you feel cold, tired, or even weak, which makes you more susceptible to infections in cold winter. When this happens, I naturally crave the opposite energy, something warm and “strengthening”, or “yang” energy. I would eat pressure cooked brown rice, warm and strong miso soup with root veggies, and some long-cooked bean dishes all day long during the winter, just to make a balance between yin and yang. I also “crave” some quick & vigorous exercise at the gym, which also gives me some warmth, and strength (“yang” energy). Usually with these self regulating choices, I would feel less cold and feel better. And now, I’m in “neutral”, yin-yang balanced state.
However, everybody is different, and you may react to green tea in a different way. I’m mostly vegetarian, 
decided not to eat animal foods more than 10 years ago. So I could call myself more “Yin” type. Therefore, “strong yin” drink such as green tea makes me feel cold and weak very easily. But if you are eating more animal foods (strong “yang” food) , green tea would be very helpful to make a yin-yang balance by “cooling down” your inner heat generated by animal food. So this is why green tea is sometimes beneficial from a holistic point of view. There is no “one fits for all” in Eastern medicine.
Understanding Yin Yang Energy in foods
When you learn to identify certain food and drink as yin and yang, it can help you to choose the most suitable foods to support your unique constitution and current condition. According to Taoist philosophy, good health is a state where opposing energies of yin & yang are balanced in the body. When your yin-yang energies are balanced, you would feel good not just physically, but mentally, emotionally and even spiritually.
We already know how to make this yin-yang balance by eating certain foods instinctively. For instance, when the weather is cold, we naturally crave some nice and warm comfort food such as soup or stew. While on a hot & humid day, chilled drink or tomato salad would be our natural choice, (or ice cream?)
So in the same manner, if you are feeling “Yin”, (cold, tired, weak, low energy etc), you may want to eat more yang foods to feel warm and strong for a balance. Or if your regular diet is centered around animal foods with strong, salty seasonings (a.k.a. modern diet), eating more strong yin foods such as green juice, raw foods, fruits/juice, or even a glass of wine may help balance you out (at least temporarily).
But the same regimens may not be suitable for vegetarians like myself because that would cause “excess yin” conditions, like “I’m feeling cold!”
How you prepare foods also has Yin-Yang energies. Quick cooking methods such as steaming, quick saute, stir fry, salad, are more yin side, while long cooking such as stew, baking or pressure cooking give you more yang energy. So you can also choose more suitable way of cooking depends on the season, your conditions etc.
Foods with “Extreme Yin and Yang” energies
Sugar, alcohol, caffeine, and chemicals are on the extreme Yin end of spectrum, which have a strong effect on our body. Salt, eggs, cheese, meat are on the opposite end, categorized as “Extreme Yang Foods”. When you eat these “extreme” foods, our body naturally tries to make a balance by eating the opposite foods, which is also called “cravings”. I guess I’m not the only one who has to have salty snack when drinking a glass of cabernet sauvignon.
Though it looks like you are making a balance here, your instinct may be telling you that this is not a healthy kind of balance, and overtime, this way of eating could lead to some serious consequences.
So the best strategy is to eat the foods toward the center as your core daily diet, namely whole grains and vegetables (local and seasonal) and other plant based whole foods, as much as you can, instead of see-sawing between “strong or extreme yin or yang foods” such as meat and sugar.
Cause of illnesses — One energy in excess
Eastern medicines teach that the cause of illnesses is imbalance inside your body. When one energy is in excess, you will be out of balance and can develop some health problems. The longer you live on a diet centered around extreme foods (a.k.a. modern diet), the more difficult and the longer it takes to restore your health and equilibrium.
Therefore, the general approach for healing in Eastern medicines or Macrobiotics is to adjust the imbalance of yin and yang by applying the foods in opposite energy first. Then, direct toward the foods in the center, which includes whole grains, vegetables and other plant based whole foods.
Source: http://vibrantwellnessjournal.com/2014/05/26/yin-yang-foods/
