I'm more interested in principles of eating based on a practical understanding of the process by which food becomes blood which is capable of re-animating every part of our bodies.
A healthy person, by definition in Chinese Medicine, will choose foods which keep them healthy. A healthy person will have an appetite perfectly appropriate for what they need. A healthy person's appetite will fluctuate depending on weather conditions and how much exercise, rest and sleep they get.
People doing a lot of mental exercise will need rest. However, most people these days work themselves at jobs which expend mental energy and they don't allow for spontaneous naps. In this situation a healthy person's appetite will step in and tell them to go get some sugar. This is especially true as the afternoon wears on (but it can happen at anytime of day or night).
Sugar is what the blood needs to keep transporting qi to the front lines, or oxygen to the cells if you prefer. The effect of eating sugar is instantaneous, but it also wears off quickly, leading to another craving. Eating sugar for a boost occasionally is not a problem. However, doing this for years on end leads to degeneration of the internal organs. A long list of diseases could follow here, from just being a whiny neurotic spaz, to advanced-stage-limb-amputating diabetes.
Often times people with this late afternoon craving for sugar will try to suppress it. While I have no doubt that there are people with extraordinary discipline making this work, most people will crack under the pressure. Cracking leads to binging.
Many people know they don't have the discipline so they turn to appetite suppressants like tobacco, coffee or tea. Each of these has potential negative side affects, however, depending on where you work, they can be good for your social life, which is one of the strongest statistical indicators for longevity. Of course, because I'm into Chinese medicine, I have to say that if we are comparing appetite suppressants, green tea has the least negative side effects . But I've seen plenty of people abusing green tea.
Chocolate and Diet Coke (or other caffeinated sodas) are a sort of self back-stabbing compromise between sugar and suppressing the appetite. The average "health" bar, with 52 suspicious ingredients you need a PhD in Chemistry to digest, is just as bad.
Rice Balls to the Rescue!
What if, when that late afternoon weariness starts to set in, instead of getting sugar or caffeine, instead you eat a rice ball? Rice is a complex carbohydrate. In order for rice to become sugar in your blood steam, your digestive organs have to do some work. Because they are doing work, they won't get lazy, and when they don't get lazy, they don't degenerate, and when they don't degenerate they don't lead to all those nasty diseases.
The boosting effects of eating a rice ball are not as instantaneous as drinking a Coke but the energizing effects will last much longer. Also rice balls have seaweed on the outside and usually something stimulating inside like umeboshi (sour plum), a pickle, or a small piece of delicious fish.
Rice balls are really really good snacks.
If you live in Japan, you can get them everywhere at 7-Eleven corner stores. You probably know that once the nori (seaweed) has been applied to the rice, it will start to get soggy. After about 6 hours it becomes chewy instead of crisp. But 7-Eleven solved that problem with the worlds most brilliant and longevity inspiring technology. They wrap the rice ball in plastic then put the seaweed on, then another piece of plastic. And they have those anti-moisture-oxygen absorbing packets in there too. If you pull the three tabs in the correct 1,2, 3 order (see picture), the seaweed wraps around the rice ball as you pull off the wrapper!!! They are fantastically fresh and tasty! Why don't all 7-Elevens carry rice balls? It isn't fair! Write your Congressman today, tell them how you feel, tell them that Rice Balls are the answer to America's problems.
(In the interest of full disclosure, while writing this post I drank some pu-erh tea, ate a pickle and had a small piece of chocolate. Now I'm going to take a nap!)