"That's the beauty of argument. When you argue correctly, you're never wrong."
The Japanese diet. Rice and fish, to be frank. Not many westerners know that Japan only recently adopted the idea of eating meat on a regular basis. And by recent I mean within the last 100-150 years, around the same time as the westernization of Japan began: when Commodore Matthew Perry forced the Japanese to open their borders for foreign commerce in 1854. This essentially began the eventual "wedging" of American and western culture into the Japanese world. Obviously the diet was just one small consequence.
But how healthy is it in Japan? Honestly, it depends on you. The Japanese cuisine is better for your system most of the time, but every style of food has its temptations, and Japanese is no different. Cakes, chocolates, pies, cookies... It's just a matter of self control. Definitely one of the most unique foods I've encountered in Japan is their version of fruit. Japan imports regular fruit to be distributed in supermarkets just as they would be in the western world, but they also refine and concentrate different fruits, to be sold at a much higher price. Think of it as super-fruit. Watermelon is probably the most expensive example of this - maybe ¥30,000 to buy a large square watermelon.
If you want to spend all your time devouring Oreos and McDonald's that is your decision. But, you should be a little concerned about your fat intake in Japan - not because you gain weight, but rather because you lose it. I don't see too much concentrated protein or fat in the Japanese diet, and as a result, I've lost more weight than I care to lose. Not because I was fat before, but because I haven't built up enough muscle to compensate for the lost fat.
If you maintain a relatively healthy lifestyle in Japan - running, biking, walking, martial arts - you can probably expect the same to happen to you. It's extremely difficult to build up muscle mass when there is no protein to build upon. I'm 6'0" and I only weight 76 kg. Believe me, that's too light. My arms have lost their fat reserves and my legs look a bit smaller as well. On the other hand if you enjoy being thin, lean, and a little lanky, Japan just might be the country for you. Bring some steak with you just in case; I've also heard there's an Outback Steakhouse in Osaka.
So what does this mean for you? Just be careful. If you eat nothing but rice, fish, and soup the whole time you're in Japan, you will look very Japanese-ish. Think of your strength as like the endurance of a cheetah - you might be the fastest animal on the planet, but you can't keep it up too long.
I won't say Japan has gone too westernized in terms of its food - many people, especially in Tokyo, dine on fast food just because they are the ones who need to eat on the run. But usually you can expect the native food to take precedent for lunch and dinner - a bento for lunch, and a homemade or izakaya dinner. Breakfast is another story - the Japanese breakfast includes rice, fish, and miso. In terms of Japanese food, this offers the least variety I've ever seen. They don't even offer light western alternatives. The cereal in Japan is quite simply Frosted Flakes, Coco Krispies, Corn Flakes... and these seem to be catered to children, unlike in the US, which offers them to all ages. Don't expect too many varieties of cereal or cold breakfast foods. Many, many Japanese people are seeing the advantages in bacon and eggs, toast, pancakes, etc. Unhealthy? Yes. Filling? Definitely.
Learn about what foods will be necessary to maintain a similar diet before you arrive in our borders. Trust me, it's difficult if you're reinventing your food routine, and it's one less thing to worry about once you get here. What should you expect? Pasta, rice, fish, meat (but light), and no turkey. I have a feeling once I go back and inhale Austin's Mexican food, I will throw up from happiness... yeah, and the food being way too heavy.
News as of late - the author of SurvivedSars is in Japan, making use of his Chinese skills to read Kanji. Traveling to Onomichi on Monday to see the Senko Temple. The Shinkansen is insanely fast, even after knowing how fast it is. Good yakiniku (Japanese BBQ) - Gyukaku restaurant. I'm also attempting to travel home for Xmas, so will need to contact the proper authorities in Japan. Keeping up with running, blogging, studying Japanese, and encouraging the discussion of funny cultural differences... I live to tell another day.