I agree with your comments wholeheartedly that rapid or dangerous weight loss for the simple purpose of visual satisfaction and not 'appearing' fat regardless of health risks is no good.
But I admire the Japanese aesthetic towards delicate and slim features as it applies to women, that is afterall what makes them so physically desireable to men with an interest in Japanese women. The Japanese attitude of moderation and a traditionally healthy diet and active lifestyle with lots of biking and walking has helped maintain this. Practically speaking (beyond all cultural appreciation and discussions of beautiful/not beautiful), it has contributed to longer life spans, increased quality of life, etc. But the over-refined and processed foods of today's Western diet which are creeping into Japanese culture are creating an imbalance and causing obesity and disease to increase.
So to combat this I think the best thing would be if they actually launched a campaign designed to celebrate all of this traditional Japanese aesthetic and way of life rather than introduce quick fix solutions. I think if anyone was suited to implement a simple yet comprehensive daily diet and wellness routine it'd be the Japanese. Their cell phone plans for example are so incredibly complex, by comparison the same system here would confuse the heck out of people. It's like we don't think over here anymore, we can't remember as much and don't try to understand as much as we should. We're being dumbed down, simplified, etc. On construction sites everyone takes 10 mins in the morning to warm up, group exercise, make the effort, etc., and they understand why its important and therefore everyone participates. Work-related injuries are lower therefore and there's less downtime and cost for the company. Over here people are out of shape but don't care. They're throwing out their backs, taking pills up the ying yang and don't really care to change their habits or try to approach the situation wholistically and improve their way of life.
In Japan, I think on the whole, the small things you have to do daily basis to promote health naturally over time would go over well and people would be able to actually remember to do these things and use their will power. Japan doesn't strike me as the kind of lazy place where quick easy fixes are really needed, I think most ousiders agree the Japanese have a pretty serious work ethic and resolve, the people just need the right information but clearly they aren't getting it.