1. There are other differences in Japan -- most obviously a very different diet
2. Obesity rates in other countries are catching up to the United States.
3. The first two points call into question your claim that Americans are uniquely lacking in willpower.
4. I don't want to live in a society where people are fired or ostracized for being fat because it is cruel and inhumane.
5. The US has a $66 billion weight loss market, suggesting many Americans do want to lose weight (cf., https://www.prnewswire.com/news-releases/us-weight-loss-mark...), but I'll leave it to the oracles to decipher what you mean by "really" want.
1. There are other differences in Japan -- most obviously a very different diet
2. Obesity rates in other countries are catching up to the United States.
3. The first two points call into question your claim that Americans are uniquely lacking in willpower.
4. I don't want to live in a society where people are fired or ostracized for being fat because it is cruel and inhumane.
5. The US has a $66 billion weight loss market, suggesting many Americans do want to lose weight (cf., https://www.prnewswire.com/news-releases/us-weight-loss-mark...), but I'll leave it to the oracles to decipher what you mean by "really" want.