County-wide experiment where people pay individualized prices of goods and services based on their height-to-weight ratio. The prices increase as people get farther from their ideal weight.
A way to reduce obesity in society and thereby achieve all of the benefits that stem from it (lower mortality, a lower burden on the medical system, etc).
Country-wide promotion of a healthy lifestyle.
One of the countries that are serious about putting an end to the obesity epidemic could introduce personalized prices of goods and services, based on the person's weight to height ratio. The healthier the ratio, the better the price the person pays.
The weight-to-height price difference would especially affect food, transportation (uber, taxi, public, flights), and anything else where rewarding a healthy lifestyle makes sense.
Somewhere between entering the premises and paying, a person would seemlessly be weighed and measured.
The optimal weight to height ratio would be loosely defined - give or take 15%. Anything above or below 15% starts changing the person's prices for the worse. Being underweight would affect the price for the worst as well.
All businesses would have to play along. This would be mandatory by law.
A person who has a valid medical reason for their weight to height ratio being way off can obtain an exemption card in the same way handicapped people do. If they have the card, they pay standard prices for any goods and services that would otherwise be affected by the weight-to-height ratio.