Matt Ridley discusses free-market solutions to obesity. One section caught my attention:

In due course, the obesity problem will be solved, I suspect. The ultra-rich have already solved it. Most of them are very thin these days, quite unlike in ancient times. That's because they can afford the solutions that work for them, from low-carb diets to personal trainers.

If economic growth continues to spread, as it has over the past two centuries, most people will be ultra-rich by today's standards within two generations, and slim figures will also spread. Still, it would be nice to find a way for people to lose weight without having to wait for them to get rich first.

The signifiers of wealth evolve over time. In some countries a tan is a signal of wealth because it means you can afford to vacation where there's sun. But in Asia a dark complexion was often a signal that you were in a lower socioeconomic class and forced to work out in the sun all day, for example in farming or construction, so a pale complexion was socially desirable.

In places of food scarcity, obesity can be a sign of wealth. However, in the U.S. today, it's the reverse: the wealthy can afford to hack the diet and lifestyle issues that lead to obesity in poorer socioeconomic groups.