The most likely explanation is the abundance of food versus the population size. The population in 1750 was less than in 1900 so the amount of food per head was greater thus leading to a better diet and, not to put too fine a point on it, chubbier figures. However you do have to consider the localized famines in 1750. This led to some having rather gaunt figures though others became bloated with starvation.
In 1750, the population of the world was 629 million people. By the year 1950, the population had increased to 2.52 billion.
About 140 million in 1750 and 180m in 1800.
15,000.
Lame
Villages in 1750, towns in 1850.
Villages in 1750, towns in 1850.
Villages in 1750, towns in 1850.
600,000 or so.
About 250,000
About 50,000.
In 1750 population of russia was 23 million