From the Globalance Investment Commentary (Wealth Cockpit):
The term «biomass» dates back to the 1920s and means the total mass of living organisms (measured in kilos). In the past, «biomass» was mainly used with reference to plants and animals. It primarily served to estimate the Earth's annual «output» available as a resource to humans.
However, the term is now also used in connection with the human population. The development of human biomass has a significant impact on the consumption of global resources (e.g. food) and the footprint left by our species.
In 2005, the combined biomass of all the Earth's adults was around 290 million tonnes, with the average grown-up weighing 62 kg. However, there were, and still are, considerable geographical disparities. One tonne of human biomass corresponds to around 12 adults in North America and 17 adults in Asia. But what would happen if increasing prosperity and an alignment of consumer needs produced an adjustment in overall human weight?
A recent study looked at this. If the total world population had the BMI distribution of the USA, the increase in weight would be equivalent to an extra 1 billion people (see chart). Given that population projections suggest that by 2050 there could be an additional 2 billion people on the planet, this figure is highly significant.
Source: BMC Public Health, 2012