A country whose citizens collectively succeeded in losing weight and increasing their level of physical activity saw their health improve and death rates plunge.

In a unique natural experiment, researchers have observed how a nation that lost an average of 5kg per head over five years contributed to a halving of the death rate from diabetes and a one third reduction in deaths from heart disease.

The natural experiment occurred in Cuba which was plunged into crisis in the early 1990s following the collapse of the Soviet Union. Its experience demonstrates what could be achieved elsewhere if the same changes could be brought about, without an economic crisis.

Food and fuel were in short supply in Cuba from 1990 resulting in millions going hungry and having to abandon their vehicles and walk.

Cars and buses virtually disappeared from the roads as fuel supplies dried up, and farmers had to abandon motorised machines and work the fields manually. The Government issued one million bicycles to keep the population on the move.

Between 1990 and 1995, the average Cuban consumed fewer calories than they expended each day, leading to an average weight loss of 5kg.

Deaths from diabetes began to fall in 1996, five years after the start […]