One reason to maintain a healthy body weight is to prevent diseases. But keeping your weight within normal limits is also good for the environment.
Food production is a major contributor to global warming. A population that maintains a healthy body weight consumes almost 20 per cent less food and produces fewer greenhouse gases than a population in which 40 per cent of people are obese.
According to scientists at the London School of Hygiene and Tropical Medicine, transport-related emissions would be lower because it takes less energy to transport slim people.
They estimate that a population of 1 billion lean people would emit 1 billion tonnes less carbon dioxide equivalents per year than an overweight one.
In nearly every country in the world, the average body mass index (BMI) is rising.
Populations across the world including Hong Kong are getting bigger - 21.6 per cent of the adult population in 2004 were overweight compared with 22.2 per cent in 2008.
