Tackling obesity is one of the World Health Organisation's top priorities - and one of its greatest challenges.
At the organisation's World Health Assembly last month, director-general Margaret Chan told delegates that "not one single country has managed to turn around its obesity epidemic in all age groups".
Childhood obesity is associated with a greater chance of premature death and disability in adulthood. It can also create difficulties during childhood, with an increased risk of high blood pressure and insulin resistance, among other problems.
The World Health Organisation has pointed out that children in low- and middle-income countries are more vulnerable to inadequate nutrition. But at the same time, they are exposed to high-fat and high-sugar food, which tends to be cheaper. This can result in sharp increases in childhood obesity, while nutrition issues remain unresolved.
According to the organisation, in 2010, 42 million children under the age of 5 were overweight. More than 80 per cent of them lived in developing countries.
In the US, the proportion of children aged 6-11 who were obese increased between 1980 and 2010 from 7 per cent to nearly 18%
Over the same period, the proportion of adolescents aged 12-19 who were obese increased from 5 per cent to 18%
Source: Centers for Disease Control and Prevention.