Recent reports warning of an obesity epidemic stress the need to tackle the problem early by focusing on children.
The UK's National Obesity Forum has published a report on the situation in Britain, while independent thinktank the Overseas Development Institute has written about the global position. Both reports call on governments to do more, pointing out that increasingly sedentary lifestyles are contributing just as much as diet to health problems such as heart disease, diabetes and stroke.
The National Obesity Forum's report says that physical education in schools is part of the solution, but adds that care must be taken when promoting competitive sport not to deter those who are not so keen on it, as this could result in "children either returning to or increasing their sedentary lifestyle".
A report from the Organisation for Economic Cooperation and Development, meanwhile, shows that fewer than one in four children report participating in regular moderate-to-vigorous exercise.
According to Health at a Glance 2013, boys are more likely to take part in regular physical activity than girls. Activity wanes for both genders as they get older, the only exceptions being boys in Italy and the US.
In Europe, 2011-12
Activities on the curriculum for students under 14 and the number of countries where they are mandatory
Ball games 27
Health and fitness 19
Outdoor and adventure 18
Winter sports 5
Source: Physical Education and Sport at School in Europe, figure 2.2, Eurydice. bit.lyPEinEurope.