Politicians could do more to tackle the spread of obesity, a new series of studies suggests.
Governments are being urged to encourage better eating habits by supporting financial incentives to enable production of healthier foods, such as subsidised fruit and vegetable production and levies on calorie-rich foods.
Local authorities are also being called upon to promote creation of neighbourhoods that allow residents easy access to good local parks and shops, encouraging people to be more active.
The research findings, collated in a book by a University of Edinburgh scientist, suggests that broad changes to the environments in which people live have contributed to a rise in obesity in recent decades, with increased use of cars, lack of local green space and an abundance of cheap, high-calorie foods.
Dr Jamie Pearce, of the University of Edinburgh's School of GeoSciences, co-editor of the book 'Geographies of Obesity', said: "People know they should eat well and take exercise but this can be difficult in practice - all too often fast food is readily available but there is little local access to healthy food, while often the easiest way to get around is by car.
"Authorities could do more to change the way entire populations live, at an international, national and local level, making it easier for people to eat well and be active. Doing a little could make a big difference."
Over the past two decades, rates of adult and childhood obesity in the developed world have risen sharply. In the year 2000, 65 per cent of Americans were overweight, and 30 per cent were obese. Obesity raises the risk of diabetes, cancer, heart disease, and high blood pressure.