Washington, Feb 19 (IANS): Global progress towards tackling obesity has been "unacceptably slow," with only one in four countries implementing a policy on healthy eating up to 2010, reveals a major six-part series on obesity by a global team of researchers.

Published in the prestigious journal The Lancet, it says that in less than a generation, rates of child obesity have risen dramatically worldwide.

Although child obesity rates have started to level off in some cities and countries, no country to date has experienced declining rates of obesity across its population, the series added.

In the US, children are consuming an average of 200 kilocalorie (kcal) per day more than they were in the 1970s, and that this is $400 worth of food per child per year, or $20 billion a year for the US food industry.

"Fat children are an investment in future sales," said series co-author Tim Lobstein from London-based World Obesity Federation.

In low- and middle-income countries, stunting still affects over a fifth of children under five years of age, but obesity is rapidly rising, creating a double nutritional burden.

It can affect the same population and the same individual - for example poorly-nourished infants who do not develop their full height but do gain more than their full weight.

"This highlights the importance of ensuring a supply of food that encourages healthy growth and that is not jeopardised by the aggressive marketing of cheap, less nutritious products by multinational food companies," the series authors wrote.

"Undernutrition and overnutrition actually have many common drivers and solutions, so we now need to see an integrated nutrition policy that tackles both these issues together," Lobstein added.

The food industry has a special interest in targeting children.

Repeated exposure to highly processed foods and sweetened drinks during infancy builds taste preferences, brand loyalty and high profits.

This year, the global market for processed infant foods is expected to be worth a staggering $19 billion, up from $13.7 billion in 2007.

Yet, few countries have taken regulatory steps to protect children from the negative health effects of obesity or implemented widely-recommended healthy food policies, the authors emphasised.

"Our understanding of obesity must be completely reframed if we are to halt and reverse the global obesity epidemic," stressed Christina Roberto from the Harvard University's T.H. Chan School of Public Health.

The series authors have called for food policies that change the nature of the food and consumer environment including the availability, price and nutrition standards of food products and the marketing practices that influence food choices and preferences.