In less than a generation, rates of child obesity have risen dramatically worldwide. For example, in the US children weigh on average 5kg more than they did 30 years ago, and one in three children is now overweight or obese, researchers wrote in The Lancet journal.
    
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, researchers noted.
    
New research estimates suggest that US children are consuming an average of 200 kilo calories per day more than they were in the 1970s, and that this is USD 400-worth of food per child per year, or USD 20 billion a year for the US food industry.
    
In low- and middle-income countries, stunting still affects over a fifth of children under 5 years of age, but obesity is rapidly rising, creating a double nutritional burden that 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, researchers said.
    
"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," said co-author Dr Tim Lobstein, from the World Obesity Federation.
    
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.
    
Yet, few countries have taken regulatory steps to protect children from the negative health effects of obesity or implemented widely recommended healthy food policies.
    
Most have relied solely on voluntary moves by the food industry, with no evidence of their effectiveness.
    
Researchers call 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.

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