Why we get overweight

Doctors speak of a time bomb: by 2030, half of the world's population will be overweight or obese. Obesity causes a rapid increase in diabetes, cardiovascular diseases and cancer - and is becoming the most serious health problem worldwide.
Why has no country managed to stop this epidemic? According to the food industry and government agencies, it is due to a lack of individual self-discipline. Is that correct? The documentary 
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