Over one in eight adults are now obese -- a ratio that has more than doubled since 1975 and will swell to one in five by 2025, a major global survey reported Friday.

Of about five billion adults alive in 2014, 641 million were obese, said an article in The Lancet medical journal-- and the number is projected to balloon beyond 1.1 billion in just nine years' time, with serious consequences for global health.