You only have to open your eyes to see that the world is getting fatter.

Health officials — some of whom call overweight and obesity a global pandemic — say that the increasing availability of processed foods is simply overwhelming humanity. Combine that with high-tech sedentary lifestyles and more disposable income and the table is set for packing on extra pounds.

But just how bad is the problem? A new big-data study published in The Lancet, a medical journal, lays out the kind of vast and sweeping survey that would have been unimaginable in the days before affordable computing power. It's basically a global headcount of overweight people.

An international team of researchers led by Marie Ng, PhD, an assistant professor of global health at the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, collected data from 188 countries' national health ministry surveys and other sources (1,770 in all) from 1980 through 2013 and gleaned from it age, gender, heights and weights, worked some statistical hocus-pocus on the data and came up with some eye-popping trends.

China is now second only to the US in obesity, with its numbers bulging in the past three decades to 46 million adults qualifying as obese and 300 million overweight. China has a way to go to catch up to the US, however. The survey found that the US accounts for 13 percent of the world's obese, while the vast populations of China and India combined make up only 15 percent of the world's total obese.

The study used the BMI metric — the body mass or weight-to-height ratio — to assess overweight (25-30) and obesity (30 and above). The Hospital Authority of Hong Kong, as an example, calls a BMI of 18.5 to 22.9 normal, 23 to 24.9 overweight at risk, 25 to 24.9 moderately obese and over 30 severely obese.

Worldwide, overweight and obesity combined rates rose by 27.5 percent for adults and 47.1 percent for children from 1980 to 2013. The total number of overweight and obese individuals increased from 857 million in 2008 to 2.1 billion in 2013.

The study also found some interesting sex patterns. In developed countries, more men than women were overweight or obese; in developing countries, overweight or obese women outnumbered men.

In China, 23 percent of boys under 20 fall into the category of overweight or obese, while only 14 percent of girls under 20 make it. Of men 20 and older, 28.3 percent are overweight; and among women 20 and older, 27.4 percent are in the group.

By contrast, in the US, 28.8 percent of boys under 20 are overweight, but significantly, 12.4 percent are obese. Among US girls under 20, 29.7 are overweight, with 13.4 percent obesity. Among US men 20 or older, a whopping 70.9 percent are overweight or obese; and 61.9 percent of women 20 or older, with 33.9 percent of the total qualifying as obese.

The Wall Street Journal reported that China's armed forces are feeling the pinch, "with the People's Liberation Army facing challenges as its soldiers have begun to have trouble fitting into traditionally-sized tanks".

Ng said the high percentages of overweight and obesity in China were "especially troubling. We need to be thinking now about how to turn this trend around".

The greatest gain in weight worldwide, the survey found, came between 1992 and 2002 and mainly among people aged 20 to 40, for some reason. The rate of weight gain in recent years has been slackening off in the last eight years, but, no countries have shown any significant decrease in obesity prevalence in the past 30 years.

Much of the original data was what's called "self-reported", the kind of personal facts people might give over the phone, and as one might suspect, can be subject to exaggeration. As the paper puts it: "Self-reported weights for women in some countries tend to be under-reported and self-reported heights for men tend to be over-reported." In other words, women fudge their weight and men fudge their height.

"These data are all heavily modeled," the Lancet editors explain, "so that the real data are inevitably somewhat obscured, but the truth is not."

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