It’s not really news that Americans’ level of overweight and obesity is one of the highest, if not the highest in the world, but it is news how the rest of the world is ‘trying’ to catch up. That’s just one aspect of a new report by the GBD 2015 Obesity Collaborators just published in The New England Journal of Medicine.
The Global Burden of Disease Study is a global observational epidemiological study that aims to quantify global risks to health from major diseases, injuries and risk factors. It’s run under the auspices of WHO and funded by the Bill and Melinda Gates Foundation.
Using BMI  as their metric, the collaborators assessed data from 195 countries — essentially the global population — to quantify the prevalence of overweight (BMI between 25 and 29) and obesity (BMI 30 and up) among children (younger than 20 years) and adults. In all, data from over 68 million people were included, and trends in prevalence between 1980 and 2015 were established. Since 1980, the investigators found, the prevalence of obesity in more than 70 countries has doubled — and has increased in most of the others.
They then assessed the effect of high BMI on health outcomes.
Worldwide, over 100 million children and over 600 million adults were obese in 2015. And the prevalence of obesity was about 5 percent in children, and 12 percent in adults. The unfortunate finding was that obesity was increasing more rapidly in children than adults.the rate of increase in obesity in children was greater than that for adults.
In general, women were more likely to be obese than men, with peak levels occurring between 60 and 64 years in the former and between 50 and 54 years for the latter.
The sociodemographic index (SDI) is a measure of a country's level of development; the p[revalence of obesity, for both men and women, increased along with the SDI — the higher the level of development, the greater rates of obesity for children and adults, as indicated in the graph below.
The authors found that high BMI contributed to 4 million deaths from various causes — with cardiovascular disease being the leading cause, and diabetes the second leading cause of BMI-related mortality.
Perhaps the most concerning statistic in the current report was that between 1980 and 2015, there was a significant relative increase of 20 percent in the prevalence of obesity in countries with low SDI — that is developing countries. It’s a major concern since such countries likely don’t have the advanced medical care available to deal with the sequelae of obesity (e.g., pharmaceutical or surgical means).
In addition to the above statistics, this study found that the BMI-related mortality was lowest at BMIs of 20-25, and showed a continuous increase in the risk of death at higher BMIs. This contradicts other reports that found a lower risk with BMIs in the overweight category (i.e. BMI 25-29).
These authors concluded: “Our results show that both the prevalence and disease burden of high BMI are increasing globally. These findings highlight the need for implementation of multicomponent interventions to reduce the prevalence and disease burden of high BMI.”
And probably the most efficient way to decrease the future global burden of obesity will be to focus efforts on the young.
 BI: Body Mass Index —weight in kg/height in meters 2 . While a poor indicator of fatness in individuals, BMI is useful on the population level as it is used here.