Obesity among adults rises at unprecedented pace globally

The past 40 years have seen an unprecedented increase in the number of obese adults worldwide, climbing to about 640 million from 105 million in 1975. If the trend continues, about one-fifth of adults will be obese by 2025.

The rate has more than doubled for women and tripled for men, according to a new analysis published in the Lancet. Under the present trajectory, the chance of meeting a goal set by the World Health Organization to halt the increase over the next decade is, according to the study, “virtually zero.”

Behind the global spike is greater access to cheap food as incomes have risen. “It’s been very easy, as countries get out of poverty, to eat a lot, and to eat a lot of unhealthy calories,” said Majid Ezzati, the study’s senior author and chair of global environmental health at Imperial College London. The price of fresh fruits, vegetables and whole grains often are “noticeably more than highly processed carbohydrates,” he said.

A person who has a body mass index higher than 30, or weighs at least 203 pounds and is 5 feet 9 inches tall, is considered obese. The world population’s average weight has increased by about 3.3 pounds per decade since 1975, the researchers estimate. Excess weight raises the risk of diabetes, heart disease and other chronic conditions.

Governments need to prepare for the jump in medical costs that accompany unhealthy weight and focus on prevention now to avoid higher costs in the future, said Bill Dietz, director of the Sumner M. Redstone Global Center for Prevention and Wellness at George Washington University.

“They should be as nervous as a cat on a hot tin roof about the tsunami of diabetes that’s coming their way,” Dietz said. “The cost of this rise in the prevalence of obesity is going to be staggering.”

Working under the banner of the Non-Communicable Disease Risk Factor Collaboration, Ezzati and hundreds of colleagues from around the world gathered data from surveys that measured the height and weight of 19 million adults. They then used statistical methods to estimate trends in global and national weight patterns from 1975 to 2014.

The main takeaway? Excess weight has become a far bigger global health problem than weighing too little. While low body weight still is a substantial health risk for parts of Africa and South Asia, being too heavy is a much more common hazard worldwide.

The Lancet analysis also estimates an alarming rise of extreme cases of obesity. The global rate of severe obesity, or BMI higher than 35, is on pace to surpass 9 percent in women and 6 percent in men by 2025. That category now includes 39 million adults in the United States In 1975, it was 4 million.

Meeting the WHO target of halting the rise in obesity by 2025 “will require action of monumental proportions,” Boyd Swinburn, a professor of population nutrition and global health at the University of Auckland in New Zealand, said in an e-mail.