Origins of epidemic go back decades earlier than previously thought.
Over the past 50 years, worldwide obesity rates have tripled, creating a public health crisis so widespread and damaging that it is sometimes referred to as an epidemic. Most accounts put the roots of the problem firmly in the modern age. But could it have been brewing since before World War II?
That’s one provocative conclusion of a study published today in Science Advances that purports to
push the obesity epidemic’s origin back to as early as the 1930s. Historical measurements from hundreds of thousands of Danish youth show that in the decades before the problem was officially recognized, the heaviest members of society were already getting steadily bigger.
The findings raise questions about the accepted narrative of the obesity epidemic, says Lindsey Haynes-Maslow, an obesity expert at the University of North Carolina at Chapel Hill who was not involved in the study. “This paper is an opportunity … to say maybe we’ve been looking at this wrong, maybe we should go back to the beginning—or, when
was the beginning?” she says.
Most epidemiologists trace that beginning to the 1970s, when health officials first observed an uptick in the prevalence of obesity—defined as a body mass index (BMI) above 30—in many Western nations. The crisis is usually blamed on the increased postwar availability of cheap, highly processed, and calorie-rich foods, as well as increasingly sedentary lifestyles and growing portion sizes.
But University of Copenhagen epidemiologist Thorkild Sørensen was skeptical of that story. Years of slowly increasing body size typically precede obesity, and might show up in historical data, he suspected. And Sørensen wasn’t convinced that the so-called obesogenic diet and lifestyle were the only factors at play. Historical data, he hoped, could reveal whether other, yet-unknown factors had contributed to the crisis.
A dearth of BMI data from before the 1970s typically makes historical studies of obesity a challenge. But Sørensen and his team knew of two Danish government data sets that could be useful. The first consisted of meticulous records of the weight and height of practically all primary-age schoolchildren in Copenhagen between the 1930s and ’80s. The second contained similar measurements of men, ages 18 to 26, who were conscripted by the Danish army between 1957 and 1984. The records were promisingly rich—but they were all on paper, which made it impossible to systematically search them for patterns. The process of digitizing the more than 2 million measurements from all 526,115 subjects took years of work, Sørensen says.
https://www.science.org/content/article/origins-obesity-epidemic-may-be-further-back-we-thought
