The health harms of obesity are well known. Carrying extra weight, especially around your middle, can increase the risk for type 2 diabetes, heart disease, stroke, and even some types of cancer, according to the Centers for Disease Control and Prevention (CDC).
But how much obesity causes these conditions has been relatively unknown and unexplored. Now, a study published in October 2016 in PLoS Genetics is shining light on the toll of obesity, along with how extra weight may affect men and women differently.
“We found that obesity is involved in two-thirds of the leading causes of death, meaning that we as a society need to become better at preventing obesity,” says Jenny Censin, MD, researcher at Nuffield Department of Medicine at the University of Oxford in England, and first author of the study.
Using a scientific model that enabled them to determine a causal relationship between obesity and additional health outcomes, Dr. Censin’s team found that in women extra weight increased the risk for type 2 diabetes more than in men. Meanwhile, in men extra weight elevated the risk for chronic kidney disease and chronic obstructive pulmonary disease (COPD) more than in women.
“These findings indicate that the effects of obesity differ between men and women, which is something we need to learn more about so that we can optimize disease prevention for both men and women,” she says.
Obesity is a growing health crisis, both in the United States and around the world. According to the World Health Organization (WHO), worldwide obesity has nearly tripled since 1975; in the United States, the CDC’s National Health and Nutrition Examination Survey (NHANES) estimates that 39.6 percent of adults are obese.
How Obesity Is Associated With Chronic Disease and Early Death
A wealth of research, including a past prospective study that followed more than 1 million adults over 14 years, shows a strong association between obesity and the risk of death from all causes.
For example, a panel of experts commissioned by the Obesity Society in 2012 reviewed all the existing evidence on obesity and health risks. In an article published in the journal Obesity, they concluded that obesity is a disease that causes functional impairment and reduced quality of life, serious disease, and more early deaths.
Yet determining the degree to which factors such as obesity, high cholesterol, smoking, or high blood pressure cause a condition or early death is tricky. “It can be difficult to establish the causes of any disease, because other factors can muddy the water and lead us to the wrong conclusions,” says Censin.
Clarifying the causes of disease is critical because it enables doctors to focus on the right thing when it comes to disease prevention, she says. “One way to be more certain that something truly causes a disease is to use an approach called Mendelian randomization, a method that uses genes that individuals carry naturally in order to tease out the causes of disease,” says Censin.