The findings emphasize the importance of excess weight as a risk factor for chronic kidney disease (CKD).
Because many populations across the globe continue to gain excess weight, Richard Silverwood, PhD, Dorothea Nitsch, MD (London School of Hygiene and Tropical Medicine, in England), and their colleagues conducted a study to see what sort of effect being overweight or obese might have on kidney health.
The researchers analyzed information from the Medical Research Council National Survey of Health and Development, a sample of children born in one week in March 1946 in England, Scotland, and Wales. A total of 4,584 participants had available data, including body mass index at ages 20, 26, 36, 43, 53, and 60 to 64 years.
They found that participants who were overweight beginning early in adulthood (ages 26 or 36 years) were twice as likely to have CKD at age 60 to 64 years compared with those who first became overweight at age 60 to 64 years or never became overweight.
The link between overweight and CKD was only in part explained by taking diabetes and hypertension into account.
Larger waist-to-hip ratios ("apple-shaped" bodies) at ages 43 and 53 years were also linked with CKD at age 60 to 64 years.
"We estimated that 36 percent of CKD cases at age 60 to 64 in the current US population could be avoided if nobody became overweight until at least that age, assuming the same associations as in the analysis sample," said Dr. Nitsch.
"To our knowledge we are the first to report how age of exposure to overweight across adulthood may affect kidney disease risk," she added.
It is unclear whether the timing of overweight onset or the duration of being overweight drives the link with CKD seen in the study. Either explanation suggests that preventing excess weight gain in early adulthood could have a considerable effect on the prevalence of CKD.
Doing so appears to have a larger effect than any treatment for CKD known to date, the researchers said.
The study will appear in an upcoming issue of the Journal of the American Society of Nephrology (JASN).