The Growing Link Between High BMI and Chronic Kidney Disease

Credit: Adobe Stock/Ralf Kalytta

Chronic kidney disease (CKD) affects millions of people worldwide and can lead to serious health problems, including kidney failure. A new global study has found that while CKD rates have been gradually increasing for decades, kidney problems linked specifically to high body weight are growing much faster — and are projected to keep climbing until at least 2050.

According to the American Kidney Fund (AKF), an estimated 35.5 million people in the United States alone have kidney disease, making it the country’s fastest-growing noncommunicable disease. Maintaining a healthy weight, staying active, following a kidney-friendly diet and getting tested for kidney disease are all key steps for prevention.

A body mass index (BMI) of 25 or higher is considered overweight, and 30 or higher is considered obese. Excess weight can put extra strain on the kidneys, increasing the risk of CKD over time.

“Epidemiologically, quantifying the disease burden associated with modifiable risk factors such as obesity is essential for understanding its relationship with CKD,” wrote lead investigator Weihong Zhao, of the division of nephrology at Jiangsu Province Hospital and Nanjing Medical University First Affiliated Hospital in China. “However, CKD burden attributable to obesity, especially in epidemiological patterns and dynamic changes, remains unclear.”

Zhao and team analyzed data from 204 countries covering the years 1990 to 2021 from the Global Burden of Disease (GBD) Study 2021. They focused on CKD cases, deaths and years of healthy life lost (called disability-adjusted life years, or DALYs) related specifically to high BMI.

What the Study Found

In 2021, CKD caused over 1.5 million deaths globally. Nearly 420,000 of those deaths — about 27% — were linked to high BMI. High BMI was also responsible for more than 10.4 million DALYs.

When comparing 1990 with 2021, deaths from CKD related to high BMI increased 3.5 times, and DALYs nearly tripled. The rise was seen in both men and women, but men had slightly faster growth rates.

Looking Ahead

The study projects that CKD deaths and disability linked to high BMI will continue to rise steadily through 2050. While men and women are expected to have similar rates, the total number of cases will likely be higher among women.

Investigators also looked at why CKD rates are climbing. They found that population aging, growth and changes in disease patterns all play a role. Aging, in particular, has a big impact in higher-income regions.

By taking steps to keep your weight in a healthy range, you can reduce the strain on your kidneys and lower your risk of developing CKD. With obesity rates climbing worldwide, this study is a wake-up call for both individuals and public health systems to take action.

Investigators mentioned some important limitations, including basing the findings on observational data, as they can’t prove that high body weight directly causes CKD. It also only used BMI to measure obesity, which doesn’t distinguish between muscle and fat or show where fat is stored in the body. In some countries, limited health care resources may lead to missed or incorrect CKD diagnoses, meaning the true number of cases could be higher. In addition, the CKD diagnosis was based on estimated kidney function tests that may be less accurate in certain populations.

“Given that obesity is a modifiable risk factor, targeted weight reduction policies and interventions tailored to specific age groups, sexes, and regional contexts should be encouraged in the future,” concluded investigators.