(Good Medical Health) – With or without existing kidney disease, kidney function is likely to deteriorate over time, plus a person is severely obese, according to a large study.

The analysis reveals that people with the most severe obesity are twice as likely to develop kidney failure as adults who are simply overweight. People who are not as obese have a higher risk of developing kidney function reduced from 18 to 69%.

"Excess weight, especially around the belly, causes many adverse metabolic effects on the kidney," said Dr. Alex Chang, lead author of the Danison Geisinger Health System study, in a statement. Pennsylvania.

This overweight can activate the body's sympathetic nervous system, or "fight or flight" response, which releases hormones that can increase sodium retention and blood pressure, Chang said via email. This also makes it harder for the body to eliminate extra sugars in the blood, which leads to diabetes.

All of these things are detrimental to the kidneys and inflammation related to obesity and excessive abdominal fat can also impair kidney function, Chang said.

"First of all, being overweight increases the activity of the sympathetic nervous system and the hormones that result in increased sodium retention and higher blood pressure," Chang said. "Second, excess weight decreases the body's ability to move blood glucose into cells and can lead to diabetes." Abnormal levels of hormones and inflammation related to belly fat can also harm the kidneys, he said.

"Although this study does not directly address the prevention, reversal, or slowing of kidney disease, the management of risk factors such as hypertension, diabetes, and high cholesterol is important. "said Chang. "For obese people, weight loss can reverse these metabolic abnormalities and may help reduce the future risk of kidney disease."

Globally, 1.9 billion adults are overweight or obese, according to the World Health Organization. About 4 out of 10 adults are overweight and more than 1 in 10 are obese, a condition that, in addition to kidney problems, can also increase the risk of heart disease, diabetes, joint disorders and certain cancers.

For the current analysis, researchers examined data collected from 1970 to 2017 on over 5.4 million adults in 40 different countries in Asia, Europe, the Middle East, and North America. . They also examined data from more than 84,000 people at high risk for cardiovascular disease and more than 19,000 adults with chronic kidney failure. On average, individuals were followed for about 8 years, and the researchers looked for people who had undergone tests showing a reduction in their renal function during this period.

To understand the impact of obesity on kidney function, researchers focused on body mass index (BMI), a weight-for-height ratio.

A BMI between 18.5 and 24.9 is considered a healthy weight, while 25 to 29.9 is overweight, 30 or more is obese and 40 or more is what is called obesity severe or morbid. (The US National Institute of Heart, Lung and Blood has a BMI calculator online here: bit.ly/1D0ZqDv).

The study compared the probabilities of declining renal function in people with overweight and obesity to varying degrees.

One of the limitations of the study is that researchers only studied BMI at a given time, note the authors of the study in The BMJ. It is also not known whether obesity has directly caused kidney problems, or whether other factors such as inactivity or unhealthy eating may have played a role.

"A poor diet, eating a lot of processed foods and lack of exercise can certainly contribute to both obesity and kidney damage," said Dr. Michal Melamed of the College of Medicine Albert Einstein and Montefiore Medical Center in New York.

"This may be the underlying cause of the link between obesity and kidney damage, the fact that obese people have other lifestyle habits that can contribute to kidney damage," said Melamed, not involved in the study, by e-mail. "But, above all, lifestyle factors can be changed."

SOURCE: bit.ly/2DJfxPN The BMJ, online January 10, 2019.