Some diets and diet pills may cause further kidney damage in overweight adults

Analysis adds to concerns about weight-loss methods and dietary protein intake

With 1 in 5 overweight Americans suffering from chronic kidney disease, Cleveland Clinic researchers analyzed the nutritional and lifestyle habits of overweight adults, finding that their methods included diets and diet pills that may cause further kidney damage.

The study findings, published online this month in the International Journal of Obesity, came from an analysis of food choices and lifestyle habits of 10,971 overweight adults taken from the National Health and Nutrition Examination Survey (NHANES), a federally-administered assessment of the overall health and nutritional status of Americans.

Of the overweight and obese patients with kidney disease included in the survey, 50 percent reported that they had attempted to lose weight in the past year. The survey showed that, on average, obese Americans with kidney disease consume protein in amounts that are above the recommended levels prescribed by the National Kidney Foundation for chronic kidney disease patients.

The typical American diet each day includes approximately 1.2g of protein per kilogram of body weight. Patients with CKD are advised to consume 0.6g to 0.75g protein per kilogram of body weight each day and popular high-protein diets may call for up to 1.9g per kilogram of body weight.

"People who are overweight or obese are at higher risk for chronic kidney disease and there is a great need to define what the appropriate lifestyle changes and weight loss modalities are for protecting kidney function," said Sankar Navaneethan, M.D., a nephrologist in the Glickman Urological and Kidney Institute at Cleveland Clinic and lead author of the study. "Rather than using fad diets or diet pills, overweight and obese people with kidney disease may adopt a weight loss plan that incorporates a low-protein, low-calorie diet, regular physical activity and close follow-up by their physicians."

The survey asked patients whether they participated in regimens that included diet or exercise or both, but the specific program, such as a high-protein diet or low-protein diet, was not named. The survey also found that eight percent of weight loss seekers with CKD used medications as part of their weight loss regimen. Certain weight loss methods, especially high-protein diets and weight loss medications are not recommended in people with kidney disease as they may lead to further kidney damage.

The authors recommend further studies designed to identify safe treatment strategies for weight loss with regards to protecting kidney function.

According to the Centers for Disease Control and Prevention, more than 10 percent of adults aged 20 or older in the U.S., or more than 20 million people, have chronic kidney disease (CKD), a condition that describes the progressive worsening of kidney function. It is often found in patients who have diabetes or hypertension, and can exist without symptoms until it progresses to severe levels. When CKD progresses to end-stage renal disease, patients typically require treatment through dialysis or transplantation. The prevalence of the disease is rapidly growing as is the cost burden. Medicare costs in the U.S. for the care of patients with end-stage renal disease has risen from $12.2 billion in 2000 to $20.8 billion in 2007.

Source: Cleveland Clinic