E-Kidney | DECEMBER 2012

Obesity and the Kidneys: Research Update

There are more reasons to sound the alarm about the growing childhood and teen obesity epidemics in America, according to new research linking adolescent obesity to kidney disease. Obesity has long been known to cause both high blood pressure and type-2 diabetes, two of the leading causes of kidney disease, and also forces the kidneys to work harder to filter out toxins and to meet the metabolic demands of the increased body mass index (BMI). Previously though, most research had emphasized the link between adult obesity and kidney disease.

According to Joseph Vassalotti, MD, Chief Medical Officer of the National Kidney Foundation, “Maintaining a healthy weight is not just an issue of vanity or physical perception – an optimal weight promotes health, prevents chronic diseases, and fosters longevity."

In a new study led by Asaf Vivante, MD of the Edmond and Lily Safra Children's Hospital, Sheba Medical Center, overweight and obese teens were approximately three to seven times as likely to develop kidney disease later in life. This study examined BMI and its link with kidney disease in over one million adolescents.

BMI, a number calculated based upon weight and height to measure one’s body fatness, is considered a good indicator of whether or not one’s weight is within a healthy range. The ideal range for BMI is 18.5-24.9. According to the study, the teens that fell into the categories of overweight (25-29.9) or obese (≥30) during adolescence were much more likely to develop kidney disease approximately 30 years later. Interestingly, the research demonstrated an increased risk for kidney disease even in those who did not develop diabetes.

According to Lynda Szczech, MD, National Kidney Foundation Immediate Past President, "This study is important because it really shows us that everything is on a continuum. If you have diabetes, you are at risk for kidney disease. If you are at risk for diabetes, this also increases your risk for kidney disease. The link between obesity and kidney disease should be taken seriously and we need to do the best that we can with our diet and exercise choices every day. As adults we need to teach ourselves and our children that making healthy lifestyle choices and maintaining a normal weight matters; as parents we must lead by example. We may not be ‘perfect’, but each time we focus a little bit of attention on our health and making better choices we are taking a step towards keeping our families healthy."

In order to treat obesity and protect the kidneys, the National Kidney Foundation recommends that people who are overweight and obese focus on three main lifestyle areas: diet, exercise and sleep. Here are some quick tips for each:

1. Diet: Follow a healthy diet and focus on eating smaller portions. Drink water rather than sugary drinks, which contribute to overall calories consumed without filling you up. Since consuming excess protein increases the kidneys’ work load, eat the recommended amount of protein (0.8 gram/kg/body weight). Limit sodium intake to 2,300 milligrams/day for healthy young people and 1,500 milligrams/day if over age 50, or if you have diabetes, high blood pressure or CKD.
2. Exercise: Physical activity is essential. It burns calories which helps promote weight loss and maintain a healthy weight over time. Set a goal. Work towards two hours and thirty minutes of moderate-intensity exercise each week. This can be spread out over the week and broken down into intervals of 20-30 minutes or even less.
3. Sleep: Getting a good night’s sleep also promotes a healthy weight. For most people about seven hours of sleep each night constitutes an adequate amount. Many studies suggest that irregular sleep patterns, eating before going to bed and short sleep duration are all linked to obesity and weight gain.