How does weight affect your kidneys? Exploring the link between obesity and kidney health

The kidneys are two bean-shaped organs located just below the rib cage, on either side of the spine. Each is about the size of an adult fist. The kidneys play a vital role: they filter the blood, helping to remove waste products and maintain a healthy balance of water, salts and minerals. They also control the production of red blood cells, manufacture vitamin D which plays an important role in maintaining bone health.

In kidney disease, the kidneys are damaged and cannot function as effectively as normal. If the damage is sudden or temporary, it is called ‘acute’ disease. When the damage develops over a longer period of time it is called ‘chronic kidney disease’ (CKD). Kidney disease can be caused by many different conditions, including obesity. It is important to be aware of this potential risk as people living with obesity can take steps to reduce the risk of developing kidney disease.

There is a strong link between obesity and CKD. Obesity is associated with a higher risk of developing high blood pressure, high blood sugar and type 2 diabetes , which in turn can be key risk factors for developing CKD. These risk factors can damage the blood vessels in kidneys thus affecting the normal functioning of the kidneys. Click here for or further information on the link between high blood pressure and obesity Similarly, in people with diabetes, high levels of blood sugar can slowly damage the kidneys and this can reduce their ability to filter blood. Click here for or further information on the link between diabetes and obesity

Excess body fat can also have a direct impact on the kidneys even in those who do not have diabetes or high blood pressure. It can trigger a range of reactions in the body, including long-lasting inflammation in the fatty tissues. This can lead to scarring in the glomeruli, tiny filter units in the kidneys, making it harder for them to filter the blood effectively.

Obesity can also lead to changes in the blood flow that can increase pressure on the kidneys, making it harder to pump blood through the veins.

In the early stages of CKD there are few signs and symptoms and any symptoms that do occur are often non-specific and may be caused by other conditions. Please consult a healthcare provider if you experience the following symptoms:

• nausea and vomiting
• loss of appetite
• fatigue
• urinating more or less frequently
• swelling of feet and ankles
• dry itchy skin
• decreased mental alertness.

If you live with obesity, it is sensible to discuss your risk factors for CKD with your doctor. Obesity related CKD is currently diagnosed by measuring BMI, urine and blood tests and bioscopy, so you may wish to ask your doctor whether you should be tested.

The good news is that you can take steps to target both obesity and CKD. These include:

• Making changes to your routine as part of a weight management plan (such as increasing amount of physical activity) can reduce inflammation and oxidative stress in patients with moderate to severe CKD
• Carefully following instructions on dosage of over-the-counter medications, particularly pain relievers, such as aspirin, ibuprofen and acetaminophen. Taking too many pain relievers over a long period of time can lead to kidney damage.
•  Work with your doctor to manage other conditions that may affect your kidney health, such as diabetes or high blood pressure

If you or a loved one are living with obesity and have concerns about kidney disease, contact a health professional to discuss the way forward.