KOCHI: Obesity has grown into a global epidemic, affecting nearly every corner of the world. According to 2022 data from the World Health Organisation (WHO), 43 per cent of adults were categorised as overweight, with 16 per cent classified as obese. Closer to home, India’s National Family Health Survey (NFHS-5) revealed a concerning trend: 40 per cent of women and 12 per cent of men exhibit abdominal obesity.
While obesity is widely recognised for its role in metabolic diseases like diabetes and cardiovascular disorders, its direct impact on kidney health is often underappreciated. However, evidence reveals that the kidneys are not just passive participants but key organs at risk due to obesity.
Increased metabolic demand
As body weight increases, so does the metabolic demand. This heightened demand leads to elevated pressure within the kidneys, specifically in the filtering units called glomeruli. To adapt, the kidneys undergo compensatory glomerular hyperfiltration, which can result in protein loss in the urine — a condition termed proteinuria — even in individuals without prior kidney disease.
Chronic kidney disease (CKD)
Obesity dramatically increases the risk of developing CKD. Research shows individuals with a Body Mass Index (BMI) exceeding 30 are three times more likely to develop CKD compared to those with a healthy BMI. For patients already diagnosed with kidney disease, obesity accelerates the decline in kidney function.
Kidney transplant outcomes
Obesity complicates outcomes in patients with advanced CKD who require transplantation. Post-transplant survival rates are poorer in obese individuals, underscoring the need for maintaining a healthy weight.
Kidney stones
Obesity also predisposes individuals to kidney stone formation. Alterations in urinary pH, coupled with increased levels of oxalate, uric acid, and sodium in the urine, create an environment conducive to stone formation. Insulin resistance, a hallmark of obesity, exacerbates the risk. Interestingly, bariatric surgery, often pursued to combat obesity, can also elevate the risk of calcium oxalate stones by increasing oxalate reabsorption in the gut.
Kidney cancer
Emerging evidence links obesity with kidney malignancies, including renal cell carcinoma. Around 10 per cent of all kidney cancers are attributed to excess weight, making obesity a significant risk factor.
Effects of decreasing BMI on kidneys
Studies show that a 3 per cent reduction in BMI was associated with significant reduction and even remission of proteinuria over 6 months in around 30 per cent. Improvement was also reflected in the lipid profile of these people. Over two years of consistent decrease in BMI was associated with proteinuria remission in around 55 per cent of patients.
The broader picture
Obesity often exists as part of a larger metabolic syndrome, accompanied by diabetes and systemic hypertension, which are well-known culprits of kidney damage. However, the direct effects of obesity on the kidneys emphasise that the impact goes beyond these associated conditions.
A call to action
The intricate relationship between obesity and kidney health serves as a clarion call for proactive measures. Adopting a balanced diet, engaging in regular physical activity, and seeking medical advice for weight management can go a long way in safeguarding kidney health. As the saying goes, “Lose fat, save kidneys!” A healthier weight isn’t just about aesthetics — it’s a cornerstone of preserving our vital organs.
The writer is a specialist at SP Medifort, T’Puram