Kidney stones, hardened mineral deposits that form in the kidneys, affect a significant portion of the population and can cause severe pain and complications. More than 10% of men in the United States experience kidney stones, which are lumps of minerals that collect in your kidneys and travel into your ureter, where they block the flow of urine. The relationship between weight loss and kidney stones is complex and multifaceted. While obesity increases the risk of kidney stones, certain weight loss strategies can also elevate this risk. Managing weight through proper diet and lifestyle modifications is crucial for preventing kidney stones and maintaining overall health.
Obesity and Kidney Stones: Understanding the Link
Obesity is a chronic health condition characterized by having a high amount of body fat. Its prevalence is increasing in the United States, with health survey data finding that the rate of obesity increased from 30.5% in 1999-2000 to 41.9% in 2017-2020. Obesity can increase your chance of kidney stones. Experts don’t know exactly why this is, but losing weight may help lower your chance of developing them. Several factors contribute to this increased risk, including changes in urine composition, increased inflammation and oxidative stress, and dietary patterns associated with obesity.
Changes in Urine Composition
Obesity alters urine composition, making it more conducive to stone formation. As insulin resistance develops, it alters urine composition,” Wood said. “One key change is a drop in urine pH, making it more acidic. People with obesity often have lower urine pH, which promotes the formation of uric acid stones. The formation of uric acid stones is associated with a low urinary pH, low urinary volume, and hyperuricosuria. Low urine pH has a larger impact on stone formation than urate excretion. This acidity is thought to be due to a defect in ammonia excretion in the nephron. It has been suggested that insulin resistance may impair the transport of ammonia into the proximal tubular lumen as a consequence of attenuation of the Na+/H+ exchanger (NHE3). A defect in mitochondrial metabolism of glutamine to glutamate and subsequent conversion to alpha-ketoglutarate that generates ammonia in the proximal tubule cells may be contributory. This could have a dual effect, causing an increase in uric acid via recycling extra glutamine into the production of purines. Decreased urine volume can result in an increased concentration of substances that predispose patients to uric acid kidney stone formation. High urinary concentrations of solutes, such as urate, can result in uric acid precipitation. This is supported by the observed trend that uric acid stones are more prevalent in hotter and more tropical environments where there may not be access to clean water, resulting in dehydration from diarrhea.
Inflammation and Oxidative Stress
Increases in inflammation and oxidative stress associated with obesity may increase the likelihood of kidney stone formation. Fatty tissue, which is abundant in obesity, is an endocrine organ that is a source of adipokines and inflammatory cytokines that contribute to the insulin resistant, proinflammatory, prothrombic, and a prohypertensive state. Enhanced systemic inflammation and increased inflammatory cytokines in the small intestine have been reported in murine models of obesity which might augment oxalate absorption. Exposure to high concentrations of oxalate as well as calcium oxalate and calcium phosphate crystals for extended periods of time can cause injury to renal epithelial cells. Crystals bind rapidly to the surface of epithelial cells and are internalized. Lower levels of oxalate promote cell growth whereas higher oxalate levels induce cell damage and death. Fatty acid overload may result in the accumulation of triglycerides in non-adipose tissue, including the kidney.
Dietary Factors
Certain dietary patterns, such as a higher intake of calories, in people with obesity may elevate the chance of kidney stones. Kidney stones develop when you eat too many foods that contain high amounts of sodium, trans fats, additives, and poor-quality proteins. Eating in moderation while maintaining a healthy diet with fruits and vegetables is encouraged. High intakes of sodium and animal proteins can increase the risk of stone formation.
Read also: Weight Loss Guide Andalusia, AL
Weight Loss Strategies and Kidney Stone Risk
While losing weight can help reduce the risk of kidney stones associated with obesity, some weight loss methods can paradoxically increase this risk. It’s also possible that losing weight may elevate your kidney stone risk in some cases. However, research on this topic is limited. Using extreme diets or certain types of fad diets to lose weight may increase kidney stone risk.
Extreme Diets and Fad Diets
Extreme diets and fad diets can disrupt the body's metabolic balance and increase the risk of kidney stones.
Bariatric Surgery
A 2023 study found that bariatric surgery was associated with an over six-fold risk of kidney stones afterward. However, the authors noted that this was likely due to physiological changes associated with the surgery and not the weight loss itself. Bariatric surgery can lead to malabsorption and changes in urine composition, increasing the risk of hyperoxaluria (high levels of oxalate in the urine) and stone formation.
Weight Loss Medications
Some weight loss medications can also increase the risk of kidney stones. Orlistat, a lipase inhibitor used for weight loss, results in accumulation of fat in the intestine that binds calcium by saponification that may augment intestinal oxalate absorption, resulting in increased urinary oxalate excretion, the latter increasing stone risk.
Dietary Strategies for Weight Loss Without Increasing Kidney Stone Risk
To minimize the risk of kidney stones while losing weight, it's essential to adopt a balanced and sustainable approach to diet and lifestyle. Dr. Penniston emphasizes that there is no magical one-size-fits-all diet for weight loss and stone prevention, and the key lies in finding a sustainable approach that works for each individual.
Read also: Beef jerky: A high-protein option for shedding pounds?
Hydration
Drinking plenty of water is crucial for preventing kidney stones. Extra water dilutes the substances in urine that lead to stones. However, water and other healthy beverages lowers your risk if you drink about two liters per day. Increased fluid intake helps dilute urine, reducing the concentration of minerals that form stones.
Balanced Diet
Focus on a diet rich in fruits, vegetables, and whole grains while limiting sodium, animal proteins, and processed foods. In contrast, eating the “right” foods helps prevent kidney stones and also helps you lose weight. Modify the DASH diet so you can enjoy foods from your culture or your childhood by creating healthier versions of them.
Calcium Intake
Ensure adequate calcium intake, as calcium binds to oxalate in the gut and reduces its absorption into the bloodstream. Calcium doesn’t cause kidney stones. It’s more common than you think.
Limit Oxalate-Rich Foods
If you are prone to oxalate stones, limit your intake of foods high in oxalate, such as spinach, rhubarb, and nuts.
Reduce Sodium Intake
High sodium intake increases calcium excretion in the urine, which can contribute to stone formation. Kidney stones develop when you eat too many foods that contain high amounts of sodium, trans fats, additives, and poor-quality proteins.
Read also: Inspiring Health Transformation
Moderate Protein Intake
Excessive protein intake, especially from animal sources, can increase uric acid levels and the risk of stone formation.
The Role of Exercise
Regular physical activity is essential for weight management and overall health. If you’re obese, you may find it difficult and cumbersome to move around. However, moving around eventually helps you shed your pounds and become more mobile. Not only does exercise burn off fat when you do it hard enough to sweat, the sweat helps dissolve your kidney stones.
Finding the Right Exercise
Dr. You might also choose to work with a trainer or physical therapist while you move from obese to overweight to a healthy, stable weight. A trainer helps you find the right kind of exercise for your current fitness level, then ups your game as you lose the pounds. If you’re not able to hire a trainer or join a gym, find a friend or family member who can be a workout partner.
Managing Complex Dietary Scenarios
Certain medical conditions and medications can complicate dietary management for kidney stone prevention.
Post-Gastric Bypass Hyperoxaluria
Patients who have undergone gastric bypass surgery often present with hyperoxaluria due to reduced gastric volume, leading to low urine volume and high urine oxalate.
Malabsorptive Diseases
Patients with malabsorptive diseases like Crohn's face difficulties in controlling urine oxalate levels despite limited oxalate intake.
Medications Like Topiramate
Some patients on medications like topiramate for migraines experience low urine citrate, requiring meticulous efforts to counteract stone formation.
Diabetes
Dr. Monga highlights the difficulties faced by diabetic patients in balancing stone prevention with their dietary restrictions and the challenge of incorporating fruits into their diets.
Ketogenic Diets
Dr. Penniston lastly addresses patients on ketogenic diets, who often have acidic urine due to high protein and acid load, necessitating alkaline strategies.
The Importance of Personalized Approaches
Due to the challenges of counseling patients on weight loss and dietary changes, Dr. Penniston stresses the need for personalized approaches.
Individualized Diet Plans
Work with a registered dietitian or healthcare provider to develop a personalized diet plan that addresses your specific needs and medical conditions.
Metabolic Variations
Recognize that metabolism varies between individuals, and what works for one person may not work for another.
Sustainable Lifestyle Changes
Focus on making sustainable lifestyle changes that you can maintain long-term rather than following restrictive diets.
The Kidney Stone Center at The Miriam Hospital
The Kidney Stone Center at The Miriam Hospital is the only center of its kind in Southern New England. If you have a kidney stone, we can help.