Understanding the link between obesity, fatty liver disease and kidney stones provides a new perspective on prevention and potential treatment.Kidney stone disease is increasingly recognized as a chronic condition closely tied to metabolic health, with obesity standing out as a major risk factor. Conditions such as diabetes, hypertension and cardiovascular disease are closely associated with the development and recurrence of kidney stones.
Kyle Wood, M.D., associate professor in the University of Alabama at Birmingham Department of Urology, details the link between obesity and kidney stones and what this could mean for the future of kidney stone research and treatment options.
A chronic condition
Kidney stone disease is revealing itself as a chronic condition closely linked to metabolic health. Traditionally, kidney stones were regarded as singular events rather than symptoms of an ongoing metabolic imbalance.
“Once we shift the mindset of practitioners and health care providers to really think of kidney stones less as an episodic issue but more as a chronic issue, then we will be able to start tackling it as a chronic disease,” Wood said.
Obesity increases risk
Obesity is a metabolic disorder that increases the risk of various health problems such as heart disease, diabetes and hypertension and is a significant risk factor for kidney stones.
“With obesity, there is an increase in usually two types of stones,” Wood said. “There is an increase in both calcium oxalate stones and uric acid stones.”
The formation of uric acid stones is strongly linked to insulin resistance — a hallmark of obesity and diabetes.
“As insulin resistance develops, it alters urine composition,” Wood said. “One key change is a drop in urine pH, making it more acidic. This acidic environment promotes uric acid stone formation.”
Calcium oxalate stones occur more frequently in obese individuals, though the mechanism is multifaceted.
“It raises the question ‘Why does obesity increase kidney stone risk?’” Wood said. “We know that, as body mass index [BMI] and waist circumference increase, urinary oxalate excretion also rises.”
Collaborative research with Amy Goss, Ph.D., assistant professor in the Department of Nutrition Sciences, and the Nutrition and Obesity Research Center suggests that this excess oxalate comes from both dietary sources and the body’s own production.
“We’ve investigated whether high-oxalate foods are responsible or the body is generating more oxalate internally,” Wood said. “Our findings suggest that obesity influences both factors.”
Ongoing research: Fatty liver disease and kidney stones
One of the newest areas of research is the connection between fatty liver disease — now referred to as metabolic-associated steatotic liver disease, or MASLD — and kidney stone formation.
“We’re pioneering research that links fatty liver disease to kidney stones,” Wood said. “Oxalate, a key component in many kidney stones, originates in the liver, which means metabolic disturbances in the liver could influence stone formation.”
Since obesity increases the likelihood of developing MASLD, this condition may be a missing link in understanding why obese individuals have a heightened risk of kidney stones. Rather than obesity alone being the primary factor, it may be the underlying metabolic dysfunction, such as fatty liver disease, that plays a key role.
Addressing obesity as a root cause — through weight management, dietary changes and metabolic research — could lead to better strategies for reducing kidney stone risk in the future.