Obesity and Kidney Stones

Weight gain and obesity appear to increase the risk of kidney-stone formation, particularly among women, according to a report published in the January 26, 2005, issue of JAMA.

A group of researchers performed a prospective study of three large cohorts: 45,988 subjects in the Health Professionals Follow-up Study, 93,758 older women in the Nurse's Health Study I, and 101,877 younger women in the Nurse's Health Study II.

Over a combined 46 years of followup, investigators documented 4,827 cases of kidney stones. When age, diet, and other variables were accounted for, a man who weighed more than 220 pounds had more than 1.4 times the risk of developing kidney stones as a man weighing 150 pounds, according to researchers. The effect was stronger among women, with overweight women having nearly twice the risk of kidney stones. A similar link was observed between kidney stones and waist circumference. The differences seen among the overweight and obese cannot be explained by dietary factors, according to the authors.

“For now, clinicians have an additional reason to encourage weight control in their patients,” the authors conclude.