If there's some balance to the diet, and not over-consuming lean meat it should be fine. Most of the people I know on OMAD don't have any kidney issues.

Care to explain why this would give someone kidney stones? I've been on a variation of the 5-2 diet (eat 5 days a week, fast 2 days a week) for about 7 years. I've had kidney stones once in my life but it was years before I ever tried fasting/keto/5-2.

Does eating only once a day contribute to kidney stones?