Too much and kidneys

Is protein dangerous?

By GyroscopeUpdated November 15, 20268 sources

Not at the amounts people eat, if your kidneys are healthy. Across 28 studies and then 22 trials, eating more protein made healthy kidneys filter more, with no sign of damage, though most of those trials were short. The exceptions are kidney disease, where your doctor sets the number, and a history of kidney stones. A 2025 advisory also says to avoid more than 2 g per kg a day for long periods.

The worry has two sources. One is that people with kidney disease are told to eat less protein, so it sounds like protein hurts kidneys. The other is the jump in protein advice: when the US range went up in January 2026 and gyms talk about a gram per pound, it’s fair to ask whether more can turn into too much.

We’d eat anywhere in the typical range of 1.2 to 1.6 g per kg without a second thought, and a bit above it if you lift hard. We see no reason to go past about 2 g per kg for long, because the muscle trials didn’t find extra gains up there and the 2025 advisory says to avoid it. If you have kidney disease, or have had kidney stones, ask your doctor first. The Gyroscope app personalizes yours.

A healthy kidney filtering more after a high-protein meal is a bit like your heart beating faster on a walk. It’s the organ doing more work for a while, and in the trials that’s all it looked like.

What the kidney trials found

The US has no upper limit for protein. The National Academies didn’t set one, and the scientific report behind the 2025 to 2030 guidelines says “no upper limit for dietary protein has been established”. So far no study has found the point where harm starts in healthy people, and no study has shown that any amount is safe either.

The 2 g per kg line

The strongest caution comes from the 2025 joint advisory on nutrition for people on GLP-1 drugs, written by four groups including the American Society for Nutrition and the Obesity Society. It says protein “should not fall below 0.4–0.5 g/kg/day, as this can lead to muscle atrophy and functional impairments, while prolonged intake above 2 g/kg/day should be avoided due to potential adverse health effects.”

It doesn’t say in that line which effects it means. We take it as a sensible ceiling for everyday eating, and it lines up with the muscle evidence. In the biggest review of lifting trials, extra muscle leveled off near 1.6 g per kg, and 2.2 was the top of the uncertainty. For most adults, 2 g per kg is a lot of food: 165 g a day at 180 lb.

Who should be careful

• People with kidney disease. The 2024 international kidney guideline (KDIGO) suggests 0.8 g per kg a day for stages 3 to 5, and avoiding more than 1.3 g per kg in adults at risk of getting worse. Your doctor sets your number, and this site gives no range for you. More in protein with kidney disease.
• People who don’t know. The CDC says more than 1 in 10 US adults (14%, 37 million people) have chronic kidney disease, and about 9 in 10 of them don’t know it. If you plan to eat at the top of the range for good and haven’t had your kidney numbers checked in a while, ask for the test at your next checkup.
• People who’ve had kidney stones. The 2025 advisory says people with a history of kidney stones should be counseled to avoid high-oxalate foods, highly processed foods and animal-source proteins.
• People on a GLP-1 who can’t keep fluids down. The same advisory says dehydration from nausea, vomiting or diarrhea can injure the kidneys. Fluids come first, and call your prescriber.
• Pregnancy. The US RDA is the reference, 71 g a day in the second half. See protein in pregnancy.

The protein isn’t the whole package

Most of the health worry about “high protein” is really about the foods it comes in. The 2025 advisory encourages beans, peas, lentils, whole grains, dairy, seafood, eggs and lean poultry, with red and processed meats “considered in moderation or minimized given links to type 2 diabetes, cardiovascular disease, and colorectal cancer in general populations”. Getting more of your protein from fish, dairy, eggs, poultry, beans and soy covers that.

Protein powders are a separate question about what else is in the tub. smoothie.guide covers the lead in protein powder worry, and processing.guide asks whether protein powder is ultra-processed.

If someone told you a number that sounds high, put it in someone said X grams is enough and see where it lands for your weight.