Here’s How Much Protein You Really Need in a Day, with a Kidney Doctor’s Wisdom
How much protein do you need? A recent study suggests that on average, Americans are eating twice as much than is good for us. Here's a reliable formula.
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You’ve probably seen plenty of it on social media: the body-building posts, the “how it started vs. how it’s going” weight loss memes; the “What I Eat in a Day” videos (as if we’d all actually morph into identical shapes if we ate the exact same foods as each other). A high-protein diet is one approach to fitness that a lot of influencers promote, and maybe that’s no wonder—high protein intake is popularly associated with weight loss, muscle-building, tissue repair, and getting leaner overall.
But when we load our plates with meat, snack on multiple protein bars a day, and drink our protein shakes in the name of health, it’s important to keep in mind: as with pretty much anything we humans do for short-term gains, too much of this powerful macronutrient can cause long-term health problems you might not realize.
Sure, protein can slim down your waistline to showcase that beach bod you’ve worked so hard for (a little abs definition is no small feat!). However, eating too much protein can be tough on your kidneys—vital organs for filtering and cleaning the blood. And lately, it’s arguable that our collective love affair with protein has officially become too much: a 2020 study published in the peer-reviewed Journal of the American Society of Nephrology (JASN) reveals the average consumption of protein in the U.S. is nearly twice as much as the recommended daily intake.
Does a diet too high protein hurt your kidneys?
Dr. Kamyar Kalantar-Zadeh, MD, MPH, PhD—a nephrologist and lead researcher of the JASN study—says, “High-protein intake overburdens the functional units of the kidneys that filter and clean blood.”
Especially for low-carb living, eggs at breakfast, chicken for lunch, or a juicy sirloin for dinner are considered to be disciplined diet choices. But clinical professionals like Dr. Kalantar-Zadeh advise pumping the brakes on protein intake to reduce strain on your kidneys. As Dr. Kalantar-Zadeh explains, “When we eat excess protein, more toxic waste products need to be removed by the kidneys, causing them to be overworked. Otherwise, these waste products accumulate in the blood, leading to chronic kidney disease (CKD).”
To put this another way, Brittany Lubeck, RD, a registered dietitian, explains: “Protein is a rather complex substance that takes your digestive system longer to break down and your kidneys longer to filter.”
Excess protein harms your kidneys, but the type of protein you eat matters, too. Animal protein sources contain higher amounts of purines—chemical compounds broken down by the body to form uric acid (a toxic waste product in your blood). Having too many waste products in your blood means the kidneys will have to work overtime to flush them out of your system.
You’re practicing good nutrition, but there’s always more to learn—read Dietitians Just Shared 6 Tips to Help Your Gut Absorb Vitamin D.
What do high levels of protein in the kidneys mean?
The irony is that as you eat more protein for its health benefits, excessive amounts accumulate in your blood and eventually your kidneys. Too much protein in your kidneys can cause protein to leak through your kidneys’ filters and into your urine—a condition called proteinuria, which can be a sign of damaged kidneys, according to information published by the American Kidney Fund.
It’s normal to have a small amount of protein in your urine, but too much can be a sign of a more severe condition. For example, the JASN study indicated that “excess protein in your kidneys over time can lead to CKD, kidney stones, and high blood pressure.”
Is kidney damage from too much protein reversible?
If you’re starting to panic thinking back on all the delicious protein-rich foods you’ve enjoyed, here’s some good news: you can reverse kidney damage that hasn’t progressed to CKD. Lubeck says if your healthcare provider catches kidney damage before it progresses too far, it may be possible for you to undo the damage quite easily. For some people, all it takes is proper nutrition, hydration, and healthy lifestyle habits.
So how much protein do you need? The amount depends on various factors, such as age, weight, gender, and activity level. However, the JASN study notes that the standard recommended daily allowance (RDA) for protein is 0.8 grams per kilogram of body weight per day. You may want to discuss this with your healthcare provider, but generally healthy adults can trust this recommendation. The researchers in the JASN study explained that this amount is calculated to meet the requirements of 97 to 98 percent of the population. (Learn how dietitian Lubeck suggests you might consider spacing your protein throughout the day by reading Craving Sugar? A Dietitian Says You May Need More of This Surprising Nutrient.)
While minding your overall protein intake is a top priority for kidney health, Dr. Kalantar-Zadeh and his team recommend increasing your proportion of plant-based protein to animal protein. They suggest consuming half to two-thirds of your protein from plant sources to help prevent or slow the progression of kidney disease.
According to the National Kidney Foundation, eating the right amount of protein helps control the build-up of waste products in your blood, so your kidneys don’t have to work so hard. Conversely, if protein intake is too low, you can encounter other problems…so eating the right amount each day is essential.
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- Dr. Kamyar Kalantar-Zadeh, MD, MPH, PhD: Nephrologist, Chief of Division of Nephrology, Hypertension and Kidney Transplantation at University of California School of Medicine.
- Brittany Lubeck, RD: Registered dietitian and nutrition writer.
- Journal of the American Society of Nephrology: "The Effects of High-Protein Diets on Kidney Health and Longevity"
- American Kidney Fund: "Protein in Urine (Proteinuria) Causes, Symptoms, & Treatments"
- National Kidney Foundation: "Nutrition and Early Kidney Disease"