If you listen to popular opinion at all, you might be scared off from doing things that are actually healthy for you. From mid-20th century doctors saying lifting weights can lead to heart problems and lower sex drive, to modern “experts” claiming children shouldn’t lift weights, to fears of people doing deep squats, even to women being warned that strength makes them look bulky. You name it, it’s been said. And a lot of it is untrue. Today we’ll take a look at the most common part of dieting among athletes: the high-protein diet.
While our guide is designed to be informative, it is not medical advice. These opinions shouldn’t be used for diagnosis, prevention, or treatment of any kind of health problem. If you think you have an illness or medical condition, talk to a medical professional. In fact, you should always talk to your doctor before changing your diet or training protocol in a significant way. Also, stay on top of regular check-ups.
So let’s get back to it. Have you heard people say that high-protein diets are bad for your kidneys? But what about all those men and women in the gym lifting weights and drinking protein shakes? Are they really doing all that to harm their bodies? Nope, but let’s dive into this a bit.
What is a High Protein Diet?
Next we should define what we mean when we say high protein diet. It could be defined in different ways. One way is to define it as a percentage of total calories; other times, it’s defined as grams per pound of bodyweight. The cutoffs and parameters can be quite arbitrary and can vary by field, researcher, or consensus.
The RDI says it should be 0.36 grams per pound of bodyweight, which is basically 0.8 grams per kilogram. If you’re in the strength game, you’re likely more familiar with it being 1 gram of protein per pound of bodyweight to help reduce soreness plus grow and maintain muscle, each and every day. This equals 200 grams for a 200-pound person.
This doesn’t mean this is the optimal amount of protein for everyone to consume — you may be able to make do with much less — but that’s the most common number we hear.
High Protein Diet: Is it Bad for the Kidneys?
This idea gained in popularity after a few studies were published in the 1980s and 1990s claiming that the higher amounts of protein people consumed, the greater their glomerular filtration rate (GFR) was, which is a marker for kidney waste filtration. Scientists said that a higher GFR meant the kidneys were under a lot of stress.
Later studies revealed this wasn’t true for people with healthy kidneys.
There is also a lot of research out there in regards to athletes. A crossover study of males who were resistance training found that those who consumed three grams per kilogram of bodyweight (nearly 1.5 grams per pound) experienced no harmful effects on their liver or kidney function. Another bodybuilding study said those who consumed more than 1.3 grams per pound of body weight experienced zero problems with how their kidneys flushed urea, creatinine, and albumin.
While eating a high-protein diet full of protein powder is likely not bad for you, if you have unhealthy kidneys, it could be. Your doctor may recommend a restricted protein diet if you have kidney damage, because lots of protein may slow its progression.
Dr. Trevor Kashey, biochemist and nutritionist, puts it this way: while running is not bad for you, it is if you have a broken leg.
However, just because something made a condition worse, does not mean it caused it. High protein will not lead to kidney problems unless the person has a kidney problem. In this case, the problem could get worse.
Some kidney problems, such as chronic kidney disease (CKD), are asymptomatic and progressive. By the time you have symptoms, all the damage has already been done, and high protein consumption could have worsened it.
Kidney problems don’t occur in isolation. If you are already diabetic, overweight, have high blood pressure, or have certain genetic issues related to kidney function, you may be at a higher risk of kidney problems. Stick to your regular yearly physicals to stay on top of this.
You may wonder how much protein you should have, how many times a day you should have it, and what the amino acid profile is. So the recommendation for 1 gram per pound of bodyweight being bad for the kidneys is just not true.
If you are healthy and are sticking to regular check-ups, high protein won’t be an issue so mix up that protein shake!