Will too much protein damage my kidneys? Cause cancer? Reduce my lifespan? At Precision Nutrition we’re always getting questions (from fitness pros and clients) about the risks of a high-protein diet. In this article we’ll set the record straight and share why protein isn’t the villain it’s made out to be.

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Maybe you’re a protein promoter.

You buy protein powder in “bucket with a handle” format. You know the protein counts of every food you eat.

After every workout, you jam those amino acids into your cells. You swear you can feel them getting swole.

Or maybe you’re a protein avoider.

Maybe you’ve heard bad things.

Like: Protein will damage your kidneys.

Or: Protein will give you cancer.

Or simply: We all eat too much protein.

Maybe you want to lose fat. Or gain muscle. Or be healthy.

You just want to do the right thing and eat better. But with conflicting information about protein, you don’t know what to think.

Or, if you’re a fitness and nutrition coach, you’re wondering how the heck to clear up the confusion about protein among your clients.

Let’s get into it.

In this article, we’ll explore:

• What are high-protein diets?
• What does the evidence say about high-protein diets and health?
• Does protein source matter?
• How much protein is right for me?

How to read this article

If you’re just curious about high-protein diets:

• Feel free to skim and learn whatever you like.

If you want to change your body and/or health:

• You don’t need to know every detail. Just get the general idea.
• Check out our advice at the end.

If you’re an athlete interested in performance:

• Pay special attention to the section on athletic performance.
• Check out our advice for athletes at the end.

If you’re a fitness pro, or interested in geeking out with nutritional science:

• We’ve given you some “extra credit” material in sidebars throughout.
• Check out our advice for fitness pros at the end.

Why protein?

A quick intro if you aren’t a nutrition pro:

• Protein is one of the three main macronutrients that makes up the food we eat. (The other two are fat and carbohydrate.)

• Protein itself is made up of amino acids.

• Amino acids are the building blocks for most stuff in our bodies. They’re like Legos that can be broken down and re-assembled in different ways.

• Unlike extra fat (which we can store very easily on our bums and bellies),we don’t store lots of extra amino acids. Protein is always getting used, recycled, and sometimes excreted.

• If we don’t get enough protein, our body will start to plunder it from parts that we need, such as our muscles.

• So we have to constantly replenish protein by eating it.