WTF Is A ‘Complete Protein’ Anyway?

Whoa, good to know.

Christine Byrne |

Unless you’ve been living under a rock without internet for the last five years… you probs know by now that protein is really, really important for your body. It’s essential for building and preserving muscle—super important for your overall health, even if you’re not trying to get swole—and can help with weight loss.

But dive deep into paleo forums on Reddit (or do any research on a vegan diet), and things about protein get way more complicated. There are all kinds of confusing new things to worry about, including something apparently important called complete proteins. But… what does that mean, exactly?

READ MORE: 13 Foods With More Protein Than An Egg

A protein is a “complete” protein if it has all nine essential amino acids.

The short version: “A complete protein contains all of the amino acids we have to consume or cannot create on our own,” explains dietician Erik Bustillo.

In case it’s been a while since grade 9 bio: Proteins are made up of a combo of “building blocks” called amino acids. There are 20 total different amino acids, and your body needs all of them to repair tissue, grow new tissue, break down food, and basically to be in tip-top form.

Of these 20, nine are called “essential” amino acids, meaning your body can’t make them on its own, according to the National Institutes of Health (NIH). And if you can’t make them on your own, you need to eat them. They are:

  • Histidine
  • Isoleucine
  • Leucine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan
  • Valine

The remaining 11 (called “nonessential” and “conditional” amino acids) are produced by your bod on its own, so a healthy person doesn’t have to worry about getting them from food.

READ MORE:9 High-Protein Vegetables That Will Fill You Up Fast

A complete protein basically has all nine of those essential, can’t-live-without-them amino acids in it—and in one fell swoop, helps you ensure that your body is getting all of the protein-related nutrients that it needs to function properly.

All animal proteins—meat, fish, dairy, and eggs—are complete proteins, says Bustillo. “Soy protein is also considered a complete protein.”

Examples of “complete” proteins

  • Cheese
  • Fish
  • Meat
  • Eggs

READ MORE: Here’s Exactly How Much Protein You Should Be Eating Every Day

Sorry, vegans, but plant-based proteins generally aren’t considered “complete”.

Options like beans, grains, nuts and seeds have some but not all of those nine essential amino acids, says Bustillo. One of the few exceptions to this is soy. That’s why plant proteins are called “incomplete.”

Examples of “incomplete” proteins

  • Beans and legumes
  • Whole grains
  • Nuts
  • Seeds

Good news: If you’re on a plant-based diet, you’re NOT totally screwed in the protein department.

…You just need to be a bit more strategic with your protein sources to make sure you’re getting all of the important nutrients you need.

Basically, if you’re on a plant-based diet, you should be pairing together two different types of incomplete proteins to get all of those essential amino acids. This is called making a complementary protein.

Obviously, it’s really hard to know what kinds of food have what amino acids. Keep this rule of thumb in mind, says Bustillo: Pair a legume (like beans, peas, lentils, or peanuts) with a grain, nut, or seed to make a complete protein.

READ MORE: 20 High-Protein, Low-Carbohydrate Foods Everyone Should Be Eating

  Some of Bustillo’s fav combos include:

  • Brown rice and beans
  • Peanut butter and bread (a classic!)
  • Hummus and pita

You should be eating complete proteins in some form every single day.

The amount of protein intake per day varies by person and depends on factors like your weight and your fitness goals. In general, a 64kg woman should be eating about 50 grams of protein every day.

But regardless of how much protein you’re supposed to be eating, you need to be making sure you’re getting it from complete sources—whether it’s animal protein or complementary plant-based proteins. “Ideally, we’d get [all nine essential amino acids] in the same meal to have a more synergistic effect,” says Bustillo.

READ MORE: This Is How Much Protein Is In A Cup Of Quinoa

If you’re struggling with that on a vegan diet, good news: According to the National Institute of Health, it’s not absolutely necessary to pair complementary proteins together in a single meal. However, you should still be eating those complementary proteins over the course of the day. Getting all of your protein from a single plant source just won’t cut it. Bustillo recommends supplementing with a complete protein powder as well as getting smart about your protein pairings.

The bottom line:Animal proteins are complete proteins, but most plant proteins are not. So make sure you’re getting protein from a wide variety of sources so that you’re giving your body (and muscles!) the best fuel possible.

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