Last week, we started our 4-week Protein Talk Series. In week one, we broke some of the most common myths about protein. This week, let's talk about complete and incomplete proteins.
You can find protein in many foods, but not all proteins are the same. There's distinction between complete and incomplete proteins, and it's important to know what is what so you can make best choices for your body.
Let's clear up the confusion!
Essential and Non-Essential Amino Acids
To understand the differences between complete and incomplete proteins better, we first have to understand a bit more about amino acids that proteins are made of.
I know, I promised last week that there will be no boring biochemistry involved in these Protein Talks, but let's get a few important things out of the way (it really takes just a second!) and then get to the part that you're probably actually here for, which is how to make sure that you actually get the best quality proteins into your body.
So, proteins consist of amino acids. There are two main types of amino acids: essential and non-essential. The essential amino acids are the ones that our bodies can't produce on their own, so we have to get them from food.
The non-essential type of amino acids are the ones that our bodies produce on their own.
Accordingly, complete proteins are the ones in which you can find all essential amino acids (there's 9 of them). Incomplete proteins are the ones that lack one or more of the essential amino acids.
Where To Find Complete Proteins
The most common sources for complete proteins, e.g the ones that provide you with all the essential amino acids, are the following:
- other dairy products
It's a bit harder for vegetarians and vegans to meet their daily protein requirement, because there are just some too many non-animal foods in which you can find complete proteins. There are some though:
- chia seeds
- hemp seeds
However, if you look at the amount of protein found in these non-animal foods, you realize that you'd need to eat a lot of them to get even close to the amount of protein that you'd get from eating animal sources. Here are a few examples:
- 1 cup cooked ground chicken – 35 grams of protein, 300 kcal
- 1 cup cooked ground turkey – 35 grams of protein, 295 kcal
- 1 cup cooked lean ground beef – 32 grams of protein, 305 kcal
- 1 cup cooked quinoa – 8 grams of protein, 222 kcal
- 1 cup cooked amaranth – 9 grams of protein, 251 kcal
Also hemp and chia seeds are sources of complete protein, but it's really difficult to eat enough of these foods to cover your protein needs. Protein content of the most typical serving sizes, 2 tbsp, is not exactly amazing:
- 2 tbsp chia seeds – 4.7 grams of protein, 137 kcal
- 2 tbsp hemp seeds – 10 grams of protein, 80 kcal
Using chia seeds or hemp seeds as your complete protein source is not enough. You probably don't eat all that much of them–sprinkling a few tablespoons on your morning oatmeal is the way most people use them, but we need much more than that. It's really important to get enough protein with your first meal of the day, but if it's less than 10 grams, it's way too low.
What's Wrong With Soy
Soy and products made of soy are also known as sources of complete protein. Here are a few nutritional facts about soy products, like tofu and edamame:
- 1/2 cup tofu – 10 grams of protein, 94 kcal
- 1 cup edamame – 17 grams of protein, 189 kcal
However, you should be careful using too much soy in your diet, and it definitely shouldn't be your main source of protein. Soy has phytoestrogens in it, which mimic estrogen in our bodies (but are actually not). Phytoestrogens are associated with breast cancer, endometriosis and infertility.
Another reason why you shouldn't consume soy that often is that it can be potentially harmful for your thyroid. Have you noticed that so many people nowadays have thyroid issues? If you're one of them, you should be very careful with soy. Soy is goitrogenic food, and goitrogens are known to prevent the thyroid from getting the necessary amount of iodine.
Soy can also inhibit vitamin and mineral absorption, so even if you're eating your veggies and other nutrient-dense foods, you may not be able to get all the great benefits from them if you're eating lots of soy at the same time.
Are Incomplete Proteins Useless?
By eating complete sources of protein like the ones listed above, you make sure that your body gets all nine essential amino acids that it needs for working properly.
But that doesn't mean that incomplete proteins are useless. Amino acids that may be missing from one food could be made up by eating another food that has those amino acids. For example, if you're fine with eating legumes and grains, you could pair rice and beans or peanut butter and whole wheat bread. Forming complete proteins that way is possible, but it takes some work.
You don't have to eat both sources of these foods at one meal if you don't want to, it's enough if you're able to do it by the end of the day. So for example, you may eat one of those foods at lunch and other at dinner. But as said, figuring out the right pairs can take quite a bit of work and effort–eating complete protein sources is definitely easier option.
What Happens If You Don't Eat Complete Proteins?
Protein has many functions, which we talked about last week. It helps your muscles to repair after a hard workout, it helps to digest foods and it provides you with energy. If you want to lose fat or build muscle or both, taking care of your protein intake is the number one thing you need to keep in check in your nutrition.
If you're getting your protein from incomplete sources only, all those functions will slow down. Your post workout recovery will be slower and you'll likely be more sore. Building muscle is definitely harder without consuming complete proteins, and you simply may not have energy throughout the day to do your workouts and everyday chores.
Where Else Can You Find Protein?
Those complete and incomplete protein sources listed before are not the only foods where you can find this important macronutrient. Most foods contain protein, even fruits and vegetables, but in just very small amounts.
It's basically impossible to get your daily protein needs covered from only fruits and veggies. Even if you ate broccoli all day, which is one of the most protein-rich vegetables out there, you'd need to eat 8 cups of it to get even just 20 grams of protein…
You probably never want to eat broccoli again after this sad experiment.
To make sure that your body functions properly, you recover quickly and have enough energy throughout the day, get your protein from complete protein sources. That's the easiest option. You're missing out if you don't pay attention to getting all the essential amino acids.
If you don't eat meat or dairy products, you have to plan your meals smartly so that you put together right foods that form complete proteins.
Question: What's your favorite food or meal that is rich in complete proteins?
I’m a vegan lifter and have no problem meeting my protein requirements. I don’t spend any more time planning my meals than anybody else. I’m never sore. My endurance and recovery are very good. In fact, these are common experiences among vegan athletes. Please don’t be discouraged to try a whole foods plant based diet if it’s something you’re interested in. It’s really much easier than it seems.
Kersten Kimura says
Hi Sara! Thanks for your comment. Just generally speaking, it probably takes a little bit more planning to find good protein sources if you’re eating plant based diet. I’m glad you’ve found what works for you!
The purpose of my comment was to share my experience that, no, it doesn’t take more work to eat plant based, even though when I started I expected it to. It was just a matter of wrapping my head around it and thinking of the food groups in a different way in terms of what micro and macro nutrients they provide. The only thing I would say takes more planning is just the general notion that I won’t be hitting drive through when out and about, but that would be true of anyone with nutritional goals. (There are certainly things I can order drive through but choose not to because of my health nut leanings.)