I’ve honestly never seen such a love for a macronutrient in my life.
On one hand, it’s great – protein helps keep us fuller for longer, and as someone who lived through the carb-heavy 90’s, I’m super happy to see people adding more balance to their meals.
On the other hand, protein adds a major health halo to some products that we might want to rethink.
Like, do we really need chips made out of egg whites or collagen protein oats? Collagen is most often sourced from animal tendons and skins. Happy eating!
Anyhow, I’ve gotten a ton of requests for a post about how much protein we need each day, and I totally understand why. It can be tough to figure out how much protein you need each day, especially with so much conflicting information out there.
Note: I don’t cover the protein needs of athletes in this post.
What is protein?
First, a brief lesson on what protein is.
Protein as we consume it, is made up of amino acids. There are 20 amino acids (in alphabetical order):
- Alanine
- Arginine
- Asparagine
- Aspartic Acid
- Cysteine
- Glutamic acid
- Glutamine
- Glycine
- Histidine
- Isoleucine
- Leucine
- Lysine
- Methionine
- Phenylalanine
- Proline
- Serine
- Threonine
- Tryptophan
- Tyrosine
- Valine
Out of those 20, 9 are essential, meaning that we must get them from food. The other 11 can be synthesized by the human body.
The essential amino acids are:
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Some amino acids might be recognizable to you. For example, proline is what collagen is made from. Melatonin is made from tryptophan. Glutamine is sometimes sold as a ‘gut healing’ nutrient.
A healthy diet has all 20 amino acids in it, and most people will get that just by eating a variety of foods. No need to count amino acids.
When we eat protein – whether it’s a chicken breast, some tofu, or in a protein shake, the amino acids are coiled into chains in the shape of helixes. These helixes are uncoiled in the stomach during digestion, and the chains make up that protein are broken up into smaller chains by enzymes in the stomach.
These chains are further broken up into individual amino acids in the small intestine, by enzymes called proteases.
The amino acids travel in the bloodstream to the liver, which synthesizes them into new chains, and shuttles them to where the body needs them.
Animal proteins are complete proteins, meaning they have all of the essential amino acids.
Plant proteins, with the exception of a few like soy, are usually low in at least one of the essential aminos.
We used to think that we needed to combine plant protein foods to make a complete protein, but we now know that this is unnecessary. If you eat a wide variety of foods daily, our bodies will combine those proteins for us.
Now that you’ve gotten your science lesson for today, here’s more of what you need to know about protein:
What is protein is used for?
We need protein to build and maintain muscles, to make immunoglobulins, enzymes, messaging proteins, transport of various molecules, and for cell structure. Protein is involved in basically every bodily process.
Protein also helps us feel fuller for longer, by releasing GLP-1 (glucagon-like peptide 1) and CCK (cholecystokinin), both hormones that play a role in satiety. Protein also decreases levels of a hormone called neuropeptide Y, which can increase hunger.
So that’s why you feel fuller when you have eggs for breakfast, versus toast with jam.
If you don’t get enough protein, you could experience a loss of muscle mass and increased risk of infections, among other things. Thankfully, most of us get more than enough in our diets.
How much protein do we need in a day?
When I was in nutrition school, we learned that most people should have around 0.8-1.0 grams of protein per kilogram of body weight. The FDA hasn’t changed that recommendation, although there’s plenty of controversy around it, because the science around protein has evolved.
Protein requirements depend on numerous factors including body composition, activity level, weight, and pregnancy.
A 2010 study done in a metabolic ward using three different protein levels in sedentary adults found that 1.4-1.8 grams per kilogram of body weight was sort of the sweet spot for protein intake.
Meaning, lower protein intake resulted in lean mass loss, and protein intake over 1.8 grams per kilogram didn’t make much of a difference in body composition.
This 2019 study on protein confirms that for optimal health, we should consider changing the RDA for protein to 1.2-2.0 grams per kilogram per day.
For a 150lb person (68 kg), using 1.4 grams of protein per kilogram, equals 95 grams of protein per day.
This 2018 review of studies by two sources I trust recommends 0.4 grams of protein per kilogram per meal, which works out to around 20-30 grams, but also recommends this four times a day. Even if you eat only three meals a day, you can make up the rest of your protein needs in snacks.
Using only our lean body mass, otherwise known as muscle, may be a more accurate way to determine protein needs. Around 1.5 grams of protein per kg/lean body mass appears to be recommended, although knowing what your LBM is is tough if you don’t have access to bioelectrical impedance or another tool that can determine it. Most people can just use total body weight for the calculation below.
What I recommend for most healthy people is a protein intake of around 1.2-1.4 grams per kilogram, per day.
This is just a guideline, and remember: not every day needs to have the exact same protein/food/nutrients. It’s what we eat over time, not day to day, that matters.
In other words, please don’t obsess over every gram of protein – or grams of anything – that you eat. If you balance your meals most of the time, it all evens out.
Protein spacing.
I always recommend (as I do in my book, Good Food, Bad Diet) that each meal of the day has around 20-25 grams of protein. Build your meals by prioritizing proteins, then adding vegetables.
How much protein is in food? Here’s the amounts in some common ones:
Historically, breakfast has been the lowest-protein meal of the day (because cereal) and dinner, the highest (meat and potatoes). We know now that spacing your protein intake out roughly equally over the day has the greatest benefit for satiety and for absorption.
We need to eat protein throughout the day, because unlike carbs, which are stored in the liver and muscles as glycogen, and fat, which is stored in the body as triglycerides, the body can’t store protein for quick use. When we consume protein, the body uses what it can, then the rest is excreted or stored as fat.
To keep the supply flowing, you should be eating protein consistently.
Does protein turn into fat?
As far as protein being turned into fat, this can happen, but physiologically, it may only happen if we far overshoot our caloric needs with protein.
This 2015 metabolic chamber study shows that overfeeding with protein may actually increase energy expenditure (more on that below), but this study didn’t measure weight. This 2017 review of studies suggests that protein overfeeding results in muscle growth, with or without an increase in fat mass.
Long story short: it seems as though eating excess protein may result in more muscle growth and nitrogen (the byproduct of protein metabolism) excretion, but not as much an increase in fat mass.
Remember though that in real life (not in a lab for a study) that protein is usually eaten with other macronutrients, most often fat. You don’t just eat a steak, that steak has protein AND fat.
Optimal timing for post-workout protein shake? What about amino acid drinks?
We used to believe that the ‘anabolic window’ was 1-2 hours. We now understand that it’s up to 5-6 hours, based on this 2013 study. The window concept remains controversial.
So make sure you eat a meal or protein-rich snack sometime after your workout; no need to guzzle a protein drink after a standard spin class.
As far as Branched Chain Amino Acid (BCAA) drinks during a workout, you probably don’t need them if you’re eating animal protein at meals.
Angie Asche RD, owner of Eleat Nutrition and author of the upcoming book Fuel Your Body, tells me that only a very small number of people really need BCAA supplements – we’re talking marathoners and other athletes. The rest of us can get them in food.
She says, “while BCAAs may benefit performance, this does not necessarily mean that you need to be supplementing. There is little evidence to show that BCAAs provide additional benefit to performance in individuals who are consuming adequate protein in their diet.”
Can you eat too much protein?
More isn’t always better, especially when it comes to nutrition.
Studies show that eating over 1.8 grams of protein per kilogram doesn’t have an increased benefit over a 1.4 gram per kilogram amount.
Excess protein hasn’t been shown to cause damage to healthy kidneys, or to cause bone loss, both big myths about protein that have been around forever.
Does protein increase our metabolism?
The thermic effect (calories the body uses to metabolize a food) of protein is higher than both carbohydrate and fat. If you eat 100 calories of protein, you’ll use around 30 of those calories metabolizing it. 100 calories of carbohydrate, you’ll use 10 calories, and fat, 5 calories.
In that way, yes – protein does increase the metabolism, but this doesn’t mean you should be eating a diet of pure protein.
For more on metabolism, read my metabolism post here.
Are plant proteins absorbed as well as animal proteins?
To determine quality of a protein, we need to consider how many amino acids the protein contains, and how much of that protein is actually digested, absorbed, and used by the body. There are two measures of protein digestibility- the PDCAAS (Protein Digestibility-Corrected Amino Acid Score) and the DIAAS (Digestible Indispensable Amino Acid Score), both of which have their limitations.
As you can see if this amazing infographic from examine.com, plant sources of protein have a lower digestibility – and therefore are used less efficiently – than animal sources. According to this article, plant-based protein powders have a similar digestibility to animal proteins.
Digestibility of various plant- and animal-based proteins
https://examine.com/guides/protein-intake/#optimal-daily-protein-intake-for-vegetarians-and-vegans
Although plant proteins tend to have lower digestibility, this small 2021 study showed that vegans and omnivores that were both fed the same amount of protein during a resistance training program had the same amount of muscle mass growth. My recommendation? Eat the protein you enjoy.
What’s the best protein powder?
I personally think that choosing a protein powder should be based on both taste and quality. Choose the one you like, and that has the least amount of sugar in it.
In terms of quality, whey protein is the gold standard for digestibility. But if you can’t tolerate it, any other protein powder will do.
Some vegan protein powders are low in some of the essential amino acids, but if your sole source of dietary protein is NOT protein powder, which I hope it’s not, then honestly, your diet will fill these gaps.
It’s important to get enough protein in your diet, but rest assured that you’re probably doing that without having to count grams and ounces. Eat a variety of food, and make sure you spread your protein throughout the day for optimal usage and satiety.