|Nutrition trends are ever-changing, but at this point, there are some truths nearly everyone can agree upon: Refined carbs and sugar should be limited, veggies and fruit can and should be eaten liberally for their fibre and micronutrients, fats from quality sources definitely have a place in your diet, and protein is key for curbing hunger and maintaining a healthy body composition.
But of all these truths, there’s still a surprising amount of confusion about protein – especially how much you should be eating (spoiler: maybe a bit more than you think); the best food sources (steak is not a requirement); and what it can do for your health even if you don’t care that much about muscle.
“Most of us think of protein in the context of building muscle, but it also plays a key role in maintaining and repairing cells, the production of antibodies needed for immune function, and creating hormones and neurotransmitters,” says registered dietitian Abby Cannon, R.D. It’s also particularly important when you’re trying to lose weight.
All of which is to say: You can’t afford to overlook protein – even if the rise in diets like keto has you thinking all about increasing fats and slashing carbs and not much else. Here, we dive into the latest research, recommendations, and lesser-known facts about protein from functional dietitians, some of the top protein researchers in the country. Get ready, nutrition nerds, you’re in for a ride.
Protein Has Unique Properties That Increase Lean Muscle, Aid Weight Loss and Boost Mood
Protein is one of three macronutrients (the others being fats and carbohydrates) that provide energy for our bodies. When we consume protein-rich foods like seafood, eggs, and legumes, we break their protein down into its individual amino acids, which our bodies then utilise to perform countless functions, including building our own muscle (via muscle protein synthesis).
Additionally, researchers are finding that prioritising protein seems to be quite important for losing fat and keeping it off while preserving muscle, slowing the ageing process, reducing risk factors for type 2 diabetes and cardiovascular disease, and even offsetting some of the damage of a sedentary lifestyle.
Here are some of the most compelling science-backed benefits and lesser-known facts about this multitasking macro:
1. Your Body Burns Calories Simply By Digesting Protein
Whenever we eat something, our bodies expend a certain amount of energy (i.e. burn a certain amount of calories) just by breaking them down and digesting them. This is known as the thermic effect of food, or dietary-induced thermogenesis. Turns out, protein has the highest thermic effect of all the macronutrients because it takes more energy to break it down into its individual amino acids and then build those back up into amino acid chains in your body.
“With fat and carbs, about 5% of their calories get burned through thermogenesis, while about 15% of protein gets burned through thermogenesis,” says Donald Layman, Ph.D., a professor emeritus of nutrition at the University of Illinois (although some studies say it may be a bit higher). “It means you can eat about 100 more calories a day if it’s coming from protein than if it’s coming from carbs, so it’s not insignificant.”
Alone, experts don’t think protein’s thermic effect is enough to trigger any significant weight loss. But it’s definitely one piece of the puzzle that makes protein-rich foods weight-loss-friendly, and some research suggests it’s part of the reason protein is so dang satiating.
2. Protein Is The Most Satiating Macronutrient, Which Can Help You Lose Weight
“There’s pretty good agreement that protein has a higher satiety value, and nobody really knows why for sure,” says Layman. Basically, this means protein has been found to keep you fuller and more satisfied than consuming an equal amount of carbs or fat.
This satiating effect is likely due to a combination of factors, including protein’s thermic effect, mentioned above. According to a recent research review on protein and weight management, when you experience greater diet-induced thermogenesis, your body is expending more energy and increasing its oxygen consumption. And, oddly enough, researchers say this ‘oxygen deprivation’ may translate into feelings of satiety.
Additionally, “studies show that eating a higher protein meal (compared to a higher carbohydrate meal) stimulates the secretion of a number of satiety hormones like PYY and GLP-1,” says Heather Leidy, Ph.D., an associate professor of nutrition at the University of Texas at Austin who studies protein’s effects on weight and satiety. “These hormones are associated with increased feelings of fullness and satiety and have been shown to decrease subsequent food intake. Post-meal improvements in glycemic control [blood sugar control] have also been reported with higher vs. normal protein diets.”
All of this suggests that replacing some refined carbs with protein-rich foods can be super beneficial.
But this absolutely does not mean you should skimp on vegetables, fruit, and other fibre-rich, whole-food carbs. “I think the quantity of the protein in combination with what other foods are included within the meal are critical factors,” says Leidy. “Specifically, there seems to be a synergistic effect with eating foods rich in protein and fibre for satiety.”
3. Protein Helps Build Metabolically Active Lean Muscle, Making It Easier To Maintain Weight Loss
As you know by now, increased protein consumption also stimulates protein synthesis, which helps build and preserve lean body mass. And the more lean mass you have, the more calories you naturally burn at rest.
4. Protein Can Help Offset Muscle Loss Associated With A Sedentary Lifestyle
While you may think it’s important to focus on protein intake only if you’re working out all the time, this couldn’t be further from the truth. Even if you’re a desk jockey, getting your fill of protein has big benefits.
During bed-rest studies, middle-aged people can lose up to 2 pounds of muscle just from their legs in seven days,” says Douglas Paddon-Jones, Ph.D., professor of nutrition and metabolism at the University of Texas Medical Branch.
“But some of the pretty new research coming out suggests that if we give additional protein, we can partially protect this muscle mass. This extends to people who live a sedentary lifestyle.”
Being sedentary also impairs your body’s ability to use blood glucose, says Paddon-Jones, so if you add more protein-rich foods in place of unhealthy carbs, that’s even better.
5. Protein Can Boost Functionality And Quality Of Life As You Age
“Adequate protein as you age can also help prevent sarcopenia, a condition characterised by the loss of skeletal muscle mass and function that can drastically reduce quality of life and even lead to premature death. “Sarcopenia is sort of like osteoporosis but for muscles,” explains Paddon-Jones. “It starts to appear in your 40s, but it’s a subtle insidious loss of muscle, less than 1% per year. So if you’re not quite getting your protein requirements, you’re not going to notice this slow, gradual reduction; it sneaks up on you.”
6. Protein Is A Key Dietary Component For Managing Anxiety And Mood
Amino acids act as a major building block for almost every biological process in the body. For instance, “amino acids are the building blocks of neurotransmitters such as dopamine and serotonin,” says Miller. “For this reason, those deficient in protein are also deficient in neurotransmitters that can drive hunger and cravings leading to weight gain and can even impact mood, anxiety, and sleep.”
Many experts believe anxiety is also partially driven by imbalanced blood sugar. So, ensuring you get enough protein in your diet (along with healthy fats and plenty of fibre) can offset some of these anxiety-inducing spikes and dips.
7. Replacing Carbs With Protein May Reduce Risk Factors For CVD And Diabetes
Recent articles also illustrate improvements in type 2 diabetes and cardiovascular disease risk factors with the daily consumption of increased dietary protein.
A new study found that by making a moderate macronutrient shift by substituting carbohydrates with protein and fat for six weeks, patients with type 2 diabetes experienced a reduction in HbA1c levels (higher levels are associated with diabetes) and liver fat content.
Another recent study found that high-protein, low-carb diets were more effective for losing weight and keeping it off than low-calorie diets among obese individuals, suggesting that they’re a sustainable dietary strategy for reducing cardiovascular disease risk.
So, how much protein should you eat to reap the benefits? First, let’s be clear: Your specific protein needs will vary depending on a bunch of factors like age, body weight, body composition goals, physical activity levels, and whether or not you’re pregnant.
Your needs will also somewhat depend on the quality of the protein you’re eating (more on that later). But one thing that all of the protein researchers we spoke with agreed on was that most people will benefit from eating more than the RDA for protein, which is 0.8 grams per kilogram of body weight per day (or 0.36 grams per pound body weight). Think of the RDA for protein as a minimum, not an optimal goal.
You’ve undoubtedly read articles stating that most Americans meet the RDA and therefore get “more than enough” protein. But, researchers say, these claims are at least somewhat flawed in that they misconstrue what RDA actually means.
“The RDA is defined as the minimum amount of protein to prevent a deficiency, and it does that,” says Layman. “People who get the RDA don’t show any visible signs of deficiency, but it’s not the same as being ideal for preventing things like risk of diabetes or obesity, or muscle wasting and sarcopenia for older adults, especially as we become more sedentary.”
This, of course, raises the question: If you’re aiming for optimal health and not just covering your bases, what’s a good protein range to strive for? ”
Most of the data says you want to be consuming 1½ to 2 times the RDA,” says Layman. “The RDA is 0.8 g/kg, so we think the ideal range is between 1.2 and 1.6 g/kg.”
Layman isn’t alone in this thinking: “From a weight management perspective, eating nearly twice the RDA has been shown to be beneficial,” says Leidy, who coauthored a 2016 paper stating that protein intake in the 1.2 to 1.6 g/kg range is a more ideal target for adults, helping promote healthy ageing, appetite regulation, weight management, and athletic performance goals.
This range holds true even if you’re not very active, as recent research (mentioned above) has shown adequate protein intake helps stave off muscle loss even in sedentary individuals.
But what do nutrition experts outside of the protein field think? According to Miller, “The RDA is likely ample to support biological and structural need for weight maintenance. However, when looking for weight loss goals, it would be important to consider an increase of 1 to 1.4 g/kg to ensure muscle sparing and maintain an active metabolic rate.” Cannon somewhat agrees but adds that even though the RDA doesn’t necessarily represent how much we should eat every day, it’s still a good baseline number.
If you’re an athlete – or you work your body hard every day – you may need to go higher, but even then, you shouldn’t exceed 2 g/kg without consulting a registered dietitian, says Nancy Rodriguez, R.D., Ph.D., nutritional sciences professor and director of the sports nutrition program at the University of Connecticut.
It’s not that this amount of protein is going to cause you harm (research has largely dispelled the long-held beliefs that eating protein above your needs causes bone loss or kidney problems, unless you already have kidney disease), but it may end up stored as fat if your increased protein intake pushes you beyond your caloric needs.
What do these recommendations look like in real life?
Let’s use a 150-pound (68-kg) person as an example. Depending on their specific goals and health status, they would likely opt to consume 0.8, 1.2, or 1.6 grams of protein per kilogram of body weight. Here’s what their daily protein quota would be in each of those scenarios:
• 0.8 g/kg: 54 grams of protein per day
• 1.2 g/kg: 75 grams of protein per day
• 1.6 g/kg: 105 grams of protein per day
Pro tip: To calculate your protein intake based on the g/kg model, first convert your weight to kilograms (your weight in pounds ÷ 2.2) and then multiply that by the g/kg recommendation that makes sense for your lifestyle.
How you spread out your protein in a day is key.
Further, it turns out, it’s not exactly optimal to simply figure out your protein needs and then cram it in whenever. To reap the most benefit in terms of satiety, blood sugar balance, and muscle protein synthesis, you want to spread out your protein over the course of the day.
Your best bet: Aim to get around 20 to 30 grams of protein per meal to maximize the benefits. “Thirty grams of protein at a meal are what we think it takes to trigger maximum muscle protein synthesis and maximum thermogenic effect for the least amount of calories,” says Layman.
Consuming more than that amount in one sitting may be counterproductive.
A groundbreaking 2009 study found that people consuming 90 grams of protein at one meal experienced the same benefit as eating 30 grams. “Both turned on muscle protein synthesis the same,” says Paddon-Jones, who was the study author. “Your ability to consume, digest, and then use the amino acids in the protein is really limited to three to four hours surrounding the meal. So even if you eat an entire chicken at breakfast, those amino acids aren’t available at dinner,” he says.
What if you don’t eat according to a traditional three-meal-a-day schedule? That’s fine, but at least try to consume 25 to 30 grams of protein on two separate eating occasions (and more via snacks, if necessary), suggests Layman.
Also, make your first meal of the day, whether that happens in the morning or noon, protein-rich. A 2015 study authored by Leidy found that people who ate about 30 grams of protein at breakfast for 12 weeks experienced a reduction in daily hunger, naturally consumed fewer calories, and did not gain fat compared to people eating 13 grams of protein (the typical American gets just 10 grams at breakfast).
How Intermittent Fasting, Keto, And Other Dietary Strategies Affect Your Protein Needs
Something you may find surprising: If you’re reducing your calorie intake with something like a time-restricted eating form of intermittent fasting (think 16:8 fasting, where you eat all your food within an eight-hour window), that doesn’t mean your protein intake should go down proportionally – unless you were eating too much protein to begin with.
“Unlike fat and carbs, the recommendation for protein is more of an absolute number,” says Layman. “It’s grams per kilogram of body weight. So even if you eat less calories, you still need the same protein,” says Layman. Paddon-Jones agrees: “You still have to hit that gram amount per meal to maintain lean mass.” And remember, that lean muscle mass helps you burn more calories, even while you’re at rest.
Maintaining adequate protein on keto is also crucial. Miller says people may not be eating enough protein when they shift to a low-carb, high-fat keto diet.
“If you’re following a classic ketogenic diet, which was developed more for epilepsy and neurological disease management, it’s often too protein-restricted,” says Miller. “What happens, often with women, is that their appetite is regulated and they don’t have organic hunger. So they undereat—and they under-eat protein pretty dramatically.” This, in turn, can lead to symptoms like fatigue, brain fog, and even hair loss.
All of this might have you wondering: How do more intense fasting plans (think a day or longer) affect your ability to maintain muscle mass? Most of the experts we spoke with said there’s just not enough research to be sure. While, in theory, it makes sense that going a day or longer without protein would cause a decrease in muscle protein synthesis and an increase in muscle breakdown, “there seem to be some muscle-sparing effects that come into play,” says Miller.
But, the extent to which these muscle-sparing effects would be able to offset muscle breakdown over the long term isn’t clear.
“I think a 25- or 30-year-old might be just fine, but I would never recommend fasting for a 55- or 60-year-old,” says Layman. “The older you get, any muscle loss tends to be permanent, but a younger person tends to recover pretty quickly.”
Are all protein-containing foods created equal? No, and here’s why.
In the nutritional science world, researchers tend to describe protein as ‘high quality’ or ‘low quality.’ A high-quality protein would be a food that contains a high proportion of all the essential amino acids. There are 20 total amino acids used by the body, nine of which are essential (meaning we need to obtain them from food), and all nine have to be present in a food or a meal to trigger muscle protein synthesis.
Nearly all animal-based protein sources, such as yogurt, cheese, meats, fish, and eggs contain all nine essential amino acids and thus are considered high quality. Most plant-based sources of protein, on the other hand, don’t contain a high proportion of all essential amino acids, which makes them incomplete, and, at least in this particular sense, ‘low quality.’
There’s an exception, though. “The highest quality non-animal protein is still soy,” says Rodriguez. “It has all of the essentials and an amino acid profile that’s more similar to what you’d see in dairy, eggs, or meat.”
Animal-based proteins also tend to contain more protein for fewer carbohydrates and calories. For example, you can get about 25 grams of protein in 3 ounces of meat, but you’d need to eat almost 3 cups of black beans to hit that number, says Rodriguez.
Selecting The Best Animal-Based Protein Sources
Even though animal-based protein is considered ‘high quality’ in the nutritional science world, loading up on grilled chicken breast isn’t necessarily your best bet – there’s a different type of ‘quality’ you should also consider, particularly when it comes to meat.
“Proteins in their whole-food form with the fewest parts removed are going to be the most balancing for the body. For instance, consuming a bone-in, skin-on, pasture-raised chicken thigh will provide more of the amino acids glycine and proline, found in an animal’s connective tissue, than just eating the muscle meat,” says Miller. “The whole-food delivery aids in balancing out amino acids in the body and preventing dominance of the amino acid methionine, which is prevalent in muscle tissue and can drive more inflammatory processes in the body. So overall, taking a snout-to-tail approach to animal consumption provides the most nutrient density and supports a more sustainable model of meat consumption.”
Nutritional researcher and wellness entrepreneur Chris Masterjohn, Ph.D., expresses a similar sentiment on his website, stating that excessive methionine actually depletes glycine, and another good approach to balance these amino acids is to add a serving of collagen powder or bone broth to your daily diet. “Collagen, found abundantly in the skin, bones, and other connective tissue of animals, provides 25 times as much glycine as methionine,” he says.
And there are even more reasons to love grass-fed collagen. While it’s not a complete protein (it doesn’t contain the essential amino acid tryptophan, the precursor to serotonin), grass-fed collagen does have unique therapeutic properties in its own right that make it a worthy addition to smoothies, soups, oatmeal, and baked goods. “The medical literature on collagen is significant, with research supporting its ability to help minimize cellulite, alleviate joint pain and inflammation, strengthen nails and hair, and maintain gut lining integrity,” says Miller. “I make sure I get 2 grams of collagen per day as a sort of insurance policy.”
Other animal-based proteins to consider that are both high quality and sustainable to consider adding to your diet include:
• pasture-raised eggs and poultry
• grass-fed, grass-finished meat
• sustainable wild-caught fish
• grass-fed dairy and whey protein
Selecting The Best Plant-Based Protein Sources
To be clear, no one’s actually bashing plant protein, even though it’s received the whole ‘low-quality’ designation in certain circles. “There are so many good reasons to adopt a more plant-based diet, but if you exclude all animal-based proteins and you’re not smart about how you plan your plant-based diet, you can run into problems really quickly,” says Paddon-Jones.
So on a vegan diet, combining a variety of protein-rich, plant-based foods is key, as they ‘complement’ one another to give you the full spectrum of essential amino acids your body needs.
Some experts say you simply need to consume a variety of plant-based proteins over the course of a day to get this benefit, but others don’t believe this is very efficient, including Paddon-Jones. “The smarter, more pragmatic approach is to combine different protein sources at each meal,” he says. “It just makes sense on so many levels, not just for protein but for diversifying overall nutrient intake.”
Also important to note is that the protein in plant foods is a bit less bioavailable than protein from animal foods due to the structure of the plant itself, such as the presence of phytates in legumes, which interfere with protein absorption, says Miller.
“If you’re choosing to stay vegan, some of the best proteins are soaked and sprouted legumes and lentils; and you should consider a plant protein powder blend including pea protein and hemp seed.”
Cannon, who personally follows a plant-based diet, recommends incorporating some of the following protein-rich plant foods into your diet as well – whether you’re vegan or not:
• legumes (chickpeas, lentils, and beans—kidney, black, adzuki, butter, pinto, fava beans)
• whole soy (organic, non-GMO tofu, tempeh, edamame beans)
• nuts (almonds, Brazil nuts, cashews, pecans, walnuts)
• seeds (sunflower, pumpkin, flax, chia, sesame)
• whole grains (brown rice, quinoa, millet, farro, wild rice)
• a plant-protein blend, ideally free of added sugars
If you’re concerned you’re not getting enough protein on your plant-based diet, consult with a registered dietitian.
Also, Layman recommends bumping up your resistance training: “Because maintaining a healthy proportion of lean muscle mass is a result of both consuming dietary protein and exercising, if you’re committed to doing a lot of resistance exercise, you can actually get away with a little less protein,” he says.
We get it; this is a lot to take in. Probably more than you ever wanted to know about protein, right? But what it essentially comes down to is this:
The amino acids in protein perform countless functions within the body that boost both physical and mental health and help you reach or maintain a healthy weight without feeling deprived—particularly when they replace unhealthy carbs and are eaten alongside good fats and plenty of fibre. And while many people are hitting their baseline protein intake with the RDA, the current research suggests most people could benefit from eating more protein (from the animal- and plant-based options listed above) and by dividing that protein among two or three separate meals.
But just remember, like any other food or nutrient, protein in isolation isn’t a miracle cure for anything—and loading up on it while disregarding other aspects of your diet, or to the point that you exceed your caloric needs, could be counterproductive.