May 2025 Issue
Great Debates: Protein Recommendations
By Carrie Dennett, MPH, RDN
Today’s Dietitian
Vol. 27 No. 5 P. 26
How much is enough, and is more really better?
With the pendulum swinging between low-fat and low-carb trends, protein had once long been the neutral macronutrient. But today, it’s developed a health halo. What began with research suggesting that we need to aim higher than the RDA for protein1 has morphed into the more extreme social media trends such as “protein girlies.” This has created a vast divide between the voices claiming that the RDA is just fine and those who suggest we pack every eating opportunity with maximum protein.
How big is that divide, exactly? The RDA for protein is 0.8 g per kg of body weight per day, but many social media and other online influencers are promoting 1 g per lb per day—or 2.2 g/kg/day—to maintain and build muscle. The dietitians interviewed for this article agreed that for most populations the RDA may be too low, but the amounts being promoted by many influencers may be too high.
For example, Angie Asche, MS, RD, CSSD, owner of Eleat Sports Nutrition in Lincoln, Nebraska, says the RDA is too low for individuals who are looking to improve their body composition and increase muscle mass. “On the other hand, not everyone needs to be having 2.2 g/kg daily.” Both Asche and Melissa Mitri, MS, RD, a nutrition writer and owner of Melissa Mitri Nutrition in Monroe, Connecticut, say the ideal amount is likely somewhere in between—Asche says 1.2 to 1.6 g/kg may be a more appropriate range—and that it’s no surprise that so many consumers and patients are confused about how much protein they need.
“Many of my clients are often confused by the varying recommendations and tend to think more protein is always better, particularly when they are very active on social media,” Mitri says. “It’s definitely a challenge that RDs have to tackle on the regular to help clients and consumers cut through the noise.”
The RDA for protein is the minimum intake to prevent inadequacies and prevent muscle loss in 97.5% of healthy adults.2 Unfortunately, it’s often communicated poorly to patients and consumers, incorrectly cited as the recommended intake rather than the required minimum intake, or phrased not as a weight-based recommendation, but as a flat recommendation of 46 g/day for women and 56 g/day for men. This is problematic.3
“That 0.8 g/kg is really just the amount that our body needs to maintain basic physiological function. So that does not include someone who has a chronic illness, who’s active, who’s regularly moving their body, who’s under a significant amount of stress, or has dietary restrictions,” says Arizona-based dietitian and strength coach Abby Chan, MS, RDN, RYT, co-owner of EVOLVE Flagstaff. “So that 0.8g/kg gets blown out of the water pretty quickly, because most of us are going to enter into one of those buckets.”
For some nutrients, intakes above the RDA are recommended to optimize specific health outcomes, and growing evidence says this practice should apply to protein as well, since the RDA doesn’t adequately capture the quantity, quality, and distribution of protein that would benefit many adults.4 “More research5 is being uncovered on the role of muscle mass in supporting immunity, metabolic rate, bone and muscle health, and longevity,” Mitri says. “Because of this, the only population where the current RDA may fit is the very sedentary population. Because they are not active, their protein needs will not be as high.”
However, Debbie Petitpain, MBA, RD, a Charleston, South Carolina-based spokesperson for the Academy of Nutrition and Dietetics (the Academy), says that she recommends sedentary adults go even higher than the RDA, to at least 1 to 1.2 g/kg. Seattle-based Angel Planells, MS, RDN, CD, FAND, also a spokesperson for the Academy, says there is one benefit to the RDA—its simplicity. “Similar to recommendations like drinking 8 cups of water per day or eating five servings of fruits and vegetables, it serves as an easy starting point,” he says.
Turning back to the influencers recommending 2.2 g/kg/day, is that much protein better, or is it just more? Petitpain notes that this recommendation is not strictly evidence based. “While it may align with some recommendations for specific groups, such as athletes or individuals pursuing aggressive body composition goals, research shows that intakes above 1.6 to 1.8g/kg generally do not provide additional benefits for muscle protein synthesis in natural trainees or nonathletes.”
Chan says that while 1 g/lb/day is easy math—which alone may be the basis for that recommendation—it’s extreme. “That even exceeds the recommendations for most athletes, whether you’re a strength-based athlete or an endurance-based athlete. That exceeds the recommendations for someone who has acute traumatic injury or is getting surgery,” she says. “Then people take that as, ‘If I don’t do this my body’s going to completely catabolize into oblivion,’ which is not true. People end up setting this huge goal, and then that automatically starts to reduce how much we’re able to get of carbohydrates and fats and other really essential nutrients in our day.”
Val Schonberg, MS, RD, CSSD, LD, MSCP, FAND, an Atlanta-based board-certified sports dietitian and certified menopause practitioner, takes a more qualitative view of protein goals. “If an otherwise healthy person who has rather reliable hunger/fullness cues is constantly eating past fullness or eating when they are not hungry to meet some external definition of what is enough, I think that’s a sign that it is too high.” Looking at the big picture of health, she also questions the impact of large doses of protein over time. “What about heart disease or the environmental effects of increasing animal protein production to meet these ‘high’ amounts?”
Optimal Amounts for Various Populations
The Acceptable Macronutrient Distribution Range for protein was established by the Institute of Medicine in 2005 and is stated as 10% to 35% of total calories or 0.8 to 2.5 g/kg/day. The RDA was derived largely from short-term studies of nitrogen balance in young adults,4 which unfortunately tend to overestimate dietary nitrogen intake and underestimate nitrogen excretion.1
“Multiple studies over the past 10 years suggest the current RDA is too low for most of the population,6 Mitri says, noting that this includes adults over 65 at a higher risk for muscle and bone loss, active individuals—not just elite athletes—and those on weight loss diets.
Older Adults
Numerous studies have demonstrated that older adults use dietary protein less efficiently and benefit from intakes above the RDA.4 For example, older adults experience a phenomenon known as anabolic resistance of skeletal muscle, which means their muscle is less sensitive to stimulus from resistance exercise or dietary protein. This can be overcome with higher volumes of resistance exercise, which may not be practical, or higher doses of protein.4 It’s worth noting that protein intakes for older adults were established in predominantly healthy people,7 yet more than 95% of older adults have at least one chronic health condition, and nearly 80% have two or more.8
“From the research I’ve looked at, it seems that 0.8 g/kg/day is insufficient to accommodate changes with aging,” Schonberg says. “But in studies where people aren’t meeting their protein needs, it’s because they are skipping meals. Around 1 g/kg/day seems to provide benefits in terms of protecting lean tissue and supporting bone and the immune system.” She points to the PROT-AGE Study Group recommendations of 1 to 1.2 g/kg/day for healthy older adults, 1.2 to 1.5 g/kg/day for those with either chronic or acute illness, and 2 g/kg/day for malnourished older adults and those with severe illnesses.9
However, while many observational studies have found an association between higher protein intake and improved physical function in older adults, others have not.10 Intervention trials looking at whether higher protein intake improves muscle mass or strength have also been inconsistent, with some showing no effect. Some of this inconsistency may be due to the relatively short duration of the studies, generally lasting six months or less,4 as well as the variability in study design.11 Some of these studies use boluses of isolated protein, such as whey or casein.12
Athletes and Physically Active Adults
For generally active people, Mitri and Chan both recommend around 1 g/kg. “In my experience, the current protein RDA is insufficient for most people to keep them full and provide the energy needed to build and maintain muscle mass,” Mitri says. For individuals who are training more intensely, Chan’s recommendations range from 1.2 to 2 g/kg. “Typically, it’s been thought that strength athletes need more protein, but I would actually wager that endurance athletes do, because they have much more muscle breakdown.”
The Academy, Dietitians of Canada, and the American College of Sports Medicine jointly recommend 1.2 to 2 g/kg/d for physically active individuals,13 while the International Society for Sports Nutrition recommends 1.4 to 2 g/kg/d for that population.14 In line with that, Asche says she recommends a range of about 1.4 to 2 g/kg/day for athletes, dependent on the type and intensity of training, while Petitpain starts a bit higher, and says 1.6 to 2 g/kg may be beneficial for strength training or endurance athletes, or adults trying to lose weight.
Weight Loss
It’s well established that weight loss results in loss of both muscle and adipose tissue. Research has found that with energy deficits of 500 to 750 kcal/day, protein intakes of 1.6 g/kg/day help preserve muscle mass.15 Asche says while she recommends at least 1.2 g/kg, for individuals seeking weight loss, she says ideally that amount is closer to 2 g/kg, depending on activity level. “We know that protein has a higher thermic effect of food compared to fat and carbohydrates and helps us maintain lean muscle tissue while in a calorie deficit.”
Mitri says for weight loss, she typically recommends between 1.2 to 1.6 g/kg.16 “For a woman in perimenopause and menopause who is active, I may recommend on the higher end of this range, closer to 1.5 to 1.6g/kg, to reduce muscle breakdown often occurring in this stage of life. For someone younger and less active, I may suggest the lower end of this range.”
Schonberg says she’s not convinced that people in menopause, or who are middle-aged and older, need to eat more protein than other adults. “In many cases, I see these numbers causing women especially to overeat and contributing to unnecessary weight gain. In my experience, I’ve found that rigid rules about how much someone needs to eat of anything have proven unhelpful and potentially harmful.” Instead, she suggests gentle guidance about what a ‘balanced meal’ might look like and helping clients plan meals that include an enjoyable source of protein at each of three to four meals a day.
Protein Quality: The Leucine Question
The dietary requirement for protein is a surrogate for the amino acids that make up protein. There has been much discussion about the importance of leucine, thought to be the main amino acid that stimulates muscle protein synthesis (MPS).4 “Consuming adequate leucine is important for building muscle, and the amount you need increases as you age,” Petitpain says. “Current thought is you may need as much as 3 g of leucine at one time to stimulate MPS, although resistance training lowers this threshold.” That corresponds to approximately 25 to 30 g protein/meal.
There’s been a move to replace animal protein with plant protein for both human health and environmental health, but, as Petitpain points out, the amount of leucine in protein foods varies, with animal proteins generally containing higher amounts of leucine than plant-based sources. That’s contributed to a belief by some experts and influencers that plant protein is inferior.
However, the leucine hypothesis originated with animal and in vitro studies, and a 2024 review challenged that hypothesis, noting that current research is driving a more nuanced picture that brings into question the extent to which leucine alone can explain or predict the magnitude of the postprandial MPS response. The authors say that while leucine may still be an important factor and could indeed turn out to be the single most important factor, it’s clear that humans’ physiological response to dietary protein is more complex.17
“A vegetarian should be mindful of their leucine intake if muscle loss prevention is a goal, but they need not be overly concerned if they plan their diet appropriately,” Petitpain says. “Eating mixed meals or consuming a supplement fortified with leucine can help.” She notes that some plant proteins, such as soy and pea powder, have a relatively higher leucine content, and other higher leucine foods include pumpkin seeds, hemp seeds, lentils, black beans, peanuts, and almonds.
A 2022 review noted that plant proteins may have some limitations for MPS, primarily low essential amino acid and leucine contents, lower protein bioavailability, and lower protein content per serving. However, the authors found these limitations may be overcome by combining different food groups throughout the day to ensure an adequate intake of all amino acids and leucine, using preparation and cooking techniques that increase the bioavailability of plant proteins, and increasing the serving sizes of plant foods or isolated plant proteins.18
Chan says she’s concerned by some of the plant-based/vegan rhetoric claiming that we only need 50 g of protein per day. “They’re not looking at activity levels, they’re not looking at an aging population. They’re not even basing it on the size of your body,” she says. “Yes, I think some individuals may focus way too much on protein, but especially in the plant-based realm, we need to look at the quality of protein that’s coming in. Are you getting adequate amino acids? If not, then we probably need to be focusing on that and including a little bit more protein there.”
Protein Thresholds and Optimal Timing
Many research studies have found that distributing protein evenly across meals—rather than having, say, a breakfast with 10 g of protein and a dinner with 60 g of protein—is important for optimizing MPS.19 Planells says while consuming adequate protein each day is important for MPS, discussions about protein quantity “often lead to misconceptions such as, ‘if some protein is good, more must be better,’ or a hyper-focus on specific components like leucine as the sole driver of muscle growth. However, as Ben Franklin said, ‘If you fail to plan, you’re planning to fail.’ Proper planning and distribution of protein intake are essential to achieve optimal results.”
Researchers have observed that MPS is activated about 30 minutes after consuming protein foods containing about 3 g of leucine and remains elevated for about 2.5 hours—and that adding more protein to a meal does not increase the magnitude or duration of this anabolic period.20,21 However, these studies tend to use fast-digesting proteins, such as whey, whereas slower-digesting casein, for example, can prolong the anabolic response for at least 12 hours,20 and physical activity near the meal can both increase and lengthen the body’s response.21
Also, most studies test the anabolic response at breakfast after fasting all night. Limited evidence suggests that the response to protein is lower later in the day, perhaps making breakfast the crucial meal. Notably, in studies that observe greater 24-hour MPS with an even protein distribution, protein is closer to 30% of calories at breakfast, instead of 10%.20
A 2020 review said although the effect of protein distribution can’t be adequately disentangled from the effect of protein quantity, following a more balanced protein distribution through the day may be a practical way for adults with marginal or inadequate protein intakes to achieve a moderately higher total intake. However, for adults already consuming at least the RDA, the study said most evidence supports that consuming at least one meal that contains sufficient protein quantity to maximally stimulate MPS is sufficient.22
Another rationale for spreading balanced protein intake throughout the day is the idea that we have a per-meal protein absorption threshold. “Conventional wisdom recommended an upper threshold of 20 to 25 g of protein per meal. This was based on the thought that any more than this would be oxidized and therefore would not provide any additional MPS benefits,” Mitri says. “However, new research is emerging that challenges this idea, suggesting while a higher amount may result in more amino acid oxidation, a good percentage of the amino acids are still utilized for muscle-building purposes.”
This research argues that studies recommending a maximum of 20 to 25 g/meal tend to use fast-digesting proteins such as isolated whey protein, and consumption of slower-acting protein sources, especially when consumed in combination with other macronutrients, would delay absorption and thus could enhance amino acid utilization. The authors found that to maximize anabolism, a better target is 0.4 g/kg/meal across a minimum of four meals in order to reach a minimum of 1.6 g/kg/day if the primary goal is to build muscle.23
But subsequent research suggests that target could be even higher. A 2020 crossover study fed eight healthy older adults isocaloric mixed meals containing 35 g and 70 g of protein from lean ground beef, with one week in between. The higher protein meal stimulated greater MPS and a higher full-body anabolic response.24 Not to be outdone, a 2023 study demonstrated that consuming 100 g of milk protein resulted in a greater and more prolonged anabolic response following a bout of resistance-type exercise, compared to the ingestion of 25 g of protein, negating the need for balanced protein distribution through the day.25
Schonberg says while this study is interesting, it brings up a lot of questions. “What would happen with a different source of protein? Over time, does the body adapt, thus spreading protein throughout the day would still be more beneficial? Does a large bolus of protein ingested at one meal translate into strength gains? That study showed that excess amino acids weren’t oxidized, or wasted, as protein scientists have believed, but the important question is over time how does it translate into muscle quality vs. just mass?”
Chan says this newer research “allows us to kind of step away from that rule that if you don’t get protein in right now, there are going to be problems. Granted, I would say that if you’re trying to consume 80 or 100 g of protein in one meal at one time that’s probably not going to feel good.” She noted that there are many other reasons to eat protein throughout the day, including satiety.
Mitri says in her weight loss practice, she recommends evenly spacing protein intake throughout the day to promote satiety. “So rather than getting a large amount of protein at dinner and very little at breakfast, I suggest a more even split such as 25 to 30 g per meal and 10 to 15 g per snack, if needed, to meet their daily needs.” She notes that we need more research to determine if there is an optimal upper threshold, or if this threshold may vary depending on the individual. “Until we have these specifics, the bottom line is ensuring clients receive enough protein to meet their needs by the end of the day.”
Final Food for Thought
What factors should RDs consider when determining protein recommendations? “There’s a lot of information coming from both reputable and lay sources which is confusing, even to me,” Petitpain says. “You have to check your sources and avoid recommendations that demonize certain foods or promote extreme intake recommendations based on personal experience rather than science.” She also suggests looking at whether there’s a financial incentive for someone to push protein intake. For example, if the recommendation “requires” using a particular supplement or product.
Schoenberg says it can be more helpful, and less confusing, to focus on food rather than numbers. “So, instead of eating 30 g of protein, someone would eat a bowl of chili that has ground turkey, beef, or chicken, with beans and a bunch of vegetables,” she says. “Eating ‘more’ protein at the expense of other nutrients is not helpful messaging. I think it contributes to more food rules and promotes fear and worry that something bad will happen if you aren’t reaching a certain target.”
Schoenberg and Chan both note that calories matter, too. “We can’t just eat protein,” Chan says. “Protein’s health halo makes many people assume protein can do no wrong and eating protein means we automatically build more muscle. “It doesn’t work like that. We must give it a job for that to happen.”
— Carrie Dennett, MPH, RDN, is the nutrition columnist for The Seattle Times, owner of Nutrition By Carrie, and author of Healthy for Your Life: A Non-Diet Approach to Optimal Well-Being.
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