The Science of Protein and Its Role in Longevity, Cancer, Aging, and Building Muscle

welcome to today's deep exploration into one of nutrition's most critical and debated topics protein Beyond its well-known role as the building block of muscle protein is fundamental to our metabolism insulin sensitivity and the prevention of diseases such as type two diabetes and sarcopenia but how much dietary protein do we really need and could too much protein especially from meat actually be harmful today we'll discuss why maintaining and even building muscle is critical for everyone not just athletes you'll discover how protein intake coupled with resistance training drives muscle repair and growth enhancing athletic performance improving metabolic health and promoting longevity by acting as a defense against age related Frailty you'll learn about optimal protein amounts based on age activity level and goals whether you want to actively gain muscle maintain it or just improve body composition we will critically examine current protein recommendations challenging the adequacy of the RDA of 0. 8 G per kilogram body weight drawing on the latest research we discuss why higher intakes ranging from 1. 2 to 1.

6 grams per kilogram are more beneficial for General Health and why up to two grams or higher may be best for body recomposition addressing the contentious links between high protein diets and health risks we will analyze evidence surrounding proteins association with cancer heart disease and kidney function we'll explore how lifestyle factors particularly physical activity profoundly influence these risks specifically we'll uncover how exercise modulates growth factors like igf-1 diverting them towards muscle and brain tissue where they support repair and growth while potentially mitigating their procancer effects in other tissues we dissect the differences between animal and plant proteins in stimulating muscle protein synthesis we'll provide practical strategies for vegetarians and vegans to meet their protein needs effectively through increased total intake Diversified sources and the use of plant-based protein concentrates we'll also dispel myths around protein intake timing you'll learn how Distributing protein evenly across males can maximize muscle protein synthesis and why the so-called post exercise anabolic window may not be as narrow as once thought additionally we highlight the pivotal role of the amino acid Lucine in activating muscle building Pathways and how this impacts protein quality considerations by the end of this episode you'll be equipped with all of the evidence-based insights you need to better navigate common misconceptions and ultimately harness protein for muscle maintenance performance and a Frailty free future so let's get into it how much muscle we have tells us more about how we are aging than body weight or BMI ever could here's a startling fact after the age of 50 the average person loses about 1% of their muscle mass every single year and it's not just muscle mass strength plummets even faster dropping around 3% annually by the time you reach 75 if you're not engaging in regular strength training you could be losing up to 4% of your strength every year so what can we do about this exercise both before you need it building muscle Reserve but also in old age to slow and reverse the decline while resistance training is the most important factor for building and maintaining muscle mass and strength protein intake plays an important role too a metaanalysis from DrStuart Phillips and colleagues highlights the importance of protein intake by showing that people who engage in resistance training and supplemented with additional protein taking their total daily protein intake up to 1. 6 gram per kilogram body weight increase their muscle mass by 27% and their strength by 10% more than those who did resistance training without additional protein supplementation so these people were getting around 1. 2 g of protein per kilogram body weight so dialing in that protein intake matters for both muscle mass and strength when combined with resistance training skeletal muscle makes up around 30 to 40% of our lean body mass more muscle doesn't just mean more strength it means better metabolism enhanced insulin sensitivity and a pretty good defense against type two diabetes it also dramatically decreases Frailty and the risk for sarcopenia one of the the main risk factors for Falls and fractures in older adults research has shown that individuals who suffer from a fragility fracture are twice as likely to die compared to those without such fractures and between 22 to 58% of people with a hip fracture pass away within just 12 months after the injury in old age falling and breaking a hip can literally be a death sentence a better body composition dramatically improves quality of life and reduces disability risk having a higher muscle mass can decrease the risk of early death by 30% whereas having a high fat Mass can increase that risk by 56% so what explains our greater susceptibility to lose muscle mass as we get older there are a few factors that play a role in this but a big player here is a phenomenon called anabolic resistance so as we age our muscles become less responsive to amino acids meaning they don't trigger muscle protein synthesis in response to protein intake as effectively so for older individuals the same amount of protein results in a smaller increase in muscle protein synthesis compared to younger people some Studies have shown that an older person requires almost twice as much protein for the same response for example around 0.

24 gram of protein per kilogram body weight or 0. 1 G per pound that's 20 gram of protein for about an 80 kgam man maximally stimulates muscle protein synthesis in someone young but this dose is higher for older adults who need about 0. 4 gram of protein per kilogram or 0.

18 gam per pound of protein per dose an older adult man weighing about 80 kilg would need about 32 grams of protein to maximally stimulate muscle protein synthesis by the way for anyone taking notes this suggests that the optimal amount of protein per dose is between 20 and as high as 35 gram of protein depending on your personal level of anabolic resistance so this means a few things the first is that if you're older you need a higher total daily protein intake to maintain or increase muscle mass it also means that you need a higher dose of protein at each meal to stimulate muscle protein synthesis but anabolic resistance is not inevitable or only due to aging as some might suggest in fact physical inactivity may actually be the biggest contributor reducing physical activity worsens anabolic resistance for example taking fewer steps for just 2 weeks causes anabolic resistance in older adults and reduces their insulin sensitivity imagine what decades of inactivity can do that's the bad news but the good news is that exercise makes muscle more sensitive to protein and essentially negates anabolic resistance when older adults exercise before protein intake their muscle anabolic response is identical to that of a younger adult so how do I interpret this active old older adults probably don't experience as much anabolic resistance as inactive people and therefore it might not be such an issue for people that are Physically Active the most effective way to combat anabolic resistance as we age is through regular physical activity combined with a higher daily protein intake ideally around 1. 6 gram per kilogram body weight we do not have to be frail in old age we can build muscle into our 40s 50s 60s and even our 70s and Beyond and we can def Ely increased muscle strength and power output at this age in one study that recruited adults aged 90 years and older 8 weeks of high-intensity strength training produced a 174% increase in muscle strength muscle strength and size increased even in the ninth decade of Life an age when most people wouldn't even think twice about touching a weight so let's talk about the optimal protein intake the optimal amount of protein will not be the same for everyone some people want to build muscle mass some people want to Main ttain it and others want to improve their body composition by building muscle and losing fat each of these goals requires a more tailored approach the first thing to knowe is that it's generally agreed upon that protein needs should be calculated based on a lean body mass or an adjusted body weight reflecting a healthy body fat percentage so for example 12 to 15% for men and around 20% for women this prevents unrealistic targets especially for those who are overweight or obese so when I refer to protein intake in grams per kilogram of body weight per day what I'm ideally referring to is your ideal or goal body weight let's address one thing up front the recommended dietary allowance or the RDA for protein of 0. 8 gr per kilogram per day is thought by many to be too low this is because the RDA was derived from nitrogen balance studies which have limitations due to incomplete collection and inaccurate estimates of amino acid loss the optimal range for daily protein intake is closer to 1.

2 to 1. 6 G per kilogram body weight per day or roughly 0. 54 to 0.

72 G per pound this is based on alternative methods like stable isotope studies which consistently show that higher intakes are necessary to maintain a positive protein balance far above the 0. 8 G per kilogram often cited so aiming for at least 1. 2 gr and up to 1.

6 G is what we're talking about for optimal protein intake there's good evidence to suggest this for example older adults consuming at least 1. 2 grams of protein per kilogram body weight per day prevented age related losses in lean mass when compared to consuming the RDA of 0. 8 gr per kilogram body weight older women were also 30% less likely to experience Frailty when consuming protein above the RDA so what is the optimal protein intake for building muscle while resistance training for people engaged in resistance training a protein intake of 1.

6 gram per kilogram body weight per day has been shown to maximize gains in lean body mass with a 27% increase in muscle mass over even a 1. 2 gam per kilogram intake that's a lot and it really just serves to really underscore how low the RDA really is when you're talking about 0. 8 G per kilogram body weight by the way for an excellent discussion of the protein RDA and much more see my interview with DrStuart Phillips in episode 76 of the Fami Fitness podcast there are special circumstances where even a higher protein intake might offer some marginal benefit the first example is people undergoing body recomposition where they are in an energy deficit to lose fat Mass while preserving or even increasing muscle mass so let's talk a little bit more about body recomposition and weight loss a higher protein intake tends to improve satiety it helps you feel Fuller for longer and may help prevent overeating for people who want to lose weight this is a major benefit eating more protein is also essential during weight loss to prevent the loss of lean body mass when you eat a higher protein calorie restricted diet more weight loss comes from fat mass than muscle mass but remember resistance training is also important to prevent the loss of lean mass high protein diets may also cause a slight increase in the metabolic rate due to the thermic effective food helping you burn a few more calories throughout the day the second example where a higher protein intake above 1.

6 G per kilogram may be beneficial is with professional athletes where extremely marginal improvements in muscle protein synthesis gives them an edge on competition so in this scenario this is where up to 2. 2 grams of protein per kilogram per day or one gram per pound May provide marginal benefits despite common misconceptions a very high protein intake is not harmful to Kidney Health in people without pre-existing kidney conditions research consistently shows that high protein diets are safe for most people and any concerns over kidney damage are largely unfounded so let's talk about this myth early interpretations of certain studies suggested that excessive protein intake might overwork the kidneys while protein restriction can slow the progression of kidney disease in some individuals we now know this does not imply that a healthy people should limit their protein consumption higher protein diets do induce changes in kidney function but they do not overburden the kidneys The observed increase in markers in kidney function is a normal adaptive response to eliminate Ura and other waste products generated during protein metabolism this is entirely normal for individuals with healthy renal function so current evidence does not support an association between higher protein intake and kidney disease among healthy adults or those at risk such as individuals with obesity hypertension or even diabetes I abetes moreover research and athletes has shown that consuming protein intakes as high as 3. 2 to 4.

5 Gams per kilogram of body weight per day for up to one year does not cause any adverse changes in kidney function and is considered safe this intake is four to six times higher than the RDA for protein and emerging research even suggests that higher protein intake may actually be beneficial for people with chronic kidney disease some Studies have found that consuming protein at levels above the RDA is associated with reduced mortality risk in this population challenging the traditional approach of protein restriction the bottom line we can finally put to rest the myth that high protein diets harm healthy kidneys it's time to tackle another important aspect of protein intake and that's how often and when we should consume it we'll tackle two key points first how we consume our daily protein intake whether we should spread it evenly across 3 to four meals or load it up into one or two meals second and related does protein have to be consumed within a critical anabolic window or timed with our workouts in short the answer to both of these is that factors are less important overall than you might expect emerging evidence reveals that the body can effectively utilize even very large protein doses this challenges the notion that protein must be meticulously spread over multiple meals to maximize muscle protein synthesis even though an even daily protein distri distribution is ideal this doesn't mean that consuming the same total amount of protein in fewer high protein meals is ineffective protein distribution is important but not vital when you eat a larger dose of protein it takes longer to digest but your body will eventually use it this is contrary to what some people think happens when you consume more than 20 to 25 grams of protein in a single meal they think that the excess protein will just be excreted by the body and otherwise wasted in fact fact a study by DrLuke Van Lon and colleagues found that consuming 100 grams of protein after exercise led to a more robust and prolonged anabolic response than did 25 grams of protein but had negligible effects on amino acid oxidation the conclusion from this study was quote the magnitude and duration of the anabolic response to protein has no upper limit in humans and has been severely underestimated end quote this dispels a few myths about how the body can use only 20 to 25 gram of protein at once as a practical takeaway a more evenly distributed pattern of protein intake throughout the day is probably what we should be striving for but evidence like this highlights why more and more experts seem to be aligning on the simple fact that the vast majority of us athletes or not should be thinking about protein intake from the standpoint of total daily intake with less overall focus on factors like timing or the per meal intake another question that people have regarding protein timing is whether protein needs to be consumed immediately after exercise to enhance the effects of training this idea is known as the anabolic window the anabolic window is a period after exercise typically lasting from 30 minutes to 2 hours during which the body is primed to absorb and utilize nutrients particularly protein and carbohydrates for muscle repair and growth it occurs because the body's ability to synthesize protein and replenish glycogen stores is heightened aided by exercise induced hormonal changes like increased insulin levels consuming 20 to 40 grams of high quality protein often paired with carbohydrates can enhance Muscle Recovery and growth during the anabolic window or so it was once thought recent scientific evidence reveals that muscle protein synthesis remains significantly elevated for a full 24 hours following exercise effectively debunking the notion of a very narrow anabolic window lasting only a few hours furthermore supplementing with protein before exercise has the same effects on body composition and strength compared to supplementing with protein immediately after exercise in other words there are no meaningful differences between pre and post exercise protein ingestion this means that you're free to choose when you want to consume protein in relation to exercise so long as your total daily intake of protein is adequately High to support optimal muscle protein synthesis of course there is definitely no downside to consuming protein immediately after a workout especially for people interested in achieving marginal gains in strength or muscle mass to wrap up our discussion on protein timing and distribution I want to bring up one more strategy to help with muscle building that relates to protein distribution and timing pre-sleep protein there's two ways to look at this one way is through the lens of Tim restricted eating and the other is through the lens of actively optimizing for muscle protein synthesis on training days it's been shown in Studies by DrLuke Van Lun and colleagues that protein consume before bed is digested and absorbed overnight it also increases overnight muscle protein synthesis rates and improves net protein balance in people who had performed resistance training earlier in the day to enhance Muscle Recovery the benefits of pre-sleep protein have also been shown during chronic resistance exercise training consuming about 30 grams of protein before bed every night while resistance training appears to increase muscle mass and muscle strength another thing about pre-sleep protein is that it does not seem to reduce appetite or diminish the muscle protein synthesis response at breakfast the next morning which may have been a concern for some people overall I think pre-sleep protein is just one way to increase total daily protein intake if you don't like going to bed hungry having a low calorie protein shake on training days may have the benefit of potentially enhancing your muscle gain on those training days but don't use this as an excuse to go wild we should still be mindful about the fall and insulin sensitivity that happens as we get close to our habitual bedtime and this is particularly true if you're not actively training so let's summarize some key points about protein timing and distribution first while it's not necessary to consume protein immediately after a workout there's no harm in doing so for those who exercise fasted having a protein Rich meal right after may be beneficial ultimately total daily protein intake is the most crucial Factor second evenly Distributing protein across meals is ideal but your body can use even large protein meals and finally consuming protein before bed isn't essential but it can be a helpful strategy to boost total daily intake or support Muscle Recovery especially in those who are actively training all this talk about protein lacks context unless we discuss the best sources of protein particularly when it comes to stimulating muscle protein synthesis is animal protein better than plant protein what about whey protein compared to casine protein a highquality protein can be efficiently digested and utilized to maximize muscle protein synthesis several factors influence a protein's digestibility including whether it's a whole food source an animal-based or plant-based protein Source the presence of other nutrients like fiber which are mainly present in plant foods and the amino acid composition of the protein when it comes to the amino acid composition Lucine is of particular importance for protein quality the main anabolic component of protein is the branch chain amino acid Lucine which is a potent stimulator of muscle protein synthesis Lucine stimulates muscle protein synthesis by activating the mtor pathway which is our body's Central regulator of cell growth and Metabolism in fact Lucine appears to be more critical than the total protein content of food or supplement in determining the muscle protein anabolic response this concept is referred to as the loosen threshold or the Lucine trigger hypothesis which suggests that a specific amount of Lucine must be consumed to activate muscle protein synthesis essentially Lucine acts as a switch kickstarting the muscle protein building process about 0. 25 grams of protein per kilogram body weight in a single meal provides a saturating dose of Lucine and amino acids to stimulate muscle protein synthesis for up to 6 hours that's about 2 to three grams of Lucine which can be obtained by consuming 20 G of a high quality protein like whey protein even though Lucine might be the most important amino acid for stimulating muscle protein synthesis all of the amino acids are required to allow the process of muscle protein synthesis to sustain for 4 to 6 hours loosing is the signal but we also need to have all of the building blocks to build and repair muscle protein exercise lowers that loosing threshold because it makes muscle more sensitive to amino acids this means a lower dose of Lucine and therefore a lower dose of protein is needed to reach the Lucine threshold and stimulate muscle protein synthesis after exercise aging does reduce the sensitivity of lucing and other amino acids it takes a larger dose of protein or Lucine to stimulate the same muscle protein synthesis response for someone who is older compared to a younger adult but again older adults who routinely exercise can help overcome this since exercise increases sensitivity Lucine if you're consuming a variety of plant-based and animal-based food sources and or supplementing with whey protein you probably don't have to worry about consuming enough Lucine at each meal or throughout the day focusing on Whole Foods is the best way to ensure you're getting enough Lucine but of course if you're concerned adding whey protein or Branch chain amino acid supplement to your diet is another way to get additional Lucine now let's talk about the difference between protein from animal and plant-based sources animal versus plant prot protein whether your loyalties are towards a plant-based diet or a meat inclusive diet from a standpoint of just focusing on optimizing for muscle protein synthesis an animal Source protein is better it is also easier for most people to obtain protein from an animal-based food source for a few reason for one animal protein sources have a greater protein density plant-based foods contain less protein per gram than most animal based foods for example getting 20 gram of protein from potatoes means you need to consume more than a kilog of potatoes but just 70 gram of meat like chicken or beef contain 20 gram of protein second plant-based foods have a lower digestability than animal-based Foods largely due to the presence of a food Matrix consisting of fiber fiber can slightly reduce the body's ability to extract and utilize protein found in plants it also slows the digestion process sprouting and fermenting can overcome some of this and improve the digestibility and absorption of plant protein third plant proteins are often deficient in one or more of the essential amino acids for example lysine methionine and most importantly Lucine remember that essential amino acids are needed to be consumed in the diet to build complete proteins in the body a lower essential amino acid content means that most plant proteins are incomplete proteins and stimulate a lower anabolic response compared to animal-based protein if you're eating plant-based you do have options protein needs can be met on plant-based diets by supplementing with plant-based protein isolates and concentrates by consuming a larger quantity of protein each day to compensate for a lower protein quality and also by diversifying the intake of a variety of plant-based sources of protein so creating complimentary proteins that have the right amino acid profile despite the lower anabolic potential of plant-based protein sources studies generally support the idea that as long as the total daily protein intake is high enough a vegetarian or a vegan diet can support daily muscle protein synthesis and gains in muscle size and strength as much as a diet containing animal-based protein but because plant protein is lower in quality you'll have to consume more food overall to reach your daily protein intake but Whole Foods aren't the only source of protein many people choose to obtain their protein through protein supplements or protein powder and there's a good reason to think that this is a fairly sensible practice whey protein is one of the most popular protein supplements in part because it's an extremely high quality protein Source whey is a rich source of the essential amino acids cysteine and the branch chain amino acids Lucine isol leucine and veiling Whey also contains several bioactive peptides the loosing content of whey is what makes it stand out the loosing content in way is 50 to 75% higher than other protein sources compared to the other component of milk protein like casin whey protein is more rapidly digested and stimulates muscle protein synthesis more effectively at r and after exercise making it a go-to protein source for many athletes the slower digestion of casine compared to whe isn't necessarily A downside because this means casine provides a prolonged release of amino acids that can be helpful for sustaining the muscle protein synthesis response for a longer period of time whey and caseine protein are both much higher quality protein sources than collagen which has a lower quality amino acid profile it's rich in Glycine and Proline but lacks essential amino acids like Lucine furthermore collagen does not significantly enhance muscle protein synthesis or muscle connective protein synthesis at rest or after exercise making it a suboptimal protein choice for those engaged in resistance training and wanting to improve skeletal muscle protein synthesis it should be clear from our discussion thus far that dietary protein especially when optimized to suit your individual goals and needs has an array of health benefits for nearly everyone it's performance enhancing anti-aging from the standpoint of Frailty prevention and can help you lose weight however this might come as a surprise to many but there is a school of thought within the Aging community that too much dietary protein increases cancer risk and contributes to accelerated aging yet today many athletes consume a high protein diet and the fact of the matter is being an athlete even a recreational one is one of the best things we can do to age well this is both intuitively and scientifically obvious how do we reconcile these facts let's get into it some researchers argue that a high high protein intake especially for meat accelerates aging and even raises the risk of cancer and early death this idea stems largely from laboratory studies showing that restricting protein intake extends lifespan in animals and observational data linking High animal protein diets to a higher mortality rate supporting this idea one study found that middle-aged adults consuming high protein diets where 20% of their calories came from protein were 75% more likely to die from any cause and four times more likely to die from cancer this is a pretty shocking statistic and animal evidence corroborates some of this at the mechanistic level however there is more to this story in another major study middle-aged adults consuming high protein diets did show increased mortality rates but only if they had other unhealthy lifestyle factors like obesity smoking heavy drinking or being sedentary among healthy people this Association disappeared so does a High animal protein diet really pose a health risk or is it more about what unhealthy lifestyle factors exist in someone's life this is where it gets interesting protein particularly from animal sources spikes levels of a hormone called igf-1 which can help build muscle support brain health it enhances muscle repair but high igf-1 levels also come with potential downsides like promoting the survival of pre-cancerous cells and potentially allowing them to form cancer numerous Studies have found an association between elevated igf-1 levels and an increased risk of various cancers so should we cut protein drastically to lower igf-1 levels not necessarily lowering igf-1 too much can come with its own set of risks for example calorie restriction which significantly drops igf-1 has been linked to brain matter loss in non-human primates this raises questions about whether low igf-1 might have trade-offs in terms of brain health so is it better to significantly cut protein intake and avoid these risks or is there a balance to be struck that gives us the best of both worlds muscle strength muscle repair cognitive health and protection against cancer a recent meta analysis by Drwter Longo and colleagues highlighted this idea showing a U-shaped relationship between igf-1 levels and mortality both very high and very low igf-1 were linked to higher death rates what was the optimal range it was actually around 120 to 160 nanog per milliliter and to reach this igf-1 sweet spot researchers estimated a daily protein intake of around 50 to 80 gam which is not very much protein not to mention this study did not specifically look at healthy Physically Active people and that's a critical piece to the puzzle because a strong response to exercise requires igf-1 so it raises a philosophical question are these recommendations aimed at healthy Physically Active individuals or are they tailored to people maintaining a largely sedentary lifestyle physical activity fundamentally changes how igf-1 behaves in the body exercise lowers igf-1 in the bloodstream redirecting it to where it can be beneficial like the muscle and notably the brain here's why that's important when you exercise whether it's cardiovascular exercise or strength training or high-intensity interval training it stimulates muscle fibers and increases igf-1 receptor density in the muscle cells this makes muscle tissue more sensitive to igf-1 potentially enhancing its uptake while this precise mechanism is still being explored in research what's clear is that exercise increases the ability of igf-1 to cross the bloodb brain barrier once in the brain igf-1 plays a crucial role in promoting neurogenesis that's the growth of new brain cells especially in regions of the brain like the hypoc campus which is important for learning and memory exercise doesn't stop there exercise particularly intensive exercise also raises levels of proteins that bind to igf-1 and reduce its bioavailability to damage cells that could potentially form cancer cells exercise alone causes more amino acids to be taken up into skeletal muscle which also has the effect of reducing circulating igf-1 in fact when protein is consumed after exercise igf-1 levels do not increase in the ensuing 24 hours like they do when protein is eaten with without exercising beforehand so by channeling how igf-1 is used and making it less available to potentially stimulate cancer cells exercise acts as a protective shield regular physical activity has long been shown to strongly reduce the risk of many types of cancer and this may just be one crucial mechanism that accounts for that fact furthermore exercise enhances the immune system's ability to find and destroy cancer cells it lowers chronic inflammation which is a known risk factor for cancer and it improves insulin sensitivity which can further influence igf-1 levels so in short higher igf-1 levels aren't inherently dangerous it's the context that matters exercise and a healthy lifestyle change the story entirely showing us that igf-1 can be a powerful Ally for health strength and also longevity when Guided by an active balanced lifestyle this brings us to another important question if protein truly is inherently pro-aging wouldn't we expect a population with a higher protein intake athletes for example to experience reduced life expectancy but this doesn't appear to be the case and in fact the opposite is true athletes who we can reasonably expect generally consume higher protein amounts and are known to have elevated igf-1 levels consistently show longer lifespans and a better health metric on average they live 2 to eight years longer than the general population they also die less of cancer and cardiovascular diseases let's Circle back to the amino acid Lucine whether we're talking about optimizing muscle protein synthesis or controversies in the Aging field surrounding igf-1 and mtor Lucine is at the heart of it Lucine is the critical signal driving robust activation of mtor animal protein has a lot of lucing and whether you consider that a good thing or not actually depends on your views of igf-1 and mtor mtor plays key roles in skeletal muscle growth by driving muscle protein synthesis and recovery but this brings us to another area where mtor pathway has also sparked controversy it's potential connection to atherosclerosis a study from early 2024 suggested that a high protein intake could accelerate the development of atherosclerosis which is the hardening and stiffening of arteries the study suggested that Lucine which activates mtor and muscle tissue to drive muscle growth might also activate mtor in the vascular system promoting plaque buildup through immune Cell Activation the important thing to remember is that exercise causes Lucine to be taken up by muscle where it activates mtor in muscle to build and repair muscle rather than spending time in the bloodstream triggering mtor in the vascular system this is yet another example of how being physically active versus sedentary changes the entire equation it's a different game for people who exercise regularly okay so I hope it's clear by now that the evidence suggesting high protein diets are harmful to health is not particularly strong when it comes to some observational data suggesting a potential link between high protein intake and risk like cancer this risk primarily applies to sedentary individuals with other unhealthy lifestyle factors like obesity for physically active people it's a different story exercise ensures that protein and Lucine are directed toward muscle growth and repair keeping mtor activation where it's beneficial in the muscles rather than in peripheral tissues this explains why athletes despite consuming more protein enjoy Better Health and longer lifespans than the general population the bottom line is that for active individuals higher protein intake supports performance longevity and health all right everyone that just about does it for our discussion on the science of protein to wrap up I want to provide eight of the most important takeaways number one for most adults a protein intake in the range of 1. 2 to 1.

6 G per kilogram of body weight per day should be consumed to to support overall health older adults athletes and people who want to lose weight while sustaining lean body mass should consume 1.