HoldsUp

Luc van Loon

Luc van Loon is a researcher in the fields of exercise science, sports nutrition, and muscle metabolism. His published research focuses on dietary protein requirements, muscle protein synthesis rates, and the metabolic effects of exercise. He also investigates the impacts of amino acid supplementation and resistance training on muscle mass and recovery across diverse populations, including athletes, older adults, and clinical patients.

55 claims checked on air: 2 context 1 contradicted 4 overstated 41 supported 7 unverified

What they said on air - supported

13 citing their own research

0:01:31supportedhightheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Skeletal muscle protein turns over at a rate of 1% to 2% per day, renewing completely in approximately 50 to 100 days.

"And so for muscle, that happens at a rate of 1 to 2% per day, which means that in, say, 50 to 100 days, you have completely renewed your muscle." (said at 0:01:31)

Human metabolic tracer studies measuring muscle protein synthesis (MPS) and fractional synthetic rate (FSR) consistently show that skeletal muscle protein turns over at approximately 1.0% to 2.0% per day under normal conditions (typically ~1.2% to 1.6%/day in healthy young and older adults). At an average fractional replacement rate of 1% to 2% daily, the theoretical complete turnover of muscle protein occurs across approximately 50 to 100 days, although individual sub-fractions (e.g., mitochondrial, myofibrillar, and sarcoplasmic proteins) turn over at slightly varying rates.

0:03:03supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Historical nitrogen balance studies showed that most people maintain neutral balance at 0.66 g protein/kg/day, leading to the 0.8 g/kg/day dietary recommendation.

"And if you actually give a low-protein diet, you go down to .66, then most people actually stay in a neutral balance. And then they suggested, with some leverage on top, we actually get to the .8 grams." (said at 0:03:03)

The claim accurately describes how dietary protein recommendations were derived from historical nitrogen balance studies. A meta-analysis of nitrogen balance studies by Rand et al. (2003) determined the median Estimated Average Requirement (EAR)—the level at which 50% of healthy adults maintain neutral nitrogen balance—to be 0.65 to 0.66 g protein/kg/day (105 mg N/kg/day). Adding statistical variance (2 standard deviations or the 97.5th percentile) to cover virtually all healthy adults yielded the Recommended Dietary Allowance (RDA) of 0.80 to 0.83 g protein/kg/day (132 mg N/kg/day).

0:11:14supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Muscle protein synthesis increases after both endurance-type exercise and resistance-type exercise.

"the muscle protein synthesis goes up after exercise when you do endurance-type exercise, but also when you do resistance-type exercise." (said at 0:11:14)

The claim is fully supported. Extensive human metabolic research using stable isotope tracer techniques demonstrates that acute bouts of both resistance exercise and endurance exercise stimulate skeletal muscle protein synthesis (MPS). While the specific subfraction of proteins synthesized varies by modality and training status (with resistance training preferentially stimulating myofibrillar protein synthesis and endurance training preferentially stimulating mitochondrial protein synthesis), both modes increase overall muscle protein synthesis after exercise.

0:16:26supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Exercise in the absence of food intake increases both muscle protein synthesis and muscle protein breakdown, but increases synthesis to a greater extent than breakdown, improving net muscle protein balance.

"exercise increases muscle protein synthesis, also increases muscle protein breakdown, but it increases muscle synthesis to a greater extent than it increases muscle breakdown, so net balance becomes better. That's without food intake." (said at 0:16:26)

Stable-isotope tracer studies in humans demonstrate that resistance exercise in the fasted state stimulates both muscle protein synthesis (MPS) and muscle protein breakdown (MPB). Because MPS increases to a significantly greater magnitude than MPB (e.g., MPS increasing by ~112% at 3 hours post-exercise compared to a ~31% increase in MPB), net muscle protein balance improves (becomes less negative/more positive) compared to resting fasted conditions, even in the absence of food intake.

0:20:02supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

In healthy young adults, ingesting 20 grams of high-quality protein maximally stimulates muscle protein synthesis over 4 to 6 hours, with 40 grams providing no further increase.

"if you give young healthy people about 20 grams of a high-quality protein, you see a maximum stimulation of muscle protein synthesis. Giving 40 grams did not result in a greater muscle protein synthesis. We'll talk about the 100 grams later on, probably. But so in the in the next 4 to 6 hours after a meal, 20 grams maximizes muscle protein synthesis." (said at 0:20:02)

Classic dose-response randomized trials in healthy young adults show that ingestion of approximately 20 grams of high-quality protein (such as egg or whey protein) reaches a plateau in stimulating muscle protein synthesis over a 4-hour postprandial window, with 40 grams producing no statistically significant further increase while increasing rates of amino acid oxidation and ureagenesis.

0:21:03supportedmoderateDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Performing an exercise session prior to food intake restores the postprandial muscle protein synthesis response in older adults to an almost completely normal level.

"Now, if you provide if you give an older person an exercise session before food intake, their response is almost completely normal." (said at 0:21:03)

A primary hallmark of aging skeletal muscle is anabolic resistance, characterized by a blunted muscle protein synthesis (MPS) response following meal or protein ingestion compared to younger individuals. Clinical trials utilizing stable isotope tracer infusions and muscle biopsies demonstrate that performing an acute bout of exercise (either resistance or aerobic exercise) prior to protein or amino acid feeding significantly enhances nutrient delivery, amino acid uptake, and postprandial MPS rates in older adults, effectively restoring anabolic responsiveness.

0:21:03supportedmoderateDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Michael Rennie's research group was the first to define the concept of anabolic resistance.

"Mike Rennie's group was the first to define that as anabolic resistance." (said at 0:21:03)

Michael J. Rennie's research group formally coined and defined the concept of 'anabolic resistance' to describe the blunted muscle protein synthetic and metabolic response to anabolic stimuli—such as amino acid feeding, hyperinsulinemia, and exercise—in contexts such as aging, muscle disuse/immobilization, and critical illness.

0:27:43supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

The initial gains in strength during the first several weeks of resistance training are predominantly driven by neuromuscular adaptations rather than muscle hypertrophy.

"The gain in strength is the first step. The body tries to uh generate more strength with the the stuff that it has, and most of that is neuromuscular. And then when the body constantly is being driven to do more than it wants, then it starts thinking like, "Okay, now it maybe becomes more efficient to build some extra muscle."" (said at 0:27:43)

A well-established tenet of exercise physiology is that early strength gains during the initial weeks of resistance training are primarily mediated by neuromuscular adaptations (such as increased neural drive, enhanced motor unit recruitment, changes in motor unit firing rates, and reduced antagonist co-activation) before significant muscle hypertrophy occurs.

0:28:15supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

During aging, the loss of muscle strength is greater than can be explained solely by the loss of muscle mass.

"I mean when we become older we lose more strength than can be explained by the amount of muscle that we have lost, so there's also a neuromuscular component." (said at 0:28:15)

The speaker's claim is well supported by neuromuscular and aging physiology literature. Longitudinal and comparative studies consistently demonstrate that age-related loss of muscle strength (dynapenia) outpaces the loss of muscle mass (sarcopenia), indicating that muscle mass decline only partially accounts for strength reduction. Neurological and motor unit factors—such as decreased corticospinal excitability, reduced voluntary neural activation, and changes in contractile properties—explain a major portion of age-related muscle weakness.

0:33:43supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Dose-response studies in healthy young individuals show that 20 grams of protein maximizes muscle protein synthesis at rest or post-exercise, with 40 grams showing no greater response over a 4 to 6 hour window.

"there's basically two dose-response studies that show in healthy young people, um at rest or after exercise, 20 grams maximizes muscle protein synthesis for somewhere between uh 4 to 6 hours after the meal. So in that time period, 4 to 6 hour postprandial period we call that, some of that protein might not have been digested and absorbed if you give more than those 20 grams. So the 40 grams that they showed in those studies didn't show a greater response, but they only measured for 4 or 6 hours, depending." (said at 0:33:43)

Two landmark randomized dose-response trials in healthy young individuals (Moore et al., 2009 and Witard et al., 2014) evaluated the effects of graded protein doses (0 to 40 g of egg or whey protein) on muscle protein synthesis (MPS) over a 4-hour postprandial period at rest and after resistance exercise. Both trials demonstrated that myofibrillar and mixed muscle protein synthesis rates plateaued at 20 g of protein, with 40 g showing no statistically significant additional stimulation and instead leading to increased rates of amino acid oxidation and ureagenesis.

0:34:10supportedmoderatetheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Ingesting 100 grams of protein prolongs digestion and absorption and induces a greater muscle protein synthesis response when measured over 12 to 24 hours compared to smaller doses.

"Now we wanted to do a study to show that if you give 100 grams, which is absolutely not something that I'm suggesting that people should be consuming, that it takes longer to digest everything and that you have a longer stimulation of muscle protein synthesis over a more prolonged period of time. So we also measured not over 6 hours, but over 12 and even 24 hours, and then we see that you get a greater response." (said at 0:34:10)

A randomized trial by Trommelen and colleagues (PMID 38118410) investigated the metabolic fate and muscle protein synthesis response to consuming a 100 g bolus of milk protein versus a 25 g bolus or placebo (0 g) during post-exercise recovery over a 12-hour period using quadruple stable isotope tracers. Ingestion of 100 g of protein resulted in prolonged amino acid digestion and absorption (persisting for over 12 hours) and induced a significantly greater and more sustained postprandial myofibrillar and muscle protein synthesis response compared to the 25 g dose.

0:39:02supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Administering 40 grams of protein in the evening or during sleep is digested, absorbed, and stimulates muscle protein synthesis overnight.

"they showed that if you give um 40 grams of protein in the evening, that protein is digested and absorbed while you sleep because we use that intrinsically labeled protein so we could follow it, and it's actually converted to muscle." (said at 0:39:02)

Randomized controlled trials using intrinsically stable isotope-labeled proteins (such as intrinsically 13C-phenylalanine-labeled casein) demonstrate that 40 grams of protein ingested before sleep is effectively digested and absorbed overnight, increasing circulating amino acid availability and stimulating overnight muscle protein synthesis rates in both young and older adults.

0:41:40supportedmoderatetheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

A deuterated water study showed no difference in muscle protein synthesis or fat loss between time-restricted eating and non-time-restricted eating.

"we've done a study, a more longer-term study, Imre did that with labeled water, and she did that when um in in Melbourne, where I had a visiting professorship position there, and we didn't see a difference in muscle protein synthesis with the time-restricted eating versus the the non-time-restricted eating... The other thing on on that study was we didn't see differences, or that project I should say, is we didn't see a difference in fat loss." (said at 0:41:40)

The speaker accurately describes a 10-day randomized controlled trial led by Dr. Imre Kouw using deuterated water (D2O) to track muscle protein synthesis (MyoPS) during time-restricted eating (an 8-hour eating window) versus an extended eating control (a 12-hour eating window) in males with overweight or obesity. The study found no statistically significant difference in daily integrated myofibrillar protein synthesis rates (1.28% vs. 1.26% per day) or overall body mass changes between groups.

0:46:20supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Individuals can gain muscle mass with a daily protein intake of 0.8 grams per kilogram of body weight when engaging in resistance training.

"there's even studies that um so, again, um 0.8 g of protein, you can actually gain muscle on 0.8 g of protein. Maybe you can gain more muscle on 1.2, but you can still gain muscle on a 0.8 g protein per kilogram body mass per day." (said at 0:46:20)

Published randomized controlled trials and systematic reviews demonstrate that resistance exercise is the primary driver of skeletal muscle hypertrophy and that individuals consuming the Recommended Dietary Allowance (RDA) of protein (~0.8 g/kg/day) can still achieve significant increases in muscle mass and fat-free mass. Meta-analyses show that while higher protein intakes (up to approximately 1.6 g/kg/day) can optimize and augment resistance training-induced muscle gains, consuming 0.8 g/kg/day does not prevent muscle hypertrophy from occurring.

0:46:48supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Performing exercise with a specific limb directs a greater proportion of ingested dietary amino acids into that exercised muscle compared to non-exercised muscle.

"If you actually do exercise and we ingest the same protein that we can tract throughout the body, we see that the same amount of protein is, of course, digested and absorbed, but more goes to the leg that did exercise." (said at 0:46:48)

Human clinical trials using intrinsically labeled dietary proteins (such as casein labeled with L-[1-13C]-phenylalanine and L-[1-13C]-leucine) combined with continuous intravenous stable isotope infusions confirm this claim. Studies demonstrate that while dietary protein digestion and systemic amino acid absorption remain comparable, performing exercise prior to protein ingestion significantly augments postprandial muscle protein synthesis and increases the direct incorporation of ingested dietary amino acids into de novo myofibrillar and connective tissue protein in the exercised muscle compared to non-exercised resting conditions.

0:48:21supportedmoderateDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Resistance exercise sensitizes skeletal muscle to the stimulation of muscle protein synthesis by food intake for up to 24 to 48 hours.

"exercise makes the muscle more sensitive to the stimulation of muscle protein synthesis through food intake, but it does so for up to 24 to even 48 hours. So if you do an exercise session today, your response to breakfast tomorrow morning will be greater, but also lunch tomorrow afternoon and also dinner tomorrow night." (said at 0:48:21)

Human metabolic tracer studies demonstrate that a bout of resistance exercise sensitizes skeletal muscle to subsequent protein intake, enhancing the myofibrillar protein synthetic response to feeding for at least 24 to 48 hours compared to feeding at rest. For example, Burd et al. (2011) showed that the stimulation of myofibrillar protein synthesis in response to 15 g of ingested whey protein was significantly augmented 24 hours after resistance exercise performed to failure compared to the resting fed state.

0:56:50supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Micellar casein is a slowly digested protein that induces a slower rise in plasma essential amino acids and a lower muscle protein synthesis response compared to whey protein.

"micellar casein is a slowly digested protein, so the increase in circulating essential amino acids in the blood is more sluggish than when you ingest whey protein, which is a more rapidly digestible protein. And so the whey protein gets, or is more rapidly digested, greater increases of muscle protein synthesis, and also has a greater anabolic response, greater increase in muscle protein synthesis." (said at 0:56:50)

Human randomized trials and tracer kinetic studies demonstrate that micellar casein is a slowly digested protein resulting in slower, lower peak postprandial rises in circulating essential amino acids, whereas whey protein is rapidly digested and produces higher peak essential amino acid concentrations (particularly leucine) and significantly greater acute muscle protein synthesis rates both at rest and following resistance exercise.

0:57:16supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Hydrolyzing casein to match the rapid digestion and absorption rate of whey still results in a lower muscle protein synthesis response, which can be overcome by adding free leucine.

"we hydrolyzed the casein to make it more rapidly digestible, so it was just as easily digested and absorbed as the whey, but it still had a lesser response. So that might be due to the lesser amount of leucine in casein than in whey... And we also double-checked that by adding free leucine on the casein, and we got a greater response." (said at 0:57:16)

A randomized trial in healthy older men evaluated the digestion and absorption kinetics and muscle protein synthetic response to intact casein, casein hydrolysate, and whey protein. Hydrolyzing casein increased the rate of digestion and amino acid appearance in the circulation, but muscle protein fractional synthetic rate (FSR) remained significantly lower following casein hydrolysate (0.10 ± 0.01%/h) compared to whey (0.15 ± 0.02%/h). The superior anabolic response of whey was attributed to its higher leucine content, supported by a strong positive correlation between peak plasma leucine concentrations and postprandial muscle protein synthesis.

0:57:36supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Leucine stimulates the mTOR pathway to initiate the anabolic muscle protein synthesis signaling cascade.

"leucine is an amino acid that has very strong signaling properties, so it stimulates the mTOR pathway, and therefore it sets off the whole anabolic cascade." (said at 0:57:36)

Extensive human and molecular physiology literature confirms that leucine functions as a potent nutrient-signaling molecule that directly activates the mechanistic target of rapamycin complex 1 (mTORC1) pathway. Phosphorylation of downstream targets within the mTORC1 cascade (such as p70S6K and 4E-BP1) initiates mRNA translation and stimulates skeletal muscle protein synthesis.

1:00:40supportedhightheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Boiling or cooking eggs denatures the protein and leads to faster release of amino acids into the circulation compared to consuming raw eggs.

"we did a study to see what the digestion and absorption and muscle protein synthesis is after ingesting raw eggs versus cooked eggs. Now, what is really nice to see, you have exactly the same protein, but cooking actually denatures the protein and results in much more rapid release of these amino acids in the circulation." (said at 1:00:40)

The claim is supported by randomized human trials. Heating (cooking/boiling) denatures egg protein, rendering it significantly more digestible and resulting in a higher, more rapid postprandial increase in circulating amino acids compared to consuming raw eggs. A randomized controlled trial in young men (van Loon group) demonstrated that ingesting 5 boiled eggs led to a 20% higher peak concentration of plasma essential amino acids (EAAs) than ingesting 5 raw eggs (PMID: 36774104). Classical ileal digestibility studies using stable isotopes also showed that cooking egg protein increases true ileal digestibility from ~51% (raw) to ~91% (cooked) (PMID: 9772141). Although the rate of muscle protein synthesis did not differ significantly between raw and boiled egg ingestion in the 2022 trial, the specific statement regarding protein denaturation and the more rapid release of amino acids into the circulation after cooking cooked eggs is accurate.

1:02:10supportedmoderateDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Minced meat is digested and absorbed significantly faster than intact steak.

"We provided subjects with that meat, provided as minced meat or as a steak. Huge difference in the rate of digestion and absorption. So also chewing and cutting up your food is an important factor." (said at 1:02:10)

A randomized crossover study in older men using intrinsically labeled beef directly evaluated this comparison. Consuming minced beef resulted in significantly faster digestion and absorption of meat protein-derived amino acids into the circulation compared to beef steak, with higher postprandial amino acid availability (61% vs. 49% over 6 hours) and greater whole-body protein retention.

1:06:20supportedhightheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Most plant-based proteins are deficient in one or more specific essential amino acids, most commonly methionine and lysine.

"and sometimes most of the plant-based proteins are deficient in one or more specific amino acids. That's often methionine and lysine." (said at 1:06:20)

Plant-based proteins typically have lower concentrations of specific essential amino acids compared to animal proteins and human requirement profiles. Legumes are characteristically low in sulfur-containing amino acids (particularly methionine), while cereal grains and other plant sources are commonly limited in lysine. Profiling of various commercially available plant protein isolates demonstrates that methionine and lysine concentrations are consistently lower across most plant sources compared with animal protein isolates and human skeletal muscle protein requirements.

1:06:35supportedhightheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Giving healthy subjects 30 grams of protein extract from pea, gluten, or corn stimulates muscle protein synthesis to a degree not significantly different from dairy protein.

"The last five years, we have been trying the protein extracts from pea and gluten and corn, and actually, if we give in healthy subjects, we give 30 grams, which is quite a lot of protein, we don't see a difference with dairy protein." (said at 1:06:35)

Randomized controlled trials in healthy young adults show that ingestion of 30 grams of plant-derived protein—including corn protein isolate alone or a 30 g blend combining wheat (gluten), corn, and pea protein—stimulates postprandial myofibrillar protein synthesis rates to an extent that does not differ significantly from an equivalent dose (30 g) of high-quality milk/dairy protein.

1:08:47supportedhightheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Corn protein extract has a higher leucine concentration than most animal-derived proteins.

"some, just as corn, is actually higher in leucine than most animal-derived proteins." (said at 1:08:47)

Analytical profiling of protein isolates demonstrates that corn protein has an unusually high leucine concentration (approximately 12% to 13.5% of total amino acid content). This exceeds the leucine content of typical animal-derived proteins, including whole milk (~9.0%), egg (~7.0%), beef/skeletal muscle (~7.6%), casein (~9-10%), and even whey protein isolates (~11-12%).

1:13:15supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Twenty grams of whey protein contains approximately 2 to 2.5 grams of leucine.

"20 grams for whey protein, that will be about two to two and a half grams of leucine." (said at 1:13:15)

The statement is accurate. Whey protein is notably rich in branched-chain amino acids, particularly leucine, which typically comprises approximately 10% to 12% of the total protein content by weight (yielding approximately 2.0 to 2.5 grams of leucine per 20-gram serving of whey protein). This amino acid profile is widely established in nutritional biochemistry and clinical feeding studies examining muscle protein synthesis.

1:13:23supportedmoderateDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Administering free leucine or branched-chain amino acids increases muscle protein synthesis strongly in the first 2 hours, but the response wears off much more rapidly than intact protein.

"So you can also give that as free leucine or as the branched-chain amino acids, and we've done that as well. We also see that very strong increase in muscle protein synthesis in the first two hours, but then it wears off much more rapidly." (said at 1:13:23)

Clinical tracer studies demonstrate that administering free leucine or leucine-enriched essential amino acid (EAA) mixtures produces a rapid and robust stimulation of skeletal muscle protein synthesis (MPS) within the first 1 to 2 hours following ingestion. However, because free amino acids are absorbed rapidly and clear quickly without providing a sustained whole-body pool of non-essential and essential amino acids or slower digestion kinetics, MPS returns to baseline more rapidly compared to intact protein sources (such as whey protein), which produce more prolonged hyperaminoacidemia and an extended anabolic response.

1:25:11supportedmoderateDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Human muscle research does not find evidence that an increased number of myonuclei from prior exercise training is permanently retained during detraining to facilitate muscle memory.

"seeing whether the number of nuclei in the muscle are maintained to be increased, so it's easier for the muscle to adapt to exercise. Now, there's some rodent data to suggest that; we don't find evidence for that in human muscle, so that you basically have more managers in your muscle fibers that when you put a greater stress on it, it's more easily managed. But so far we haven't seen that." (said at 1:25:11)

A systematic review and meta-analysis of human and animal studies (PMID 35961635) concluded that whereas rodent models showed myonuclear retention following atrophy, human muscle studies demonstrated a significant reduction in myonuclei and satellite cell content during detraining/atrophy, failing to support the myonuclear permanence model of muscle memory. While some subsequent human studies have observed myonuclear retention during detraining (e.g., PMID 39159314), they also found that retained myonuclei did not lead to superior muscle hypertrophy during retraining, supporting the guest's statement that evidence for this functional mechanism in humans remains unestablished.

1:29:22supportedmoderateDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Human muscle protein turnover (breakdown and synthesis) occurs at a rate of 1 to 2% per day, independent of age.

"So the first thing to say is that the turnover of muscle, so the breakdown and the synthesis of muscle, is something that occurs at 1 to 2% per day, as we started off this podcast with, and that is independent of age." (said at 1:29:22)

Human stable isotope tracer studies show that basal muscle protein fractional synthetic and breakdown rates typically range from ~0.04% to 0.08% per hour (~1% to 2% per day). Furthermore, studies comparing healthy younger and older adults demonstrate that basal muscle protein fractional synthetic rates and net muscle protein turnover are not significantly altered by age alone.

1:31:58supportedhightheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Prostate cancer patients receiving androgen deprivation therapy who engaged in resistance exercise twice a week increased muscle mass and strength compared to controls who lost muscle mass.

"Now, we thought like, "Hey, how easy is it to increase or prevent the muscle loss?" To some extent, we were modest in this, with only like two resistance exercise sessions a week. We increased muscle mass, we increased strength—control group went down. There was no loss, there was actually an increase in muscle mass, there was an increase in muscle strength." (said at 1:31:58)

The claim accurately reflects the findings of a randomized controlled trial in prostate cancer patients receiving androgen deprivation therapy (ADT). Over a 20-week period of supervised resistance exercise training (performed twice weekly in the study protocol), muscle mass and muscle strength increased in the exercise group, while the usual care control group experienced a decrease in muscle mass and strength.

1:31:59supportedmoderateDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Androgen deprivation therapy in prostate cancer patients typically causes increased fat mass, loss of muscle mass, elevated cardiovascular disease risk, and insulin resistance or diabetes.

"they get androgen deprivation therapy, so basically they get chemically castrated so that the testosterone will be gone down just completely to none. These people generally gain fat mass, lose muscle mass, and are at a heightened risk for cardiovascular disease, and often develop also insulin resistance and diabetes." (said at 1:31:59)

The speaker's statement accurately summarizes the established metabolic and body composition changes associated with androgen deprivation therapy (ADT) in patients with prostate cancer. Published clinical reviews and observational cohort evidence demonstrate that hypogonadism induced by ADT leads to increased fat mass, loss of lean muscle mass, elevated risk of cardiovascular events, and increased incidence of insulin resistance and type 2 diabetes.

1:37:11supportedhightheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Cold water immersion immediately following resistance exercise impairs acute muscle protein synthesis and reduces muscle perfusion and amino acid delivery for at least the first six hours compared to thermoneutral recovery.

"And after exercise, we put one leg in cold water and one in thermoneutral water, and we saw that the leg in the cold water did not get the same stimulation of muscle protein synthesis, and basically less of the protein would actually go to the leg—less perfusion, less stimulation of muscle protein synthesis. So at least for the first six hours, it seems evident that acute recovery, in the light of muscle protein synthesis, glycogen restoration, is actually compromised by the lower temperature." (said at 1:37:11)

The speaker accurately describes published randomized within-subject (contralateral limb) experimental studies. In healthy young adults performing resistance exercise followed by single-leg cold water immersion (8°C) versus contralateral thermoneutral water immersion (30°C), postexercise cooling significantly reduced microvascular perfusion (microvascular blood volume), lowered dietary amino acid incorporation into skeletal muscle, and blunted acute (5-hour) myofibrillar protein synthesis rates.

1:38:15supportedmoderateDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Performing 15 minutes of cold water immersion after each of six training sessions over two weeks significantly reduces cumulative muscle protein synthesis compared to non-cooled training.

"So we continued doing that for, if I'm not incorrect, over two weeks with six training sessions. And so it's six training sessions with only up to about 15 minutes of cooling... And over those two weeks, total protein synthesis in that leg that received cooling compared to the other was actually less, and actually measurably less." (said at 1:38:15)

The claim is supported by clinical trial evidence evaluating intra-individual differences in muscle protein synthesis during two weeks of resistance training with post-exercise cooling. In a randomized trial of 12 healthy young men (Fuchs et al., 2020), one leg underwent cold water immersion (8°C for 20 minutes) while the opposite leg served as control (thermoneutral water at 30°C) following resistance exercise sessions over two weeks. Cumulative daily myofibrillar protein synthesis rates measured via deuterated water over the 2-week period were significantly lower in the cold-water immersed leg (1.48 ± 0.17% day⁻¹) compared to the non-cooled control leg (1.67 ± 0.36% day⁻¹, P = 0.042). Acute 5-hour post-exercise protein synthesis rates were also significantly reduced.

1:42:18supportedmoderatetheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Approximately 5% of the connective protein fraction in skeletal muscle is composed of collagen.

"But if we get a fraction of the muscle is the connective proteins, and of those connective proteins about 5% is collagen." (said at 1:42:18)

Biochemical profiling of skeletal muscle protein subfractions indicates that the isolated muscle connective protein fraction is composed of approximately 4.4 ± 0.9% collagen relative to total protein content (compared to ~1.2% in mixed muscle tissue), with the remainder consisting of intra- and extracellular scaffolding proteins, cell adhesion molecules, and residual myofibrillar proteins.

1:42:32supportedhightheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Ingestion of 20 to 30 grams of collagen protein does not stimulate mixed muscle protein synthesis or intramuscular connective tissue protein synthesis.

"Now, so far, studies have not shown increase in muscle protein synthesis when you ingest collagen... We've done a study to see whether it increases connective protein in muscle; we don't see it, at least not with the 20 grams or the 30-gram amounts." (said at 1:42:32)

Randomized controlled trials utilizing stable isotope tracer methods show that ingesting 20 to 30 grams of collagen protein (or 15 g twice daily) does not stimulate myofibrillar muscle protein synthesis or intramuscular connective tissue protein synthesis above baseline/placebo levels, unlike high-quality complete proteins such as whey.

1:42:40supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Collagen protein composition is approximately 50% proline and glycine.

"Now, collagen is, from an amino acid composition, not a very high-quality protein because almost 50% is composed of proline and glycine, and so it has a lot less essential amino acids." (said at 1:42:40)

Collagen's primary structure consists of a repeating Gly-X-Y triplet motif in which glycine constitutes approximately 33% (every third residue) of the total amino acid sequence, and the X and Y positions are frequently occupied by proline and 4-hydroxyproline (accounting for roughly 20-22%). Together, glycine, proline, and hydroxyproline make up nearly 50% of the amino acid content of collagen. Consequently, collagen is low in essential amino acids (and lacks tryptophan entirely), giving it a lower protein quality score compared to standard complete protein sources like dairy.

1:44:40supportedhightheir own paperDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Connective tissue protein synthesis rates increase in skeletal muscle following physical activity independently of post-exercise protein or collagen intake.

"so in muscle, I think that the availability of the amino acids is not restricting the increase after physical activity, because after physical activity, we see the connective tissue protein synthesis rates go up, but it doesn't seem to be dependent on the amount of protein or collagen that you provide." (said at 1:44:40)

Randomized controlled trials using stable isotope tracers demonstrate that resistance exercise stimulates skeletal muscle connective tissue protein synthesis rates, and that this response is not augmented by post-exercise intake of protein, collagen hydrolysate, or free amino acids compared to placebo.

1:49:30supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Following ingestion of 20 grams of protein, approximately 10 grams of amino acids are released into the systemic circulation over the subsequent 4 hours.

"And then you only give like 20 g of protein, of which 10 g is released in the circulation over the next 4 hours, and that is only a spark, like maybe 15% on the total turnover, the release of amino acids in circulation." (said at 1:49:30)

Stable isotope tracer studies in humans using intrinsically labeled dietary protein demonstrate that splanchnic extraction (first-pass uptake by the gut and liver) retains roughly 45–50% of ingested amino acids. In vivo human tracer trials, including a meta-analysis of 18 randomized controlled trials across 602 participants, confirm that approximately 50% to 55% of the amino acids from an ingested protein dose (e.g., ~10–11 g from a 20 g protein dose) are released into the systemic circulation over the 4-to-5-hour postprandial window.

1:57:42supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

The human intestinal wall possesses specific transport systems capable of absorbing small peptides intact.

"Now, there are transporters for small peptides in the gut, and so they have been recognized and shown." (said at 1:57:42)

The human intestinal epithelium possesses dedicated peptide transport mechanisms, predominantly the proton-coupled oligopeptide transporter 1 (PepT1 / SLC15A1) localized to the apical brush border membrane. PepT1 mediates the electrogenic, proton-dependent transport of intact dipeptides and tripeptides derived from dietary protein digestion and peptidomimetic drugs across the intestinal wall.

2:05:21supportedhighDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Circulating hydroxyproline levels increase after ingesting collagen, but ingested hydroxyproline is not directly incorporated as a precursor into newly synthesized endogenous collagen.

"the hydroxyproline, that actually is increased in the circulation after ingesting collagen, but the hydroxyproline is not a precursor for your incorporation in your own collagen." (said at 2:05:21)

The speaker's statement accurately reflects established human pharmacokinetics and collagen biochemistry. Clinical ingestion studies show that oral collagen hydrolysate significantly and dose-dependently increases both free and peptide-bound hydroxyproline in human circulation. Furthermore, free hydroxyproline cannot be directly incorporated into newly synthesized endogenous collagen chains because there is no transfer RNA (tRNA) or codon for hydroxyproline; instead, proline is incorporated during ribosomal translation and subsequently modified to hydroxyproline post-translationally by prolyl hydroxylase enzymes within the endoplasmic reticulum.

2:05:52supportedmoderateDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

Protein synthesis rates of tissues in and around the knee—including cartilage, synovium, menisci, ACL, and PCL—are comparable in magnitude to the protein synthesis rate of skeletal muscle.

"we measured the synthesis rate of muscle, cartilage, synovia, menisci, the ACL, the PCL, so everything... and the synthesis rates were almost all in the same ballpark as muscle." (said at 2:05:52)

In an in vivo human stable-isotope tracer study of patients undergoing knee arthroplasty, fractional protein synthesis rates across various knee joint tissues were found to be comparable in magnitude to that of skeletal muscle (0.04 ± 0.01%/h). Specifically, basal protein synthesis rates were 0.04 ± 0.01%/h in cartilage, 0.04 ± 0.01%/h in menisci, 0.07 ± 0.02%/h in the ACL, 0.04 ± 0.01%/h in the PCL, and 0.13 ± 0.03%/h in synovium.

2:07:25supportedmoderateDr. Luc Van Loon: Optimizing Protein Intake & Distribution f

The direct mechanical stimulation from exercise is a much more potent driver of muscle adaptation than transient post-exercise hormonal changes in testosterone and growth hormone.

"the exercise is much more potent than the hormonal changes that you see." (said at 2:07:25)

Exercise-induced skeletal muscle hypertrophy is primarily driven by local, intrinsic mechanical signaling (mechanotransduction) and intramuscular protein synthetic pathways (such as p70S6K phosphorylation) rather than transient acute post-exercise elevations in systemic hormones like testosterone, growth hormone, or IGF-1. Clinical investigations evaluating resistance training responses have demonstrated that acute post-exercise fluctuations in circulating anabolic hormones do not correlate with or drive long-term muscle hypertrophy, whereas local mechanical loading and intracellular signaling activation directly predict muscle protein accretion.

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