Etymology 
When it comes to understanding words in Nutrition or exercise science, it is necessary to first get to the word root origin because most all the meaning of words lies in its origin and then the word itself explain.

The word protein came from Greek, which means “primary” or “first”. What does it indicate? It shows there is something in Nutrition which is primary or important than any other, called ‘PROTEIN’ and hence sometime animal protein is also unknown as first class Protein.

The Meaning of essential.

Nitrogen – Introduction

Protein is the only source of nitrogen, and all living things need nitrogen.

Function of protein in our body.

• Structural Proteins (Membranes, cartilages, Connective tissues).
• Transport Proteins.
• Direct biochemical reactions (enzymes),
• Defend the body against infection (antibodies),
• Control metabolic processes (hormones).
• Contractile Proteins – are responsible for movement.

Introduction

A 2015 study,” dietary essentially of “nutritionally non-essential amino acids” for animals and humans”.

All 20 AAS are required to build muscle tissue.

A 2017 REVIEW STUDY,” BRANCHED-CHAIN AMINO ACIDS AND MUSCLE PROTEIN SYNTHESIS IN HUMANS: MYTH OR REALITY?”

All EAA are required for the effect to persist.

A 2003 STUDY  “ESSENTIAL AMINO ACIDS ARE PRIMARILY RESPONSIBLE FOR THE AMINO ACID STIMULATION OF MUSCLE PROTEIN ANABOLISM IN HEALTHY ELDERLY ADULTS”.

 Muscle protein synthesis is stimulated primarily by the EAA in the food you ingest.

A 2013 STUDY, “ESSENTIAL AMINO ACIDS ARE PRIMARILY RESPONSIBLE FOR THE AMINO ACID STIMULATION OF MUSCLE PROTEIN ANABOLISM IN HEALTHY ELDERLY ADULTS”.

Quantity of Amino Acid in Foods and Its Importance.

Digestive System – Introduction

Enzymes- Introduction

Liver -Introduction 

 A 2011 RAT STUDY,“ALTERNATION BETWEEN DIETARY PROTEIN DEPLETION AND NORMAL FEEDING CAUSE LIVER DAMAGE IN MOUSE”.

Damage may be seen when cycling periods (5 days) of sufficient protein intake, and periods of protein malnutrition.

In a 2012 RAT STUDY, ‘re feeding with a high-protein diet after a 48 h fast causes acute hepatocellular injury in mice”.

Similar effects were seen after 48 hours of fasting when fed a diet containing 40-50% casein.

 A 2012 RAT STUDY,“THE CHANGES OF HEPATIC METALLOTHIONEIN SYNTHESIS AND THE HEPATIC DAMAGE INDUCED BY STARVATION IN MICE”.

 A 2012 RAT STUDY,“THE CHANGES OF HEPATIC METALLOTHIONEIN SYNTHESIS AND THE HEPATIC DAMAGE INDUCED BY STARVATION IN MICE”.

The 35% and 50% casein groups had higher AST and ALT levels than the lower protein controls, effectively controlling for refeeding syndrome in general and its adverse effects on liver enzymes.

 A 1968 STUDY,“THE EFFECT OF DIETARY PROTEIN ON CARCINOGENESIS OF AFLATOXIN”.

 A 1983 RAT STUDY,“EFFECT OF HIGH AND LOW DIETARY PROTEIN ON THE DOSING AND POST DOSING PERIODS OF AFLATOXIN B1-INDUCED HEPATIC PARANEOPLASTIC LESION DEVELOPMENT IN THE RAT”.

 A 1992 RAT STUDY,“EFFECT OF DIETARY PROTEIN LEVEL ON AFLATOXIN B1 ACTIONS IN THE LIVER OF WEANLING RATS”.

A 1992 RAT STUDY,“INFLUENCE OF DIFFERENT LEVELS OF DIETARY CASEIN ON INITIATION OF MALE RAT LIVER CARCINOGENESIS WITH A SINGLE DOSE OF AFLATOXIN B1”.

• Aflatoxin (a toxic mould that is produced from some species of nuts and seeds) is known to be more carcinogenic (cancer producing) when the diet is very high in protein, and subsequently less potent in diets lower in protein.
• This is due to the toxin being bioactivated by the P450 enzyme system, which has its overall activity increased when dietary protein increases. 
• These phenomena also have effects on drugs (Warfarin) metabolized by P450, in which the dosage may need to be increased due to faster metabolism.

 A 1974 RAT STUDY,“PLASMA ENZYME ACTIVITIES IN RATS WITH DIET-INDUCED ALTERATIONS IN LIVER ENZYME ACTIVITIES”.

A diet of 35% casein led to increased ALT and AST levels in rats.

FINAL THOUGHTS

•  Some preliminary evidence that high protein refeeding (35-50%) after 48 hours of fasting may harm the liver. Shorter fasts were not examined.
• In healthy individuals and rats, there is no evidence to suggest a relatively normal style of protein intake is harmful to the liver when habitually consumed as part of the diet.
• It is typically seen as safe to consume protein given you have a healthy liver.

Bioavailability – Introduction

The bioavailability of nutrients in the body is dependent on enhancers and inhibitors.

• Plant proteins have long been thought to be inferior to animal proteins due to their reduced digestibility and lower percentage of essential amino acids (EAA), including critical anabolic drivers like branched-chain amino acids like leucine.
• They rate and rank proteins based on two criteria:Digestibility, Bioavailability, and amino acid profile.
• The digestibility rate of animal-based proteins is higher than 90% whereas plant-based sources (legumes and grains) are 60–80%.
• To determine the PDC AAS of a protein, you analyse the faeces. To determine the DIAAS of a protein, you analyse the content of the ileum. In other words, PDC AAS looks at how much protein was absorbed after it has gone through your small and large intestines, whereas DIAAS looks at how much protein was absorbed after it has left the small intestine.
• Fibre and anti-nutrients (trypsin inhibitors, phytates, tannins, etc.), can all affect how much of your protein you absorb.
• Plant-based protein powders, however, are mostly free of antinutrients and so have digestibility rates similar to those of animal-based proteins.

A 2004 9 WEEKS STUDY,” SOY VERSUS WHEY PROTEIN BARS: EFFECTS ON EXERCISE TRAINING IMPACT ON LEAN BODY MASS AND ANTIOXIDANT STATUS”.

FINAL THOUGHTS

• The lower leucine and EAA content of plant-based proteins helps explain why several studies have reported lower rates of MPS from soy protein powders and beverages than from whey protein, skim milk, whole milk with cheese, and lean beef.
• Differences in MPS do appear to translate to differences in lean mass when modest supplemental protein doses are used (about 20 g/day), when higher doses are used (33–50 g/day), animal-based (whey) and plant-based (soy, rice) supplemental proteins appear to impact lean mass similarly.
• Consuming more protein overall appears to offset the lower quality of the plant-based proteins.

The Recommended Daily Allowance (RDA) for protein is 0.8 g/kg. This figure was derived from nitrogen balance studies on sedentary individuals. It formally became part of the public health guidelines in 1980. It’s now 2021, and the RDA for protein has changed no adjustments for athletes or physically active individuals, no increase for the elderly.

Protein requirements are inversely proportional to energy intake___ Donald k layman.

Daily Total Protein Intake.

Distribution of Protein throughout the day/Meal Timing /Meal Frequency.

The ranges listed are derived from studies using whey protein isolated, high bioavailable, rich in EAA. These values suggest a protein-intake threshold for maximally stimulating MPS, there is no known threshold for whole-body protein balance.

A 2016 CLINICAL TRIAL STUDY,”THE ANABOLIC RESPONSE TO A MEAL CONTAINING DIFFERENT AMOUNTS OF PROTEIN IS NOT LIMITED BY THE MAXIMAL STIMULATION OF PROTEIN SYNTHESIS IN HEALTHY YOUNG ADULTS.”

Meals with lean beef found that 40 and 70 grams of protein (0.5 and 0.8 g/kg) led to similar increases in MPS, but that 70 grams led to greater increases in whole-body protein synthesis and greater decreases in whole-body protein breakdown.

A 2020  12 WEEK, PARALLEL-GROUP, RANDOMIZED CLINICAL TRIAL STUDY,”EVENLY DISTRIBUTED PROTEIN INTAKE OVER 3 MEALS AUGMENTS RESISTANCE EXERCISE–INDUCED MUSCLE HYPERTROPHY IN HEALTHY YOUNG MEN.”

Consuming a protein-enriched meal at breakfast & less protein at dinner while achieving an adequate overall Protein is more effective than consuming more protein at dinner.

A 2019  12 WEEK, PARALLEL-GROUP, RANDOMIZED CLINICAL TRIAL STUDY,”THE IMPACT OF PRE-SLEEP PROTEIN INGESTION ON THE SKELETAL MUSCLE ADAPTIVE RESPONSE TO EXERCISE IN HUMANS: AN UPDATE”.

Protein ingestion before sleep is an effective interventional strategy to increase muscle protein synthesis rates during overnight sleep.

A 2016,RANDOMIZED,DOUBLE-BLIND,CROSSOVER  STUDY,”THE RESPONSE OF MUSCLE PROTEIN SYNTHESIS FOLLOWING WHOLE-BODY RESISTANCE EXERCISE IS GREATER FOLLOWING 40 G THAN 20 G OF INGESTED WHEY PROTEIN”.

#35#RESISTANCE-TRAINED

Data indicate that ingestion of 40 g whey protein following whole-body resistance exercise stimulates a greater MPS response than 20 g in young resistance-trained men.

Q:is it necessary to distribute protein evenly throughout the day?

 A 2020 12 WEEKS STUDY, PARALLEL-GROUP, RANDOMIZED CLINICAL TRIAL,EVENLY DISTRIBUTED PROTEIN INTAKE OVER 3 MEALS AUGMENTS RESISTANCE EXERCISE–INDUCED MUSCLE HYPERTROPHY IN HEALTHY YOUNG MEN.(PMID: 32321161)

# DEXA # 26 non-resistance trained males (early 20s) #2 sets x 10 reps # Muscle Failure #3 days/week #2,500 calories #90-100 grams of protein/day#Cohen’s d effect size.

Both protein groups gained a significant amount of muscle mass. However, the High-Protein Breakfast group tended to gain more muscle mass.

Body fat % reduced in both groups, were not different, and overall body fat mass loss was very little, around half a pound (.23 kg)

The High-Protein Breakfast group gained 5.5 pounds (2.5 kg) of muscle mass, while the Low Protein Breakfast group gained 3.9 pounds (1.7 kg) of muscle mass. While the high-Protein Breakfast group gained 40% more muscle mass than the Low Protein Breakfast group, the difference did not reach the level of statistical significance (p < 0.05), but it was very close with a p-value of 0.056.

Strength:

• this was the first study to report that when total daily protein intake is the same, more muscle is built when that protein is more evenly distributed throughout the day.
• The only significant differences between the two groups were the amount of protein eaten at breakfast and at dinner. Therefore, any difference in muscle gain is likely attributed to when they ate their protein.
• The Low Protein Breakfast group only ate ~8 grams of protein at breakfast, while the High-Protein Breakfast group ingested nearly 3 times more (~23 grams) at breakfast. One group did not ingest more total calories or more total daily protein than the other group.

Limitations:

• Subjects recorded their food intake for 3 days (2 weekdays and 1 weekend day) at the beginning of the study and again at the end of the study.
• Because there was no measurement of total body water, changes in muscle mass might have been due to hydration levels changing only males, no female subjects.

“ANABOLIC WINDOW”-A matter of debate

A 2013 META-ANALYSIS STUDY , “THE EFFECT OF PROTEIN TIMING ON MUSCLE STRENGTH AND HYPERTROPHY: A META-ANALYSIS”.

Regarding hypertrophy, total daily protein intake is still the most important component, results disprove the commonly held belief that the timing of protein intake in and around a training session is critical to muscular adaptations and indicate that consuming adequate protein with resistance exercise is the key factor for maximizing muscle protein growth.

OTHER SIDE OF COIN

A 1997 STUDY,  “AN ABUNDANT SUPPLY OF AMINO ACIDS ENHANCES THE METABOLIC EFFECT OF EXERCISE ON MUSCLE PROTEIN”.

 A 2014 REVIEW STUDY,  “Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation”.

 A 2017 REVIEW STUDY,  “International society of sports nutrition position stand: nutrient timing”.

 A 2013  BOOK FOOD, NUTRITION AND SPORTS PERFORMANCE III BY GARY SLATER & STUART M. PHILLIPS,  “CHAPTER- NUTRITION GUIDELINES FOR STRENGTH SPORTS: SPRINTING, WEIGHTLIFTING, THROWING EVENTS, AND BODYBUILDING”.

Acute increases in muscle protein synthesis after training are greater with the ingestion of protein.

A 2013 REVIEW STUDY , “NUTRIENT TIMING REVISITED: IS THERE A POST-EXERCISE ANABOLIC WINDOW?”.

 It has yet to be established that this acute spike in protein synthesis after training is necessary for optimal growth and recovery over the long term.

The “post-exercise anabolic window” concept was brought to the general fitness & bodybuilding audience in the early 2000s, thanks to Ivy and Portman’s research, and their popular paperback Nutrient Timing: The Future of Sports Nutrition.

Ivy and Portman’s claims, on the other hand, were based on short-term anabolic response experiments that evaluated muscle protein synthesis (MPS) and glycogen resynthesise. Longitudinal studies that lasted many weeks or months and investigated the effects of protein timing on muscle adaptations to resistance exercise revealed a different tale.

A 2016 DOUBLE BLIND CROSSOVER RCT STUDY, “THE RESPONSE OF MUSCLE PROTEIN SYNTHESIS FOLLOWING WHOLE-BODY RESISTANCE EXERCISE IS GREATER FOLLOWING 40 G THAN 20 G OF INGESTED WHEY PROTEIN”.

A 40-gram dose of whey protein isolate taken immediately after training stimulated MPS to a greater extent than a 20-gram dose.

NOTE:Young resistance-trained adults after high-volume full-body resistance exercise.

A 2018 REVIEW“IS THERE A POST WORKOUT ANABOLIC WINDOW OF OPPORTUNITY FOR NUTRIENT CONSUMPTION? CLEARING UP CONTROVERSIES”.

Nutrient timing within the “anabolic window” (within an hour postexercise) was more important than totals by the end of the day.

A 2012 STUDY,“DAYTIME PATTERN OF POST-EXERCISE PROTEIN INTAKE AFFECTS WHOLE-BODY PROTEIN TURNOVER IN RESISTANCE-TRAINED MALES”.

This study found that ingesting protein every 3-hours was the most effective method for maintaining a positive protein balance. 12-hour net protein balance due to feeding strategy.

A 2021 A SYSTEMATIC REVIEW AND META-ANALYSIS STUDY,“THE EFFECT OF CONSUMING CARBOHYDRATE WITH AND WITHOUT PROTEIN ON THE RATE OF MUSCLE GLYCOGEN RE-SYNTHESIS DURING SHORT-TERM POST-EXERCISE RECOVERY”.

Protein co-ingested with carbohydrate does not speed up post-exercise glycogen resynthesise compared to carbohydrate alone.

A 2013 A META-ANALYSIS STUDY,“THE EFFECT OF PROTEIN TIMING ON MUSCLE STRENGTH AND HYPERTROPHY: A META-ANALYSIS”.

• Results disprove the commonly held belief that the timing of protein intake in and around a training session is critical to muscular adaptations, and indicate that consuming adequate protein with resistance exercise is the key factor for maximizing muscle protein growth.
•  Regarding hypertrophy, total protein intake was the strongest predictor.

Q:Which protein is superior for improving body composition and strength after a workout: whey, chicken, beef, or casein?

A:Evidence thus far does not indicate that the specific post-workout protein source makes a significant difference.

A 2018 RCT 8-WEEK STUDY,“THE EFFECTS OF BEEF, CHICKEN, OR WHEY PROTEIN AFTER WORKOUT ON BODY COMPOSITION AND MUSCLE PERFORMANCE”.

#41MEN & WOMEN#1RM#DEXA

All three protein groups (beef, chicken, or whey protein) significantly increased lean body mass, and significantly decreased fat mass, with no significant differences between groups.

NOTE:The chicken and beef protein hydrolyse powders were used instead of these proteins in their native/flesh form.

A 2019 RCT  DOUBLE-BLIND, PARALLEL-GROUP DESIGN STUDY,“MYOFIBRILLAR AND MITOCHONDRIAL PROTEIN SYNTHESIS RATES DO NOT DIFFER IN YOUNG MEN FOLLOWING THE INGESTION OF CARBOHYDRATE WITH MILK PROTEIN, WHEY, OR MICELLAR CASEIN AFTER CONCURRENT RESISTANCE- AND ENDURANCE-TYPE EXERCISE”.

#48MEN#BLOOD AND MUSCLE BIOPSIES

A 2011 RCT  8-WEEK STUDY,“WHEY AND CASEIN LABELED WITH L-[1-13C]LEUCINE AND MUSCLE PROTEIN SYNTHESIS: EFFECT OF RESISTANCE EXERCISE AND PROTEIN INGESTION”.

A 2004 RCT STUDY,“INGESTION OF CASEIN AND WHEY PROTEINS RESULT IN MUSCLE ANABOLISM AFTER RESISTANCE EXERCISE”.

Acute short-term response studies comparing these proteins consistently found no change in MPS or net protein balance when consumed post-exercise.

                                                             Longitudinal studies

A 2006 RCT  DOUBLE-BLIND, 10 WEEK STUDY,“THE EFFECT OF WHEY ISOLATE AND RESISTANCE TRAINING ON STRENGTH, BODY COMPOSITION, AND PLASMA GLUTAMINE”.

The study showed hydrolysed whey isolate group still achieved significantly greater improvements in strength compared to the casein group.

POTENTIAL FOR BIAS:The lead investigator was also the research director of the company that provided the whey protein product used in the study.

A 2013 RCT  DOUBLE-BLIND, 8 WEEK STUDY,“THE EFFECTS OF PRE- AND POST-EXERCISE WHEY VS. CASEIN PROTEIN CONSUMPTION ON BODY COMPOSITION AND PERFORMANCE MEASURES IN COLLEGIATE FEMALE ATHLETES”.

A 2013 RCT  DOUBLE-BLIND, 9 WEEK STUDY,“EFFECTS OF POSTEXERCISE PROTEIN INTAKE ON MUSCLE MASS AND STRENGTH DURING RESISTANCE TRAINING: IS THERE AN OPTIMAL RATIO BETWEEN FAST AND SLOW PROTEINS?”.

NO significant difference between whey and casein ingested pre- and post-exercise.

FINAL THOUGHTS

• Protein before exercise can enhance post-exercise energy expenditure more than carbs, if these short-term benefits may be seen as improvements in body composition are a matter of further research.
• Protein and carbohydrates eaten during exercise (intra workout) can reduce muscle protein breakdown; however, this effect is restricted to overnight fasting and the lack of pre-workout nutrition.
• The anabolic effect of a protein-rich meal is 3–5 hours, Instead of focusing on the “anabolic window” the period between the pre- & post-workout meal (the per workout period) should be the focus.
• After a bout of resistance exercise, protein turnover (myofibrillar MPS and anabolic signalling) can remain elevated for 24–48 hours.
• Muscle hypertrophy occurs primarily as a result of increases in myofibrillar MPS after muscle damage has been reduced ( 24-48 post-exercise period).
• Small research in this area indicates that whole eggs are more acute and chronic to anabolic than a protein-equated dose of egg whites ingested after exercising.
• Protein consumption alone can activate muscle protein synthesis (MPS) to a certain extent, protein with resistance exercise is superior.
• Untrained individuals may see increases in protein synthesis rates for up to 24–48 hours, whereas trained individuals see protein synthesis rates drop within 4-hours of training.
• Resistance training experience actually shortened the anabolic window, even after only 8-weeks of training.
• Protein timing get important as individuals with training experience.

LOGIC OR HYPOTHESIS

This notion of protein came partly from early studies that observed increased nitrogen losses in the urine with increased protein intakes. 

A 2009 RCT  STUDY,”INGESTED PROTEIN DOSE RESPONSE OF MUSCLE AND ALBUMIN PROTEIN SYNTHESIS AFTER RESISTANCE EXERCISE IN YOUNG MEN”.

Healthy young men found that eating more than 20 grams of whole-egg protein didn’t further increase MPS.

A 2009 RCT  STUDY,”A MODERATE SERVING OF HIGH-QUALITY PROTEIN MAXIMALLY STIMULATES SKELETAL MUSCLE PROTEIN SYNTHESIS IN YOUNG AND ELDERLY SUBJECTS”.

In younger and older people, found that 90 grams of protein from 90% lean beef didn’t increase MPS more than did 30 grams.       

This was thought to mean that the extra protein was wasted.

Well, our body doesn’t use Protein directly; instead, it breaks it down into its constituent amino acids and uses those to make its own proteins. When we eat more protein, our body can afford to replace more of its damaged or oxidized proteins, so that your protein synthesis and breakdown are both increased.

Our body doesn’t use dietary protein only to make muscle, or even only to make other proteins. It also uses the nitrogen from the dietary protein’s amino acids to synthesize important non-protein molecules, such as purines and pyrimidines, the building blocks for nucleic acids such as DNA and RNA.our small intestines can absorb and store a large amount of amino acids, ready to be used when your body needs them.

Hence, eating more protein increases your body’s protein turnover. The raised levels of urinary nitrogen then reflect, not a waste of eaten protein, but an increase in the breakdown of your body’s damaged or oxidized proteins.

Note: elevated levels of urinary nitrogen can also indicate health issues, such as problems with kidney function.

                     FINAL THOUGHTS

• Having protein in similar doses throughout the day is the most effective way to achieve maximum growth.
• Muscle protein breakdown is the other side of protein turnover. 
  Both processes, Muscle Protein Synthesis & Muscle Protein Breakdown, occur in constant, dynamic cycles.
• Muscle growth occurs as a result of  Muscle Protein Synthesis  exceeding Muscle Protein Breakdown over time.
• From a practical viewpoint, less than three protein feedings per day are unlikely to optimise hypertrophy due to gastrointestinal problems associated with large meals, as well as a mechanistic standpoint the anabolic “ceiling” shown in the restricted MPS increases per feeding.
• Obtaining any degree of muscle growth is not the same as optimising rates of muscle growth.
  Because there are no direct comparisons of different meal frequencies in resistance trainees in studies, the protein feeding frequency and distribution will remain a source of debate.
• Eating more protein may not necessarily translate to greater muscle-protein turnover and growth, but since muscle tissue accounts for only 25–30% of whole-body protein turnover, the additional protein is not “wasted” (a common myth).
• To maximize lean mass, active adults should consume 1.6–2.2 g/kg/day spread across four meals (0.4–0.6 g/kg/meal)

Q: Do we require more protein while losing fat to maintain muscle mass?

A: Yes, Protein needs rise with the severity of the calorie deficit and the level of leanness of the dieter.

A 2017 REVIEW STUDY, “INTERNATIONAL SOCIETY OF SPORTS NUTRITION POSITION STAND: DIETS AND BODY COMPOSITION”.

Protein needs rise with the severity of the calorie deficit and the level of leanness of the dieter.

A 2018 REVIEW STUDY, “HOW MUCH PROTEIN CAN THE BODY USE IN A SINGLE MEAL FOR MUSCLE-BUILDING? IMPLICATIONS FOR DAILY PROTEIN DISTRIBUTION”.

In eucaloric (weight maintenance) conditions,  low protein intakes still can threaten muscle mass.

A 2015 RCT  STUDY,“EFFECT OF PROTEIN OVERFEEDING ON ENERGY EXPENDITURE MEASURED IN A METABOLIC CHAMBER”

In hypercaloric (weight gain) conditions, low protein intakes still can threaten muscle mass.

A 2017 REVIEW STUDY,“PROTEIN RECOMMENDATIONS FOR WEIGHT LOSS IN ELITE ATHLETES: A FOCUS ON BODY COMPOSITION AND PERFORMANCE.”

Concluded that an appropriate range of protein intake for athletes in hypocaloric conditions is 1.6-2.4 g/kg.

A 2013 SYSTEMATIC REVIEW STUDY,“ DIETARY PROTEIN DURING CALORIC RESTRICTION IN RESISTANCE TRAINED LEAN ATHLETES: A CASE FOR HIGHER INTAKES.”

Concluded that 2.3-3.1 g/kg of fat-free mass (FFM) was appropriate for resistance-trained subjects in hypocaloric conditions, with needs escalating according to the severity of the deficit and leanness level.

NOTE: Out of the six studies in the review, only three examined highly trained competitive athletes, and only one study examined competitive bodybuilders.

A 2010 11 WEEKS STUDY,“ANABOLIC AND CATABOLIC HORMONES AND ENERGY BALANCE OF THE MALE BODYBUILDERS DURING THE PREPARATION FOR THE COMPETITION.”

The pre contest protein intake of drug-free, world-class bodybuilders ranged 2.48-2.68 g/kg.

NOTE:Because these are observational data, they cannot be used to prove causality.

A 2018 STUDY,“NUTRITIONAL STRATEGIES OF HIGH LEVEL NATURAL BODYBUILDERS DURING COMPETITION PREPARATION.”

Elite-level drug-free bodybuilding men & women who placed in the top-5 had pre-contest protein intakes of 3.3 & 2.8 g/kg, respectively.

NOTE:Because these are observational data, they cannot be used to prove causality.

A 2007 12 WEEKS STUDY,” EFFECT OF PROTEIN SOURCE AND RESISTANCE TRAINING ON BODY COMPOSITION AND SEX HORMONES”.

A 2005 12 WEEKS STUDY, EFFECT OF AN ENERGY-RESTRICTED, HIGH-PROTEIN, LOW-FAT DIET RELATIVE TO A CONVENTIONAL HIGH-CARBOHYDRATE, LOW-FAT DIET ON WEIGHT LOSS, BODY COMPOSITION, NUTRITIONAL STATUS, AND MARKERS OF CARDIOVASCULAR HEALTH IN OBESE WOMEN.

Subjects with high triglycerides lost more fat on the high-protein diet.

A 2003 16 WEEKS STUDY,  “EFFECT OF A HIGH-PROTEIN, ENERGY-RESTRICTED DIET ON BODY COMPOSITION, GLYCEMIC CONTROL, AND LIPID CONCENTRATIONS IN OVERWEIGHT AND OBESE HYPERINSULINEMIC MEN AND WOMEN”.

A 2002 12 WEEKS CLINICAL TRIAL STUDY,EFFECT OF A HIGH-PROTEIN, HIGH-MONOUNSATURATED FAT WEIGHT LOSS DIET ON GLYCEMIC CONTROL AND LIPID LEVELS IN TYPE 2 DIABETES.

Both studies noted, however, that lean mass was better preserved in women (but not men) on a high-protein diet.

A 2004 68 WEEKS (12 WEEKS OF ENERGY RESTRICTION) STUDY,  LONG-TERM EFFECTS OF A HIGH-PROTEIN, LOW-CARBOHYDRATE DIET ON WEIGHT CONTROL AND CARDIOVASCULAR RISK MARKERS IN OBESE HYPERINSULINEMIC SUBJECTS.

A greater weight loss (nearly entirely from fat) in the high-protein group (men and women).

A 2012 12 MONTHS,”EFFECTS OF PROTEIN INTAKE AND GENDER ON BODY COMPOSITION CHANGES: A RANDOMIZED CLINICAL WEIGHT LOSS TRIAL”.

The high-protein group lost significantly more fat than did the low protein group when calories were kept equal, although men inherently lost more weight as a percentage of body fat.

A 2008 20 WEEKS ,”LEAN MASS LOSS IS ASSOCIATED WITH LOW PROTEIN INTAKE DURING DIETARY-INDUCED WEIGHT LOSS IN POSTMENOPAUSAL WOMEN”.

More lean mass being lost when dietary protein is lower, despite the caloric deficit being similar.

A 2011 6 MONTHS ,”THE EFFECTS OF A HIGHER PROTEIN INTAKE DURING ENERGY RESTRICTION ON CHANGES IN BODY COMPOSITION AND PHYSICAL FUNCTION IN OLDER WOMEN”.

The addition of 50g whey protein twice a day to this calorically restricted diet induced more weight loss (-8.0% ± 6.2%) than did add 50g carbohydrate despite calories being the same.

 A 2008 20 WEEKS RCT STUDY,”EFFECTS OF DIETARY PROTEIN ON THE COMPOSITION OF WEIGHT LOSS IN POST-MENOPAUSAL WOMEN”.

15% protein (in relation to overall calories) against 30% protein found that the low protein group lost more weight with 37.5% of it being lean mass, while the higher protein group had a slightly lesser rate of weight loss with approximately half as much lean mass lost .

 A 2008 12 WEEKS SINGLE BLIND PLACEBO-CONTROLLED RCT STUDY,”A CONTROLLED TRIAL OF PROTEIN ENRICHMENT OF MEAL REPLACEMENTS FOR WEIGHT REDUCTION WITH RETENTION OF LEAN BODY MASS.”

 A 2009  DATA FROM THREE, 12 WEEK META-ANALYSIS STUDY,”HIGH PROTEIN DIETS DECREASE TOTAL AND ABDOMINAL FAT AND IMPROVE CVD RISK PROFILE IN OVERWEIGHT AND OBESE MEN AND WOMEN WITH ELEVATED TRIACYLGLYCEROL”.

• The high-protein group not only lost more body fat mass, but also experienced a reduction in LDL cholesterol and total cholesterol not seen in the low protein group.
• With higher protein, reducing losses in lean mass.

A 2011 16 WEEKS RCT STUDY,”INCREASED CONSUMPTION OF DAIRY FOODS AND PROTEIN DURING DIET– AND EXERCISE-INDUCED WEIGHT LOSS PROMOTES FAT MASS LOSS AND LEAN MASS GAIN IN OVERWEIGHT AND OBESE PREMENOPAUSAL WOMEN”.

Greater consumption of protein and dairy foods is associated with more favourable body composition changes during weight loss.

A 2003 10 WEEKS CLINICAL TRIAL STUDY,”EFFECTS OF PROTEIN  VS. CARBOHYDRATE-RICH DIETS ON FUEL UTILISATION IN OBESE WOMEN DURING WEIGHT LOSS”.

A 2012 2 YEARS RCT STUDY,”EFFECTS OF 4 WEIGHT-LOSS DIETS DIFFERING IN FAT, PROTEIN, AND CARBOHYDRATE ON FAT MASS, LEAN MASS, VISCERAL ADIPOSE TISSUE, AND HEPATIC FAT: RESULTS FROM THE POUNDS LOST TRIAL”.

High-protein diets induce more weight loss overall.

A 2012 A SYSTEMATIC REVIEW AND META-ANALYSIS STUDY,”EFFECTS OF HIGHER- VERSUS LOWER-PROTEIN DIETS ON HEALTH OUTCOMES: A SYSTEMATIC REVIEW AND META-ANALYSIS”.

74 randomized controlled trials showed that eating a higher protein diet (27% vs. 18% of calories on average) significantly reduced several cardio metabolic risk factors, including body weight, BMI, waist circumference, blood pressure, triglycerides, and fasting insulin, while also significantly increasing HDL-cholesterol and satiety.

FINAL THOUGHTS

• A strong body of evidence supports the claim that a high-protein diet can facilitate dietary adherence, health improvement, and long-term fat loss.

A 2018 A SYSTEMATIC REVIEW, META-ANALYSIS AND META-REGRESSION STUDY, THE EFFECT OF PROTEIN SUPPLEMENTATION ON RESISTANCE TRAINING-INDUCED GAINS IN MUSCLE MASS AND STRENGTH IN HEALTHY ADULTS.

Maximizing muscle growth can be achieved with 1.6-2.2 g/kg (0.7-1.0 g/lb). (the largest meta-analysis to date )

This analysis excluded trials involving hypocaloric conditions, highly trained, athletic, or competitive populations.

A 2012 SINGLE-BLIND, RCT 12 WEEKS STUDY, “EFFECT OF DIETARY PROTEIN CONTENT ON WEIGHT GAIN, ENERGY EXPENDITURE, AND BODY COMPOSITION DURING OVEREATING: A RANDOMIZED CONTROLLED TRIAL.”

Caloric expenditure, total weight, and lean mass increased with protein as a percentage of caloric intake.

A 2003 16 WEEKS WEEKS STUDY, “ EFFECT OF A HIGH-PROTEIN, ENERGY-RESTRICTED DIET ON BODY COMPOSITION, GLYCEMIC CONTROL, AND LIPID CONCENTRATIONS IN OVERWEIGHT AND OBESE HYPERINSULINEMIC MEN AND WOMEN.”

 Replacing carbohydrate with protein from meat, poultry, and dairy foods has beneficial metabolic effects and no adverse effects on markers of bone turnover or calcium excretion.

CLAIM:Since resting muscle burns about 13 kcal/kg (6 kcal/lb) per day,only a tiny surplus is required to build muscle. 

DEBUNK:The resting value of 13 kcal/kg does not account for non-exercise & exercise activity increases, and thus should not be used for programming caloric surpluses for muscle growth.

A 2017  COMPARATIVE STUDY,DIETARY PROTEIN INTAKE AND DISTRIBUTION PATTERNS OF WELL-TRAINED DUTCH ATHLETES.

Elite-level Dutch strength athletes (71 subjects) had a protein intake that averaged 1.8 g/kg in those who used protein supplements, and 1.5 g/kg in those who did not.

                                  Men                            Women

Throwing:         1.3-2.4 g/kg                   1.1-2.5 g/kg

Sprinting:            1.5 g/kg                       1.7 g/kg

Weightlifting:  1.3-3.2 g/kg                    [no data]

A 2011 STUDY,NUTRITION GUIDELINES FOR STRENGTH SPORTS: SPRINTING, WEIGHTLIFTING, THROWING EVENTS, AND BODYBUILDING.

The protein intakes of elite-level male and female bodybuilders were 1.7-2.4 g/kg & 1.5-2.0 g/kg, respectively. 

A 2015 REVIEW STUDY, DIETARY INTAKE OF COMPETITIVE BODYBUILDERS.

Reported a range of 157 g/day (1.9 g/kg/day) to 406 g/day (4.3 g/kg/day) among a mix of drug-free and enhanced competitive bodybuilders.

A 22 ± 9 WEEKS STUDY, NUTRITIONAL STRATEGIES OF HIGH LEVEL NATURAL BODYBUILDERS DURING COMPETITION PREPARATION.

Reported that in high-level drug-free bodybuilders, pre-contest protein intakes of men & women who placed in the top-5 were 3.3 & 2.8 g/kg, respectively. Protein intake of men & women who placed out of the top-5 were 2.7 & 2.9 g/kg, respectively.

Protein Calculation

CURRENT BODYWEIGHT VS. TARGET BODY WEIGHT VS. LEAN MASS

1) Protein requirements based on total bodyweight predominate the peer reviewed literature.

Eg: CURRENT BODY WEIGHT/kg  X  PROTEIN GRAM 

The pitfall here is that it’s possible to overshoot or undershoot estimated needs if someone is highly over- or underweight.

2) Protein intake on goal body weight or target body weight.

Eg: TARGET BODY WEIGHT/kg  X PROTEIN GRAM

Good to use target body weight for  highly over-or underweight individuals.

3) Protein intake on lean mass or fat-free mass (FFM), a reasonable range for maximizing muscle growth is 1.8-2.6 g/kg FFM. This range is derived from IAAO data.

Eg: LEAN MASS OR FAT-FREE MASS/kg X PROTEIN GRAM

Can be put to trial and adjusted according to individual response.

4) A quick-and-dirty estimate of protein

Eg: HEIGHT IN CENTIMETERS/kg  X PROTEIN GRAM

The pitfall here is that it’s possible to overshoot for shorter individuals.

It is right for taller individuals.

FINAL THOUGHTS

• • • Begin with 1.6-2.4 g/kg of total body weight and gradually increase to 2.4-3.3 g/kg of total body weight as you get leaner.

No.

A 2020 REVIEW STUDY,“SARCOPENIA: A CONTEMPORARY HEALTH PROBLEM AMONG OLDER ADULT POPULATIONS”. 

• Sarcopenia is one of the greatest health threats faced by older adults.
• A loss of muscle mass generally begins at ~50 years and progresses at ~0.8% per year.
• Strength decline is ~2–3% per year. 
• At 70 years of age, there is the potential for a 16% loss of muscle mass and 50% drop in strength compared to younger adulthood.

A 2019 REVIEW STUDY,“DIETARY PROTEIN QUANTITY,QUALITY,AND EXERCISE ARE KEY TO HEALTHY LIVING: A MUSCLE-CENTRIC PERSPECTIVE ACROSS THE LIFESPAN”. 

• To optimize the retention of muscle mass, especially in the elderly. The range is 1.2-1.5 g/kg which is very close to the 1.2-1.6 g/kg for preserving muscle mass and optimizing metabolic health through the ageing process in the general population. 
• This finding is based on RCT that consistently favour higher protein intakes for improving body composition and a wide range of cardio metabolic health parameters.

Anabolic resistance is characterised by decreased response of protein/amino acid feeding and exercise in muscle protein synthetics.

An age-related phenomenon that contributes to the decline of muscle mass and function.

  “use it or lose it” its principle of Muscle

Protein requirements: 1.0-1.2 g/kg for over age 65 healthy folks,1.2-1.5 g/kg in cases of acute or chronic illnesses,2.0 g/kg for those with severe illnesses, injuries, or malnutrition.

A 2014 STUDY,“PROTEIN INGESTION TO STIMULATE MYOFIBRILLAR PROTEIN SYNTHESIS REQUIRES GREATER RELATIVE PROTEIN INTAKES IN HEALTHY OLDER VERSUS YOUNGER MEN”. 

Concluded that MPS reached a plateau in younger men (early 20s) with a protein dose of 0.24 g/kg BW, while in older men (early 70s) MPS reached a plateau after ingestion of 0.40 g/kg BW.These are averages values.The upper 95% high-end limits are worth pointing out.

A 2020 RCT CROSSOVER STUDY,“THE ANABOLIC RESPONSE TO DIETARY PROTEIN IS NOT LIMITED BY THE MAXIMAL STIMULATION OF PROTEIN SYNTHESIS IN HEALTHY OLDER ADULTS”. 

In older untrained adults ( age 69.3 years), 70 g protein from beef patties elicited greater MPS than 35 g.

NOTE:Mixed-macronutrient meal used.

A 2019 RCT STUDY,“DOSE-DEPENDENT INCREASES IN WHOLE-BODY NET PROTEIN BALANCE AND DIETARY PROTEIN-DERIVED AMINO ACID INCORPORATION INTO MYOFIBRILLAR PROTEIN DURING RECOVERY FROM RESISTANCE EXERCISE IN OLDER MEN”. 

#15, 30, AND 45 G MILK PROTEIN CONCENTRATE#POST-RESISTANCE EXERCISE#UNTRAINED OLDER(66 AGE) ADULTS.

whole-body protein synthesis was highest with the 45 g dose, MPS plateaued at 30 g.

A 2016 A SYSTEMATIC REVIEW STUDY,“DOES THE MUSCLE PROTEIN SYNTHETIC RESPONSE TO EXERCISE AND AMINO ACID-BASED NUTRITION DIMINISH WITH ADVANCING AGE?”. 

From 48 study groups,18 study groups showed evidence of age-related anabolic resistance, 30 study arms did not.

when resistance exercise and protein/amino acid-based nutrition were combined, only 2 of the 10 study arms showed age-related anabolic resistance.

Adolescents:The timeframe spanning from the beginning of puberty, to the beginning of adulthood(10–19 years of age, also been referred to as 12–18 years of age).

Infancy to early childhood is the first fast-growing Phase of human life.

Adolescence is the second fast-growing Phase of human life.

Adolescent athletes should consume 1.2-2.0 g/kg, which reflects the most recent joint position stand of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine.

FINAL THOUGHTS

• Anabolic resistance linked to age actually demands that the protein intake is increased with advancing age, rather than decreased.
• In the general / untrained elderly, and especially in the weak elderly, there is anabolic resistance. However, this is not necessarily true for healthy older subjects, particularly those who combine resistance training and adequate protein feeding.

No.

Protein restriction is a well-studied tool for promoting longevity in animal models, but it is not based on human research.

The single-celled fungus Saccharomyces Cervidae, also known as brewer’s yeast, has been shown to live longer with glucose and amino acid restriction.

Due to its short lifespan and easy trial repeatability, longevity experiments were carried out on yeast.Lifespan increases from amino acid or protein restriction have also been seen in flies, worms, and rodents.Animal data does not automatically apply to humans.

A 2014 OBSERVATIONAL STUDY,“LOW PROTEIN INTAKE IS ASSOCIATED WITH A MAJOR REDUCTION IN IGF-1, CANCER, AND OVERALL MORTALITY IN THE 65 AND YOUNGER BUT NOT OLDER POPULATION”.

• Moderate protein intakes (10-19% of calories from protein) and high-protein intakes (≥20% of calories from protein) had higher risks of diabetes-related death than the low protein intakes (<10% of calories from protein) group.
• Aged 50–65 years, higher protein intakes increased risks of all-cause & cancer-related death.
• Aged 66 years and older, the high-protein intakes were associated with the opposite effect,  lower all-cause and cancer-related death.

NOTE: These two-way results are based on observational data. The majority of their findings were based on a single 24-hour dietary recall, followed up by as much as 18 years of mortality assessment.

FINAL THOUGHTS

Protein restriction benefits are derived from animal data, the results of which differ largely from controlled human data.

No.

No leading scientific institution has set the differing protein requirements for men and women in the history of official dietary recommendations.

A 2001 REVIEW STUDY,“GENDER DIFFERENCES IN PROTEIN METABOLISM”. 

Studies in the late- 1990s and early 2000s showing that between the sexes, there are no differences in whole-body protein synthesis or breakdown, and no difference in basal level of net muscle protein balance.

Q: Would it be possible to enhance muscle growth by reducing the number of feedings?

A: Yes, it’s possible this is the gray areas of research with room for more investigation.

A 2002, “EFFECT OF HIGH-FAT, HIGH-CARBOHYDRATE, AND HIGH-PROTEIN MEALS ON METABOLISM AND PERFORMANCE DURING ENDURANCE CYCLING.”

12 elite cyclists ate either a high-fat, high-carbohydrate, or high-protein meal 90 minutes before a sprinting and 50-KM performance test. 

There were no significant differences in performance across the treatments compared.

NOTE:There is no study specifically comparing pre-exercise protein with other macronutrients for strength performance.

A 2008 RCT, “HUMAN INSULINOTROPIC RESPONSE TO ORAL INGESTION OF NATIVE AND HYDROLYSED WHEY PROTEIN.”

• when 45 grams of whey is ingested alone, it takes about 45 minutes for circulating amino acid levels to peak, and another 2 hours to return to baseline levels.
• Start of the intense activity, pre-workout nutrition can function as intra workout nutrition. 

A 2006 RCT, “LIQUID CARBOHYDRATE/ESSENTIAL AMINO ACID INGESTION DURING A SHORT-TERM BOUT OF RESISTANCE EXERCISE, SUPPRESSES MYOFIBRILLAR PROTEIN DEGRADATION.”

• A beverage containing carbohydrate + essential amino acids suppressed Muscle Protein Breakdown.
• Intra workout protein intake only applies to fasted resistance training.

Q: Protein taken before exercise results in greater increases in energy expenditure compared to carbohydrate.?

A: Yes.it’s possible this is the gray areas of research.

A 2010 DOUBLE-BLIND TWO-TRIAL CROSSOVER DESIGN STUDY,“TIMING PROTEIN INTAKE INCREASES ENERGY EXPENDITURE 24 H AFTER RESISTANCE TRAINING”.

At 24 h after Heavy Resistance Training, Resting Energy Expenditure in response to PRO was significantly greater compared with CHO.

A 2015 RANDOMIZED, CROSSOVER, DOUBLE-BLIND STUDY,“THE ACUTE EFFECT OF EXERCISE MODALITY AND NUTRITION MANIPULATIONS ON POST-EXERCISE RESTING ENERGY EXPENDITURE AND RESPIRATORY EXCHANGE RATIO IN WOMEN”.

Pre-exercise PRO ingestion increased post-exercise Resting Energy Expenditure (REE) & decreased post-exercise respiratory exchange ratio compared to pre-exercise CHO ingestion.

A 2018 PILOT STUDY, “METABOLIC IMPACT OF PROTEIN FEEDING Before MODERATE-INTENSITY TREADMILL EXERCISE IN A FASTED STATE:”

• Protein consumption before fasted moderate-intensity treadmill exercise significantly  improved  Post-exercise fat oxidation.
• Casein protein allowed for more fat oxidation than whey.

NOTE:Short-term differences in energy expenditure don’t guarantee advantages in body composition change over the longer-term.

A 2017 STUDY, “PRE- VERSUS POST-EXERCISE PROTEIN INTAKE HAS SIMILAR EFFECTS ON MUSCULAR ADAPTATIONS.”

Direct comparison of pre-versus post-exercise protein intake failed to show any meaningful body composition advantage to either protocol.

A 2010 A RANDOMIZED CROSSOVER STUDY, “INCREASED P70S6K PHOSPHORYLATION DURING INTAKE OF A PROTEIN-CARBOHYDRATE DRINK FOLLOWING RESISTANCE EXERCISE IN THE FASTED STATE.”

Found a greater anabolic signalling response to the post-exercise meal after fasted exercise, compared to exercise in fed conditions.