Topic
Nutrition & Protein
Research on protein requirements, timing and diet composition — including myths like 'high protein harms kidneys'.
Research
Related research
- Randomized controlled trialConfidence: Moderate2014
Alcohol Ingestion Impairs Maximal Post-Exercise Rates of Myofibrillar Protein Synthesis following a Single Bout of Concurrent Training
Parr EB, Camera DM, Areta JL, Burke LM, Phillips SM, Hawley JA, Coffey VG / PLOS ONE
Key point: トレーニング後のアルコール摂取（1.5g/kg体重相当）は筋線維タンパク質合成を最大24%抑制した
- Randomized controlled trialConfidence: Moderate2015
Food Order Has a Significant Impact on Postprandial Glucose and Insulin Levels
Shukla AP, Iliescu RG, Thomas CE, Aronne LJ / Diabetes Care
Key point: 野菜・タンパク質・脂質先食い群は炭水化物先食い群と比較して食後30分・60分の血糖値が有意に低かった
- ReviewConfidence: Moderate2015
Effects of intermittent fasting on body composition and clinical health markers in humans
Tinsley GM, La Bounty PM / Nutrition Reviews
Key point: 16〜24時間の断食では、タンパク質摂取量が確保されていれば顕著な筋タンパク質分解は起きにくい
- Randomized controlled trialConfidence: Moderate2009
Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men
Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA, Phillips SM / Journal of Applied Physiology
Key point: ホエイはカゼイン・ソイと比較してレジスタンス運動後の筋タンパク質合成を有意に高めた
- ReviewConfidence: Moderate2016
B vitamins and energy metabolism: roles, deficiencies, and supplementation effects — a review
Kennedy DO / Nutrients
Key point: B vitamins are essential cofactors in ATP production, the TCA cycle, and fatty acid β-oxidation
- Meta-analysisConfidence: High2014
Iron Deficiency and Aerobic Exercise Performance: A Systematic Review and Meta-analysis
Pasricha SR, et al. / British Journal of Haematology
Key point: Iron supplementation improved VO2max by an average of +3.9 ml/kg/min (95% CI: 1.9–5.9)
- Meta-analysisConfidence: Moderate2016
Effects of L-Carnitine Supplementation on Fat Metabolism, Exercise Performance, and Body Composition: A Meta-Analysis
Pooyandjoo M, et al. / Obesity Reviews
Key point: Significant but small reduction in body weight vs placebo
- Randomized controlled trialConfidence: Moderate1996
Effects of Zinc Supplementation on Testosterone Levels and Immune Function
Prasad AS, et al. / Nutrition
Key point: In zinc-deficient older men, testosterone approximately doubled with supplementation (recovery within normal range)
- ReviewConfidence: Moderate2017
Branched-chain amino acids and muscle protein synthesis in humans: myth or reality?
Wolfe RR / Journal of the International Society of Sports Nutrition
Key point: BCAA alone can theoretically stimulate MPS by up to ~30%, but missing EAAs limit actual anabolic impact
- Meta-analysisConfidence: High2018
Protein supplementation augments resistance-training-induced gains in muscle mass and strength (meta-analysis)
Morton RW, et al. / British Journal of Sports Medicine
Key point: Protein adds to lean-mass and strength gains
Supplements
Related supplements
Casein Protein
Confidence: HighCasein (Micellar Casein / Calcium Caseinate)
Casein protein is a milk-derived protein characterized by slow digestion and absorption over 6 to 8 hours. Research suggests that pre-sleep casein intake may enhance muscle protein synthesis overnight. Combining casein with whey protein is thought to optimize both immediate and prolonged amino acid delivery.
Soy Protein
Confidence: ModerateSoy protein (isolate / concentrate)
A plant-based complete protein containing all nine essential amino acids, studied as a practical option for those with dairy allergies or following a vegan diet. Leucine content is somewhat lower than whey, which may result in a slightly smaller muscle protein synthesis response, but research suggests it is a useful tool for meeting total daily protein targets.
Vitamin B Complex
Confidence: ModerateB vitamins (B1, B2, B3, B5, B6, B7, B9, B12)
A collective term for eight B vitamins. Reviews describe each as an essential coenzyme in mitochondrial ATP production, the TCA cycle, fatty-acid β-oxidation, and amino-acid metabolism. Deficiency causes neurological symptoms, dermatitis, or anemia, but added benefit for already-replete healthy people is limited. Being water-soluble, excess is excreted and toxicity risk at usual doses is low.
Vitamin B-50
Confidence: ModerateB vitamins balanced at around 50 mg/µg each
A higher-dose formula that balances the B vitamins at roughly 50 mg/µg each. The underlying roles (coenzymes in energy metabolism) are based on the same review. Supplementation is meaningful for deficient people, while added benefit for the replete is limited. Because each component is dosed high, upper-limit awareness matters more.
Whey Protein
Confidence: HighWhey protein
A convenient way to top up protein that's hard to hit through meals alone. Rich in leucine, which helps trigger muscle protein synthesis. A supplement to total intake — not a magic powder.
Articles
Related reads
- Research vs Bro-science
Does Drinking Alcohol Really Not Affect Muscle Growth or Fat Loss? The Casual Drinking Myth vs. Research
"A few drinks on the weekend won't hurt my gains" — convenient thinking about alcohol and training is common. What does the research actually show about alcohol's impact on muscle protein synthesis and fat loss?
Shingo Yoshizaki
- Research vs Bro-science
Does Eating Vegetables First Really Lower Blood Sugar Spikes? Food Order vs. Research
"Eat your vegetables first to avoid blood sugar spikes" — a staple of healthy-eating culture. How real is the effect, and does blood sugar control from food order actually impact long-term weight or muscle building?
Shingo Yoshizaki
- Research vs Bro-science
Can Protein Bars Replace Meals? The Processed Protein Myth vs. Research
Convenient, portable, high-protein — protein bars seem like the perfect meal replacement. But regularly substituting them for meals raises real concerns about nutritional quality and food processing.
Shingo Yoshizaki
- Research vs Bro-science
Do Carbs at Night Make You Fat? Common Belief vs. the Evidence
The idea that eating carbs at night leads to fat gain is treated as settled wisdom in diet culture. Many people cut back on dinner rice or pasta as a direct result. But what does the research actually say?
Shingo Yoshizaki
- Research vs Bro-science
Can a Cheat Day Break a Weight Loss Plateau? Common Wisdom vs. Research
When weight loss stalls, the idea that a cheat day 'resets your metabolism' is widely embraced in training communities. But research draws a different picture between a single day of overfeeding and a more structured 'diet break' approach.
Shingo Yoshizaki
- Research vs Bro-science
Is Eating as Much as Possible Really the Best Way to Bulk?
The idea that eating as much as possible during a bulk leads to maximum muscle growth is a long-standing gym belief. Yet research suggests that excessive calorie surpluses tend to add fat more than muscle. This article examines three key claims behind dirty bulking through the lens of current evidence.
Shingo Yoshizaki
- Research vs Bro-science
Does a Higher Price Tag Mean Better Protein? Common Wisdom vs. the Research
"Cheap protein is inferior and expensive protein builds more muscle" is a claim that circulates freely in gyms and supplement reviews. But does price actually correlate with hypertrophy outcomes? We examine three angles — including whey type differences — through the lens of the research.
Shingo Yoshizaki
- Research vs Bro-science
Does IIFYM Really Work? 'If It Fits Your Macros' vs. The Research
"Hit your macros and eat whatever you want" — IIFYM (If It Fits Your Macros) is a popular flexible dieting approach in the fitness community. It promises freedom from food guilt while still meeting body composition goals. But does ignoring food quality really matter? Here's what the research says.
Shingo Yoshizaki
- Research vs Bro-science
Does Eating More Often Boost Your Metabolism? Common Belief vs. Research
The idea that eating 5–6 smaller meals a day revs up your metabolism is everywhere in fitness culture. But what does the actual research say? We examine this claim through three lenses: thermic effect of food, body composition, and metabolic adaptation.
Shingo Yoshizaki
- Research vs Bro-science
Do You Really Need 2g of Protein per kg of Bodyweight? Common Wisdom vs. the Research
"Eat 2g of protein per kg of bodyweight" is one of the most repeated nutrition rules in any gym. But does the science actually back that number, or is it overcautious bro-math? We put the claim through three rounds against the meta-analytic evidence.
Shingo Yoshizaki
- Research vs Bro-science
Should You Eat More Protein While Cutting? Common Wisdom vs. the Research
"Eat more protein while cutting or you'll lose muscle" is a constant refrain in gyms and fitness content. We test this claim from three angles — optimal protein intake under caloric restriction, the impact of cutting speed, and whether protein source type matters — against what the research actually shows.
Shingo Yoshizaki
- Explainer
Do You Need Iron Supplements? Evidence on Iron Deficiency and Exercise Performance
When iron is deficient, supplementation improves VO2max by an average of +3.9 ml/kg/min. Even latent iron deficiency without anemia reduces endurance, so regular iron status monitoring is valuable—particularly for menstruating women, endurance athletes, and vegetarians. However, supplementation in iron-sufficient individuals is not expected to be beneficial, and excess intake carries risks.
Shingo Yoshizaki
- Explainer
What is L-Carnitine? The fat transporter's real potential — and its limits
L-carnitine is an amino acid derivative that transports fatty acids into mitochondria for energy production. A meta-analysis of 9 RCTs found statistically significant but small reductions in body weight and BMI compared with placebo, with effects appearing conditional on caloric restriction or exercise. Research does not support dramatic fat loss from L-carnitine alone.
Shingo Yoshizaki
- Research vs Bro-science
Does more protein always mean more muscle? Lore vs research
'In a bulk, just eat tons of protein — the more you take, the more muscle you build.' We test this gym staple against the research on dose–response, the role of training, and age.
Hirotsugu Yoshimura
- Explainer
Vitamin B complex basics: cofactors in energy metabolism and deficiency conditions
B vitamins are indispensable cofactors in ATP production, the TCA cycle, and fatty acid metabolism. Deficiency causes neurological symptoms, dermatitis, and anemia. Research shows clear benefit of supplementation in deficient individuals, while additional effects in already-replete healthy people are limited.
Shingo Yoshizaki
- Explainer
What is vitamin B50? The balanced-formula B complex and when to use it
Vitamin B50 is a formula containing each B vitamin (B1, B2, B3, B6, B12, etc.) at an equal dose of 50 mg or 50 mcg. Research shows that B vitamin supplementation has clear benefits for deficient individuals—improving neurological symptoms, dermatitis, and anemia—but additional effects in already-replete healthy people are limited.
Shingo Yoshizaki
- Explainer
Zinc Supplements: Evidence on Immunity, Testosterone, and Muscle—and What to Watch Out For
When zinc is deficient, supplementation has been shown to improve immune function and restore testosterone to normal levels. However, additional supplementation does not raise testosterone in those who are already zinc-sufficient. Checking deficiency status before supplementing is the rational approach.
Shingo Yoshizaki
- Research vs Bro-science
Does BCAA Actually Work? The Evidence on Muscle Growth and Recovery
BCAA supplements have been a staple for gym-goers for decades. Claims like 'prevent muscle breakdown' and 'speed up recovery' are repeated as common knowledge in training communities. But the research picture looks quite different from the marketing.
Shingo Yoshizaki
- Research vs Bro-science
Does high protein wreck your kidneys? Lore vs research
Gyms and the internet keep repeating that 'too much protein damages your kidneys.' How true is it for healthy people? We line up the claims against the research.
Hirotsugu Yoshimura