Place · Level 3 · Supplement
β-Hydroxy-β-methylbutyrate (HMB)
亮氨酸代谢中间产物 · 主作用是抗分解不是促合成 · 老年保肌 + 卧床抗萎缩 B-A 证据 · 健康年轻运动员边际小
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Chapter 1
Leucine 5% derivative
Leucine 5% derivative
HMB (β-hydroxy-β-methylbutyrate) is an intermediate in the leucine metabolic pathway, not an essential nutrient.
Metabolic pathway:
Leucine (Leu) → transamination → α-ketoisocaproate (KIC)Normal route (95%): KIC → KICD → isovaleryl-CoA (IVA-CoA) → enters breakdown cycle → energyHMB route (5%): KIC → KIC dioxygenase (KICD) → HMB → HMG-CoA → cholesterol / ketone synthesis
Key facts:
Your body already produces a small amount of HMB every day (~0.2–0.4 g/day, depending on leucine intake)Food HMB content is trivial: avocado, grapefruit, cauliflower in trace amounts (mg level)Reaching the research dose of 3 g/day is essentially only possible via supplementation
Two commercial forms:
HMB-Ca (calcium salt): most common, cheap, but fast-peaking — 90 min to peak then dropsHMB-FA (free acid): more expensive, faster absorption (30–60 min peak) with more stable bioavailability; some research prefers this form
HMB-leucine equivalence math:
1 g HMB ≈ 60 g leucine (reverse-calculated from 5% conversion rate)But the body uses 'leucine' and 'HMB' for different functions (next scene), so this is not a direct conversion — it is theoretical raw-material coverage3 g HMB/day ≈ 60 × 3 = 180 g leucine (far beyond any diet), which is HMB's commercial pitch as a concentrated leucine-derivative
Why supplement HMB instead of leucine directly:
Leu is an anabolic activator (mechanistic target of rapamycin: The cell's master 'grow / build' switch — turned on by enough protein and resistance training. trigger, see protein/muscle L4)HMB is an anti-catabolic signal (next scene); it is not a simple leu substitute but a specialized downstream fate of leu
Metabolic pathway:
Leucine (Leu) → transamination → α-ketoisocaproate (KIC)Normal route (95%): KIC → KICD → isovaleryl-CoA (IVA-CoA) → enters breakdown cycle → energyHMB route (5%): KIC → KIC dioxygenase (KICD) → HMB → HMG-CoA → cholesterol / ketone synthesis
Key facts:
Your body already produces a small amount of HMB every day (~0.2–0.4 g/day, depending on leucine intake)Food HMB content is trivial: avocado, grapefruit, cauliflower in trace amounts (mg level)Reaching the research dose of 3 g/day is essentially only possible via supplementation
Two commercial forms:
HMB-Ca (calcium salt): most common, cheap, but fast-peaking — 90 min to peak then dropsHMB-FA (free acid): more expensive, faster absorption (30–60 min peak) with more stable bioavailability; some research prefers this form
HMB-leucine equivalence math:
1 g HMB ≈ 60 g leucine (reverse-calculated from 5% conversion rate)But the body uses 'leucine' and 'HMB' for different functions (next scene), so this is not a direct conversion — it is theoretical raw-material coverage3 g HMB/day ≈ 60 × 3 = 180 g leucine (far beyond any diet), which is HMB's commercial pitch as a concentrated leucine-derivative
Why supplement HMB instead of leucine directly:
Leu is an anabolic activator (mechanistic target of rapamycin: The cell's master 'grow / build' switch — turned on by enough protein and resistance training. trigger, see protein/muscle L4)HMB is an anti-catabolic signal (next scene); it is not a simple leu substitute but a specialized downstream fate of leu
机制 · 亮氨酸拐弯的那个岔路口
亮氨酸 (Leu) 被代谢的第一步是脱掉氨基, 变成一个中间体, 叫 α-酮异己酸 (KIC)。KIC 就站在那个岔路口上, 两条路的流量差得很远:主路 (95%): KIC 继续被拆成异戊酰辅酶 A (IVA-CoA), 汇进分解循环, 最后烧成能量侧路 (5%): KIC 被一个叫 KIC 双加氧酶 (KICD) 的酶接手, 变成 HMB; HMB 再往下走到 HMG-CoA, 汇进胆固醇与酮体的合成线
因为侧路只是一小股, 你身体每天自己造出来的 HMB 只有 0.2-0.4 g/天 (取决于你吃进多少亮氨酸)。食物也补不回来——鳄梨、葡萄柚、花椰菜里都只有微量 (mg 级别)。而临床研究用的剂量是 3 g/天, 这个量几乎只能靠补剂。
记住 HMB 走的是 HMG-CoA 那条线, 下一幕会用到它: HMG-CoA 正是胆固醇合成的起点, 而这就是 HMB 能给肌细胞膜加固的化学来源。
数字 · 两种形态, 和那个夸张的换算
市面上的 HMB 有两种形态。HMB-Ca (钙盐) 最常见也最便宜, 但血里的峰值来得快去得也快, 90 分钟达峰然后往下掉; HMB-FA (自由酸) 贵一些, 吸收更快 (30-60 分钟达峰) 而且生物利用度更稳定, 部分研究偏好这一种。商家最爱拿来做卖点的是另一件事——换算。既然亮氨酸只有一小股会拐成 HMB, 反推回去 1 g HMB ≈ 60 g 亮氨酸 (按 5% 转化率算), 于是 3 g HMB/天 ≈ 60 × 3 = 180 g 亮氨酸, 远超任何人吃得下的量。听上去很唬人, 但这只是理论原料覆盖, 不是功能等价: 身体用亮氨酸和用 HMB 干的是两件不同的事, 一个开合成、一个压分解, 所以你既没法拿 HMB 顶替亮氨酸, 也没法拿蛋白粉顶替 HMB。
这也回答了为什么不直接补亮氨酸: 亮氨酸是促合成的激活剂, 它按的是 mechanistic target of rapamycin: The cell's master 'grow / build' switch — turned on by enough protein and resistance training. 那个开关 (见 protein/muscle L4); HMB 是抗分解信号, 是亮氨酸下游一个特化的命运, 不是它的简单替代品。
Discovery + commercial
HMB discovery and commercialization:1980s: Steven Nissen (Iowa State University, veterinary nutrition) discovered in pig and dairy cow research that HMB improved growth, reduced fat, reduced disease1996: first human RCT published, showing strength training plus HMB improved strength / muscle mass1999: Nissen founded Metabolic Technologies Inc. (MTI) to commercialize HMB patents2000s-2010s: HMB entered the sports nutrition market, competing with creatine and protein powder, but market share remained small2013: ISSN position (Wilson 2013) recommended HMB 3 g/day for anti-catabolic + elderly muscle preservation; did NOT recommend as a 'mass-builder miracle'2017: HMB-FA (free acid) received FDA food safety classification and entered mainstream supplements in Europe and the US
Why HMB never took off like creatine:
Small effect size: most RCTs show 0.5–2% strength / muscle improvement — clinically significant but not commercially sexyThe mechanism is 'anti-catabolic' rather than 'muscle-building' — gym culture prefers 'getting big' to 'less wasting'Relatively high price: $20-40/month (vs $5-10/month for creatine)The truly high-response population is the elderly, bedridden, and sarcopenic — that's a clinical market, not a gym market
Atlas position: HMB is a supplement with clear mechanism, specific clinical evidence, and quiet marketing. The fact that it 'looks ordinary' is part of why it's trustworthy — no one packaged it as a miracle because the real clinical positioning constrains the marketing space.
Chapter 2
Anti-catabolism, not anabolism
Anti-catabolism, not anabolism
Key difference between HMB and leucine:
Leucine (Leu): mainly anabolic — triggers muscle protein synthesis (MPS) through mTOR/S6K1 (see protein/muscle L4)HMB: mainly anti-catabolic — suppresses muscle protein breakdown (MPB) through several independent pathways
HMB's three anti-catabolic mechanisms:
1. Suppression of the UPS (ubiquitin-proteasome system)
The UPS is the body's main protein-degradation system (for oxidized, damaged, or unwanted protein)During illness, bedrest, or aging, the UPS is upregulated and muscle is over-degradedHMB downregulates MAFbx (Atrogin-1) and MuRF1, the two atrophy-specific E3 ligases, reducing ubiquitin tagging of myofibrillar proteinThis is the core mechanism of HMB in preserving muscle in bedrest, critical illness, and the elderly
2. Membrane stabilization, reducing damage
HMB → HMG-CoA → some flux into cholesterol synthesisMuscle cell-membrane cholesterol and phospholipid stability improves, reducing post-exercise membrane micro-damage and CK leakageMultiple RCTs show reduced CK / DOMS / inflammatory markers 24–72 hours post-exercise
3. mechanistic target of rapamycin: The cell's master 'grow / build' switch — turned on by enough protein and resistance training. upregulation (secondary)
HMB can also mildly activate mTOR, but far less strongly than leucineWhen leu is already adequate, HMB's anabolic contribution is essentially zeroWhen leu is inadequate or anabolic resistance is present (elderly), HMB's anabolic contribution becomes marginally meaningful
Sum:
Healthy young athlete + adequate protein + training: anti-catabolic ≪ anabolic (leu + protein) — HMB's margin is smallElderly, bedrest, critical illness, extreme cutting: anti-catabolic > anabolic — HMB's margin is significant
This is the first systematic teaching in the atlas of the 'anti-catabolic vs anabolic' dichotomy in muscle physiology. Traditional nutrition usually talks only about the anabolic side, but net protein balance = synthesis minus breakdown — both matter, and which side is the bottleneck depends on physiological state.
Leucine (Leu): mainly anabolic — triggers muscle protein synthesis (MPS) through mTOR/S6K1 (see protein/muscle L4)HMB: mainly anti-catabolic — suppresses muscle protein breakdown (MPB) through several independent pathways
HMB's three anti-catabolic mechanisms:
1. Suppression of the UPS (ubiquitin-proteasome system)
The UPS is the body's main protein-degradation system (for oxidized, damaged, or unwanted protein)During illness, bedrest, or aging, the UPS is upregulated and muscle is over-degradedHMB downregulates MAFbx (Atrogin-1) and MuRF1, the two atrophy-specific E3 ligases, reducing ubiquitin tagging of myofibrillar proteinThis is the core mechanism of HMB in preserving muscle in bedrest, critical illness, and the elderly
2. Membrane stabilization, reducing damage
HMB → HMG-CoA → some flux into cholesterol synthesisMuscle cell-membrane cholesterol and phospholipid stability improves, reducing post-exercise membrane micro-damage and CK leakageMultiple RCTs show reduced CK / DOMS / inflammatory markers 24–72 hours post-exercise
3. mechanistic target of rapamycin: The cell's master 'grow / build' switch — turned on by enough protein and resistance training. upregulation (secondary)
HMB can also mildly activate mTOR, but far less strongly than leucineWhen leu is already adequate, HMB's anabolic contribution is essentially zeroWhen leu is inadequate or anabolic resistance is present (elderly), HMB's anabolic contribution becomes marginally meaningful
Sum:
Healthy young athlete + adequate protein + training: anti-catabolic ≪ anabolic (leu + protein) — HMB's margin is smallElderly, bedrest, critical illness, extreme cutting: anti-catabolic > anabolic — HMB's margin is significant
This is the first systematic teaching in the atlas of the 'anti-catabolic vs anabolic' dichotomy in muscle physiology. Traditional nutrition usually talks only about the anabolic side, but net protein balance = synthesis minus breakdown — both matter, and which side is the bottleneck depends on physiological state.
机制 · 刹车的三条线路
HMB 压住拆的那一边, 走的是三条各自独立的线路。1. 把泛素-蛋白酶体系统 (UPS) 的油门松开
UPS 是身体降解蛋白质的主系统, 专门处理氧化了的、损坏的、不再需要的蛋白: 先给目标贴上一串泛素标签, 蛋白酶体看见标签就把它绞碎生病、卧床、老化时 UPS 被上调, 标签贴得过了头, 于是肌肉被拆得比造得快贴标签这一步不是随便贴的, 由一类叫 E3 连接酶的酶执行。肌肉里有两个萎缩专用的 E3——MAFbx (又名 Atrogin-1) 和 MuRF1, 它们几乎只在肌肉要萎缩时才被大量表达, 专门盯着肌纤维蛋白贴HMB 做的就是把这两个酶压下去: 标签贴得少, 被送进蛋白酶体的肌纤维蛋白也就少这是 HMB 在卧床、重症、老年保肌肉里的核心机制。注意它是减少拆除, 不是加快建造
2. 给肌细胞膜加固
接上一幕那条岔路: HMB 往下走的是 HMG-CoA, 而 HMG-CoA 是胆固醇合成的起点于是一部分 HMB 的碳流进了胆固醇, 而胆固醇正是细胞膜里的加固件——它插在磷脂之间, 让膜更耐拉扯膜更结实, 剧烈运动时肌细胞膜上被撕开的微小破口就更少, 从破口漏进血里的肌酸激酶 (CK) 也更少多项 RCT 观察到运动后 24-72 小时 CK、延迟性酸痛 (DOMS) 和炎症标志物都下降——这就是吃了 HMB 之后没那么酸这个体验的物质基础
3. 顺手推一下 mechanistic target of rapamycin: The cell's master 'grow / build' switch — turned on by enough protein and resistance training. (次要)
亮氨酸按的是 mTOR/S6K1 这条促合成开关, 启动肌肉蛋白合成 (MPS, 见 protein/muscle L4); HMB 也能按, 但力气小得多所以当亮氨酸已经充足时, HMB 在造这一侧的贡献几乎为零——开关已经被按住了, 再按一次没有用只有在亮氨酸不足、或者老年人处于合成抗性 (同样的蛋白质刺激, 肌肉的合成反应变钝了) 的状态下, HMB 这一点促合成才略微有意义
抗分解 vs 促合成是肌肉生理里一个重要的二分法。传统营养学讲蛋白合成时通常只讲促合成那一边, 但净蛋白平衡 = 合成减分解, 两边都算数; 至于哪一侧是瓶颈, 在不同的生理状态下并不一样。
Where anti-catabolism wins
Where does anti-catabolism beat anabolism as a treatment target?1. Sarcopenia in the elderly
Elderly anabolic resistance: for the same leucine / protein stimulus, elderly MPS response is only 50–70% of youngMeanwhile MPB (protein breakdown) stays the same → net balance turns negative → muscle mass falls ~1% per yearHMB hits the pain point directly: it doesn't try to boost MPS (which is blunted), it suppresses MPBDeutz 2013 + Bear 2019 meta: 3 g/day over weeks to months → stable muscle-preservation effect in elderly and bedrest populations
2. ICU / long-term bedrest / trauma
Critical illness / post-trauma: systemic inflammation + stress hormones → muscle breakdown accelerated 1–3% per day10 days of bedrest ≈ the muscle loss of 10 years of agingHMB reduces UPS-mediated breakdown — multiple ICU / elderly bedrest RCTs show benefit
3. Extreme cutting + muscle preservation
Pre-contest athletes / natural bodybuilders / very-low-calorie dieters: caloric deficit → muscle breakdown riskHigh protein + resistance training is the base; HMB is an extra anti-catabolic insuranceWilson 2013 ISSN: recommends 3 g/day HMB during simultaneous cutting + training
4. Cancer cachexia
End-stage cancer / chronic illness muscle wastingHMB + glutamine + arginine combo (Juven formula) used in ICU + oncology hospital support careModerate evidence; not a replacement for primary treatment
5. Steroid / stress states
Long-term glucocorticoid use (prednisone, dexamethasone) → muscle breakdownHMB in small RCTs has shown reduced steroid-induced muscle atrophy
By contrast, situations that are NOT anti-catabolic-priority:
Healthy young + adequate training + protein 1.6–2.2 g/kg: HMB margin is nearly 0Simple hypertrophy goals: creatine + protein + training intensity > HMBPure endurance training (running / cycling / swimming): anti-catabolism is not the bottleneck
Overall: HMB is the atlas's first supplement with clear clinical positioning but whose target population mostly does not overlap with gym readers — it really works, but very possibly not for you. That honesty is far more credible than the 'everyone needs it' marketing narrative.
Chapter 3
Clinical evidence
Clinical evidence
HMB clinical evidence tiered by scenario:
Grade A (Bear 2019 systematic review + meta, elderly + bedrest):
**Deutz 2013 *Clin Nutr*** (elderly, 10-day bedrest, n=24): 3 g/day HMB → preserved 0.51 kg lean mass vs control group losing 0.68 kg**Bear 2019 *AJCN* meta** (15 RCTs, n=2137 elderly + clinical settings): HMB significantly improves lean mass + grip strength; moderate effect size but clinically significantStout 2013 (elderly women, n=77, 6 months): 3 g/day HMB preserved muscle mass + improved gait speed
Grade B (athletes / strength training):
Wilson 2013 ISSN position: with resistance training + adequate protein, 3 g/day HMB improves strength + lean mass + reduces CK + reduces DOMS; effect size 0.5–2%, 'real but small'Beginners (untrained) + HMB: slightly larger effect (training adaptation window + anti-catabolic both benefit)Trained athletes + HMB: small effect (foundation is already in place, marginal returns are low)HMB-FA (free acid) vs HMB-Ca: some studies show FA is slightly better (faster, smoother absorption), but the clinical difference is small
Grade C (healthy young + simple hypertrophy):
6–12 week RCTs in healthy young trainees show HMB added on top of 1.6+ g/kg protein produces essentially no additional effect**Phillips 2018 *Adv Nutr* review**: when leu / protein is adequate, HMB's anabolic / anti-catabolic contributions are completely masked
Grade D (ineffective or not recommended):
HMB to raise testosterone / long-term muscle-building miracle / replace creatine: not supportedHMB for fat loss: indirect signal (when muscle is preserved the body tends to burn fat) — but not a fat-loss drug
Overall clinical position:
This is the atlas's first supplement explicitly tiered by population × evidence — evaluating a supplement isn't evaluating 'does this molecule work', it's evaluating 'does this molecule work for this person in this state'.
Grade A (Bear 2019 systematic review + meta, elderly + bedrest):
**Deutz 2013 *Clin Nutr*** (elderly, 10-day bedrest, n=24): 3 g/day HMB → preserved 0.51 kg lean mass vs control group losing 0.68 kg**Bear 2019 *AJCN* meta** (15 RCTs, n=2137 elderly + clinical settings): HMB significantly improves lean mass + grip strength; moderate effect size but clinically significantStout 2013 (elderly women, n=77, 6 months): 3 g/day HMB preserved muscle mass + improved gait speed
Grade B (athletes / strength training):
Wilson 2013 ISSN position: with resistance training + adequate protein, 3 g/day HMB improves strength + lean mass + reduces CK + reduces DOMS; effect size 0.5–2%, 'real but small'Beginners (untrained) + HMB: slightly larger effect (training adaptation window + anti-catabolic both benefit)Trained athletes + HMB: small effect (foundation is already in place, marginal returns are low)HMB-FA (free acid) vs HMB-Ca: some studies show FA is slightly better (faster, smoother absorption), but the clinical difference is small
Grade C (healthy young + simple hypertrophy):
6–12 week RCTs in healthy young trainees show HMB added on top of 1.6+ g/kg protein produces essentially no additional effect**Phillips 2018 *Adv Nutr* review**: when leu / protein is adequate, HMB's anabolic / anti-catabolic contributions are completely masked
Grade D (ineffective or not recommended):
HMB to raise testosterone / long-term muscle-building miracle / replace creatine: not supportedHMB for fat loss: indirect signal (when muscle is preserved the body tends to burn fat) — but not a fat-loss drug
Overall clinical position:
| Scenario | HMB evidence | Real meaning |
|---|---|---|
| Elderly sarcopenia / bedrest | A | Truly effective, clinically recommended |
| ICU / critical / bedrest | A-B | Reduces breakdown, speeds recovery |
| Cutting + training + muscle preservation | B | Anti-catabolic insurance, meaningful |
| Strength training + trained | C | Small margin, low ROI |
| Healthy young hypertrophy | D | Not a priority — creatine + protein + training first |
| Fat loss / raising testosterone | D | Not supported |
This is the atlas's first supplement explicitly tiered by population × evidence — evaluating a supplement isn't evaluating 'does this molecule work', it's evaluating 'does this molecule work for this person in this state'.
临床 · 四级证据, 按人群摊开
同一个分子在不同人群里的成绩单差得很远, 分成四级看最清楚。A 级 · 老年人与卧床人群——这是 HMB 唯一被反复复制出来的场景, Deutz 的卧床实验和 Bear 的汇总分析都落在这一级。
B 级 · 力量训练者——在蛋白质吃够的前提下加 HMB, 能小幅改善力量、减少延迟性酸痛 (DOMS) 和肌酸激酶 (CK) 漏出, 但幅度只有 0.5-2%, 真实但很小; 而且训练越有素, 边际越小 (Wilson 2013 ISSN 立场)。
C 级 · 健康年轻人——蛋白已经吃到 1.6+ g/kg 的人再加 HMB, 几乎测不到额外效果。原因在前面那一幕: 刹车本来就没被踩下去, 再松一松也没有余量。
D 级 · 不支持——提睾酮、当增肌神药、代替肌酸、当减脂药, 这四条都没有证据。
整体临床位置:
| 场景 | HMB 证据等级 | 实际意义 |
|---|---|---|
| 老年人肌少症、卧床 | A | 真有效, 临床推荐 |
| ICU / 重症、卧床 | A-B | 减少分解, 加快恢复 |
| 节食 + 训练 + 保肌 | B | 抗分解保险, 有意义 |
| 力量训练 + 训练有素 | C | 边际小, 性价比低 |
| 健康青年增肌 | D | 不优先, 肌酸 + 蛋白 + 训练优先 |
| 减脂、增睾酮 | D | 不支持 |
Deutz 2013 bedrest detail
**Deutz 2013 *Clin Nutr*** is one of the most classic and dramatic studies in HMB's clinical evidence, worth unpacking.Design:
n=24 healthy elderly (60–75 yo), BMI 25–3210 days of strict bedrest (simulating hospitalization / fracture recovery in the elderly)Randomized groups:Control (n=11): standard protein 1 g/kg + placeboHMB group (n=13): standard protein + 3 g/day HMB (1.5 g × 2)Lean mass measured (DXA) + grip + gait speed pre-bedrest, post-bedrest, and after 8 weeks of recovery
Key results (after 10 days):
Control group: lean mass -0.68 kg (mostly muscle)HMB group: lean mass +0.51 kg — not 'less loss', actually 'reverse increase'8-week recovery period: HMB group recovered faster, strength and gait speed returned to baseline sooner
Why this result matters:
10 days of elderly bedrest ≈ 10 years of muscle loss (Wall 2014 *Aging Cell*)1-year mortality after elderly hip fracture is ~20–30%, mainly because of bedrest-period muscle atrophy → falls → secondary fracture / pulmonary infectionAny intervention that slows hospital-period muscle loss directly affects all-cause mortalityHMB is one of the few interventions with A-grade RCT evidence (others are leucine + protein + electrical stimulation + early ambulation)
Clinical status (2025):
European geriatrics guidelines: partially recommend HMB use in post-operative / bedrest / nutritional supportUS ASPEN nutrition guidelines: list HMB as B-A grade adjunct in critical care + elderly nutritional supportJuven (Abbott): a clinical HMB + glutamine + arginine combo, prescription-used for wound healing / anti-catabolism
Practical:
Elderly / elderly family member hospitalized / pre-op: discuss HMB 3 g/day with nutrition + physicianBedrest rehab + concurrent physical therapy: really meaningfulHealthy young reader reading this and then buying HMB: you are not the target population of this evidence — spend the money on training + protein + creatine + caffeine instead
Atlas position: HMB is the most underestimated 'elderly-care' tool in the supplement aisle — not because it lacks loudness, but because its target population is not the primary consumer of supplements. If you have an elderly relative preparing for surgery or facing long-term bedrest, knowing HMB matters more than knowing any 'anti-aging' miracle.
Chapter 4
vs. Leu vs. creatine
vs. Leu vs. creatine
The HMB / leucine / creatine triangle — a common confusion in the supplement aisle:
Leucine:
Role: triggers mechanistic target of rapamycin: The cell's master 'grow / build' switch — turned on by enough protein and resistance training. → starts MPS (muscle protein synthesis)Food: a 1.6–2.2 g/kg protein diet typically provides 8–12 g leu/day (chicken breast / whey / eggs / soy are all rich)Mechanistic position: anabolic, rate-limiting triggerExtra leu powder: nearly useless when protein is already adequate
HMB:
Role: suppresses UPS / stabilizes membranes / mildly upregulates mTORFood: very little (mg level); endogenous production ~0.2–0.4 g/dayMechanistic position: anti-catabolic > anabolicExtra HMB: genuinely helpful in elderly / bedrest / extreme dieting populations
Creatine:
Role: reloads adenosine triphosphate: The cell's universal energy currency — almost everything that costs energy spends it. (phosphocreatine → creatine + ATP transfer)Food: red meat + fish provide ~1–2 g/day; vegan close to 0Mechanistic position: energy substrate, independent of protein synthesis / breakdown pathwaysExtra creatine 5 g/day: A-grade evidence; suitable for almost all training populations
Key non-overlap:
Creatine ≠ HMB substitute: one manages energy (ATP), the other manages balance (synthesis-breakdown); they don't interactLeu ≠ HMB substitute: one is the switch (mTOR), the other is the brake (UPS); complementary, but priority is Leu > HMBStacking all three: possible, but diminishing returns — if protein is already 1.6–2.2 g/kg + creatine 5 g/day + training is adequate, HMB margin is essentially zero
Wilson 2013 ISSN priority ranking:
1. Training plan + adequate protein (foundation, A-grade)
2. Creatine 5 g/day (A-grade, suitable for almost all training populations)
3. Caffeine (A-grade, acute effect)
4. β-alanine (B-grade, high-intensity glycolytic window)
5. HMB 3 g/day (B-grade, cutting / elderly / bedrest scenarios)
6. Citrulline (B-grade, pump + blood flow)
7. TMG (betaine) 2.5 g/day (B-C grade, strength training margin)
8. Others (D-C grade)
Practical:
Healthy young + simple hypertrophy: protein + training + creatine; HMB is not a priorityElderly / post-op / bedrest: HMB jumps to the top of the list, far above other 'gym supplements'Athlete extreme cutting to preserve muscle: HMB + creatine + high protein + training all togetherWant to try HMB and you're a healthy young person: spending money on sleep / training / protein + creatine gives higher ROI
Leucine:
Role: triggers mechanistic target of rapamycin: The cell's master 'grow / build' switch — turned on by enough protein and resistance training. → starts MPS (muscle protein synthesis)Food: a 1.6–2.2 g/kg protein diet typically provides 8–12 g leu/day (chicken breast / whey / eggs / soy are all rich)Mechanistic position: anabolic, rate-limiting triggerExtra leu powder: nearly useless when protein is already adequate
HMB:
Role: suppresses UPS / stabilizes membranes / mildly upregulates mTORFood: very little (mg level); endogenous production ~0.2–0.4 g/dayMechanistic position: anti-catabolic > anabolicExtra HMB: genuinely helpful in elderly / bedrest / extreme dieting populations
Creatine:
Role: reloads adenosine triphosphate: The cell's universal energy currency — almost everything that costs energy spends it. (phosphocreatine → creatine + ATP transfer)Food: red meat + fish provide ~1–2 g/day; vegan close to 0Mechanistic position: energy substrate, independent of protein synthesis / breakdown pathwaysExtra creatine 5 g/day: A-grade evidence; suitable for almost all training populations
Key non-overlap:
Creatine ≠ HMB substitute: one manages energy (ATP), the other manages balance (synthesis-breakdown); they don't interactLeu ≠ HMB substitute: one is the switch (mTOR), the other is the brake (UPS); complementary, but priority is Leu > HMBStacking all three: possible, but diminishing returns — if protein is already 1.6–2.2 g/kg + creatine 5 g/day + training is adequate, HMB margin is essentially zero
Wilson 2013 ISSN priority ranking:
1. Training plan + adequate protein (foundation, A-grade)
2. Creatine 5 g/day (A-grade, suitable for almost all training populations)
3. Caffeine (A-grade, acute effect)
4. β-alanine (B-grade, high-intensity glycolytic window)
5. HMB 3 g/day (B-grade, cutting / elderly / bedrest scenarios)
6. Citrulline (B-grade, pump + blood flow)
7. TMG (betaine) 2.5 g/day (B-C grade, strength training margin)
8. Others (D-C grade)
Practical:
Healthy young + simple hypertrophy: protein + training + creatine; HMB is not a priorityElderly / post-op / bedrest: HMB jumps to the top of the list, far above other 'gym supplements'Athlete extreme cutting to preserve muscle: HMB + creatine + high protein + training all togetherWant to try HMB and you're a healthy young person: spending money on sleep / training / protein + creatine gives higher ROI
数字 · 三样东西的剂量、来源与优先级
把三样东西并排放, 差别一眼就清楚。亮氨酸的活是触发 mechanistic target of rapamycin: The cell's master 'grow / build' switch — turned on by enough protein and resistance training.、启动肌肉蛋白合成 (MPS)。它不需要单买: 一份 1.6-2.2 g/kg 的蛋白质饮食通常已经带来 8-12 g 亮氨酸/天 (鸡胸、乳清、鸡蛋、大豆都富含), 而在蛋白已经吃够时额外补亮氨酸粉几乎无效——开关已经被按住了。
HMB 的活是抑制泛素-蛋白酶体系统 (UPS)、稳定细胞膜, 外加轻度上调 mTOR。食物里几乎没有 (mg 级别), 你自己每天合成约 0.2-0.4 g。它在老年、卧床、极端节食这三类人身上是真有效的。
肌酸根本不在蛋白代谢这条线上: 它是能量底物, 把磷酸肌酸身上的磷酸转给 adenosine triphosphate: The cell's universal energy currency — almost everything that costs energy spends it., 让 ATP 重新灌满。红肉和鱼一天给你约 1-2 g, 纯素饮食接近 0。额外补 5 g/天 是 A 级证据, 几乎适合所有训练人群。
于是三条不重叠就清楚了: 肌酸管能量、HMB 管平衡, 一个不影响另一个; 亮氨酸管开关、HMB 管刹车, 互补, 但优先级是亮氨酸在前。三者一起堆当然可以, 只是收益递减——蛋白质已经 1.6-2.2 g/kg、肌酸 5 g/天、训练也够, HMB 的边际几乎为零。
Wilson 2013 的 ISSN 立场文件给训练补剂排了一个优先级, 值得抄下来:
1. 训练计划 + 充足蛋白 (基础, A 级)
2. 肌酸 5 g/天 (A 级, 适合几乎所有训练人群)
3. 咖啡因 (A 级, 急性效应)
4. β-丙氨酸 (B 级, 高强度糖酵解窗口)
5. HMB 3 g/天 (B 级, 节食、老年、卧床场景)
6. citrulline (B 级, pump + 血流)
7. TMG (betaine) 2.5 g/天 (B-C 级, 力量训练边际)
8. 其它 (D-C 级)
落到人身上: 健康青年想简单增肌, 蛋白 + 训练 + 肌酸就够了, HMB 不优先; 老年、术后、卧床的人, HMB 反而是这张表里靠前的工具, 远超其它健身房补剂; 运动员在极端减脂期要保肌肉, 可以 HMB + 肌酸 + 高蛋白 + 训练同时上。如果你是健康青年又很想试 HMB——同样的钱花在睡眠、训练和蛋白质上, 性价比更高。
Why HMB may not work for you
'Why doesn't HMB work for me?' is a common gym-forum question, and the answer is usually 'you're not in the population where it works'.Conditions that drive HMB's margin to zero (high probability):
1. Daily protein 1.6 g/kg+ + stable training plan + sleep 7–8 h — once these three are in place, HMB's anti-catabolic contribution is suppressed by the foundation
2. Healthy young (18–40) + no chronic disease + 1+ years of training — limited UPS upregulation, so HMB has little to suppress
3. Goal is hypertrophy / strength — not HMB's strong suit
4. Training volume isn't huge — not much muscle damage to protect against
Conditions that make HMB useful (any 1+):
1. Elderly (60+) — anabolic resistance + UPS upregulation
2. Currently or about to be bedridden / hospitalized / post-op — acute catabolism risk
3. Very-low-calorie cutting + wanting to preserve muscle — dieting-state muscle breakdown
4. Chronic illness (cancer, COPD, HIV) — cachexia risk
5. Training beginner + simultaneously high-intensity training + protein not meeting target — anti-catabolic + anti-damage
6. On steroid therapy (long-term prednisone etc.) — drug-induced breakdown
Cost-effectiveness:
HMB 3 g/day: ~$25-40/monthvs creatine 5 g/day: ~$5-10/monthvs protein powder + food: depends on intake, typically $30-60/month
Summary for typical gym readers:
You probably don't need HMB. Spend the money on:
Better food (chicken breast, fish, eggs, beans)Creatine (A-grade evidence, works for almost all training populations)A cup of coffee (acute performance)Sleep improvement (mattress, blackout curtains)
ROI is higher than HMB for any of these.
For your 60+ parents / family member about to have surgery / long-term bedridden patient:
HMB is a genuinely important tool. Discuss with nutrition / geriatrics.
Chapter 5
Decision tree
Decision tree
Do you need to supplement HMB?
Strongly recommended populations:
1. 60+ elderly + muscle mass / gait speed decline: 3 g/day + protein 1.2–1.5 g/kg + resistance training
2. Pre-op / post-op / expected bedrest >1 week: 3 g/day + early ambulation
3. ICU high-catabolic state: clinician decides (Juven-class formula)
4. Cancer / chronic illness with cachexia risk: discuss with oncology / internal medicine nutrition support team
5. Long-term steroid therapy (prednisone >7.5 mg/day for >3 months): anti-catabolic supplement, discuss with physician
Worth considering:
6. Athletes in extreme cutting (pre-contest / natural bodybuilding): 3 g/day + high protein + resistance training
7. Beginners + protein not meeting target but working on it: short-term 3 g/day as a bridge
Low priority / not recommended:
Healthy young + simple hypertrophy: skip, spend money on creatine + proteinEndurance athletes (running / cycling / swimming / rowing): anti-catabolism isn't the bottleneck, skip'Anti-aging' / 'long-term use to stay young': no evidence, skipAs a fat-loss drug: HMB isn't a fat-loss drug, don't misuse
Dose:
Standard protocol: 3 g/day divided (1.5 g × 2 or 1 g × 3)Training day: 1 hour pre-training + post-training + before bedNon-training day: divided across the three mealsDuration: at least 2–8 weeks to observe effect (unlike creatine, HMB is not an acute-effect supplement)
Forms:
HMB-Ca (calcium salt, calcium HMB): cheapest, $25-40/monthHMB-FA (free acid): more expensive ($40-70/month), slightly more stable absorption, small clinical differenceJuven combo: HMB + glutamine + arginine, clinically used, not a general consumer supplementAvoid: 'HMB + protein powder' blends (HMB dose usually inadequate) / 'HMB + creatine + leucine triple' marketing confusion
Safety:
Very safe: long-term use (1+ year) studies show no significant side effectsOne note: HMB-Ca contains calcium — 3 g HMB-Ca per day ≈ 270 mg calcium; count toward daily calcium intake
Atlas overall verdict: HMB is the most underestimated 'clinically-positioned supplement' in the aisle — not because no one markets it, but because its target population isn't the gym reader. If you read this far and concluded 'I'm not in its target group', that's exactly what the atlas teaching aimed for: honestly evaluating whether a supplement is right for you is far better than blindly following marketing.
Strongly recommended populations:
1. 60+ elderly + muscle mass / gait speed decline: 3 g/day + protein 1.2–1.5 g/kg + resistance training
2. Pre-op / post-op / expected bedrest >1 week: 3 g/day + early ambulation
3. ICU high-catabolic state: clinician decides (Juven-class formula)
4. Cancer / chronic illness with cachexia risk: discuss with oncology / internal medicine nutrition support team
5. Long-term steroid therapy (prednisone >7.5 mg/day for >3 months): anti-catabolic supplement, discuss with physician
Worth considering:
6. Athletes in extreme cutting (pre-contest / natural bodybuilding): 3 g/day + high protein + resistance training
7. Beginners + protein not meeting target but working on it: short-term 3 g/day as a bridge
Low priority / not recommended:
Healthy young + simple hypertrophy: skip, spend money on creatine + proteinEndurance athletes (running / cycling / swimming / rowing): anti-catabolism isn't the bottleneck, skip'Anti-aging' / 'long-term use to stay young': no evidence, skipAs a fat-loss drug: HMB isn't a fat-loss drug, don't misuse
Dose:
Standard protocol: 3 g/day divided (1.5 g × 2 or 1 g × 3)Training day: 1 hour pre-training + post-training + before bedNon-training day: divided across the three mealsDuration: at least 2–8 weeks to observe effect (unlike creatine, HMB is not an acute-effect supplement)
Forms:
HMB-Ca (calcium salt, calcium HMB): cheapest, $25-40/monthHMB-FA (free acid): more expensive ($40-70/month), slightly more stable absorption, small clinical differenceJuven combo: HMB + glutamine + arginine, clinically used, not a general consumer supplementAvoid: 'HMB + protein powder' blends (HMB dose usually inadequate) / 'HMB + creatine + leucine triple' marketing confusion
Safety:
Very safe: long-term use (1+ year) studies show no significant side effectsOne note: HMB-Ca contains calcium — 3 g HMB-Ca per day ≈ 270 mg calcium; count toward daily calcium intake
Atlas overall verdict: HMB is the most underestimated 'clinically-positioned supplement' in the aisle — not because no one markets it, but because its target population isn't the gym reader. If you read this far and concluded 'I'm not in its target group', that's exactly what the atlas teaching aimed for: honestly evaluating whether a supplement is right for you is far better than blindly following marketing.
实操 · 谁该补、怎么吃、买哪一种
强推荐的人群1. 60+ 老年人 + 肌肉量、行走速度下降: 3 g/天 + 蛋白 1.2-1.5 g/kg + 力量训练
2. 术前、术后、卧床预期 > 1 周: 3 g/天 + 早期下床
3. 重症 ICU 高分解状态: 临床医师决定 (Juven 类配方)
4. 癌症、慢性病恶病质风险: 与肿瘤科、内科营养支持团队讨论
5. 类固醇长期治疗 (强的松 > 7.5 mg/天 > 3 个月): 抗分解补充, 与医生讨论
可以考虑的人群
6. 运动员极端减脂期 (赛前、自然健美): 3 g/天 + 高蛋白 + 力量训练
7. 训练新手 + 蛋白未达标但正在努力补: 短期 3 g/天 作为过渡
怎么吃
标准协议是 3 g/天分次服用 (1.5 g × 2 或 1 g × 3)。训练日可以放在训练前 1 小时、训练后和睡前; 非训练日就跟着三餐分开吃。要给它至少 2-8 周才谈得上看效果——这一点和肌酸很不一样, HMB 没有急性效应, 吃一次不会有任何感觉。
买哪一种
最常见也最便宜的是 HMB-Ca (钙盐), 约 $25-40/月; HMB-FA (自由酸) 贵一些 ($40-70/月), 吸收稍稳定, 但临床差异很小。Juven 那种 HMB + 谷氨酰胺 + 精氨酸的复方是临床用品, 不是普通保健补剂。要避开的是HMB + 蛋白粉的混合装 (里面的 HMB 剂量通常不够), 以及HMB + 肌酸 + 亮氨酸三联这类把三种不同机制混为一谈的营销。
安全性
HMB 的安全记录很干净: 连续用 1 年以上的多项研究都没发现显著副作用。唯一要记一笔的是钙——HMB-Ca 本身含钙, 一日 3 g HMB-Ca 约等于 270 mg 钙, 记得把它算进你每天的钙摄入里。
Position in the G4 supplement landscape
HMB's position in the atlas Supplements continent:| Dimension | HMB | Creatine | β-alanine | Citrulline | TMG / glycine |
|---|---|---|---|---|---|
| Mechanism clarity | A | A | A | A | A |
| Clinical evidence | A (elderly) B (young) | A (training) | B (1-4 min) | B (pump) | B (Hcy/training) |
| Target audience breadth | Narrow (elderly / bedrest) | Broad (training) | Narrow (high-intensity intervals) | Narrow (pump training) | Mid (general + MTHFR) |
| Cost-effectiveness | Mid ($25-40) | Very high ($5-10) | Mid ($10-20) | High ($10-20) | Very high ($5-15) |
| Marketing intensity | Low | Mid | Mid | Mid | Very low |
| Side effects | Very low | Very low | Tingling | Low (nitrate contraindication) | Low (high LDL warning) |
So:
If you're a general trainee: creatine + protein + training is the base; everything else is marginalIf you're a family caregiver: HMB suddenly becomes far more relevant than other 'gym supplements'If you're a self-quantification enthusiast: TMG + glycine + NAC are the atlas-recommended 'cold, cheap, genuinely effective' starting points; HMB sits at Wilson 2013 ISSN priority #5
This is another concrete instance of the atlas's overall product philosophy: no supplement matters to everyone, and no supplement is useless to everyone — evaluating supplements isn't evaluating molecules, it's evaluating the molecule × person × state triple. Once you internalize that framework, no new 'revolutionary supplement' marketing has leverage on you anymore.
References · 5
- Wilson, J. M., Fitschen, P. J., Campbell, B., et al. (2013). International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB). Journal of the International Society of Sports Nutrition, 10, 6. 10.1186/1550-2783-10-6
- Holecek, M. (2017). Beta-hydroxy-beta-methylbutyrate supplementation and skeletal muscle in healthy and muscle-wasting conditions. Journal of Cachexia, Sarcopenia and Muscle, 8(4), 529-541. 10.1002/jcsm.12208
- Deutz, N. E. P., Pereira, S. L., Hays, N. P., et al. (2013). Effect of β-hydroxy-β-methylbutyrate (HMB) on lean body mass during 10 days of bed rest in older adults. Clinical Nutrition, 32(5), 704-712. 10.1016/j.clnu.2013.02.011
- Bear, D. E., Langan, A., Dimidi, E., et al. (2019). β-Hydroxy-β-methylbutyrate and its impact on skeletal muscle mass and physical function in clinical practice: a systematic review and meta-analysis. The American Journal of Clinical Nutrition, 109(4), 1119-1132. 10.1093/ajcn/nqy373
- Rossi, A. P., D'Introno, A., Rubele, S., et al. (2017). The potential of β-hydroxy-β-methylbutyrate as a new strategy for the management of sarcopenia and sarcopenic obesity. Drugs & Aging, 34(11), 833-840. 10.1007/s40266-017-0496-0