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
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.
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'.
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
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.
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.