Place · Level 3
Protein + lifting
增肌每天该吃多少蛋白: 每公斤 1.6-2.2 克, 拆成几餐吃, 30 分钟黄金窗口是营销
Last updated
Story path
Chapter 1
Where 1.6-2.2 comes from
Where 1.6-2.2 comes from
*Morton 2018 BJSM* meta-analysis is the authoritative source for this number:
49 RCTs, n = 1863 subjectsComparing different protein intakes plus resistance training (RT) for effects on lean mass and strengthResult: the breakpoint between protein intake and lean mass gain is 1.62 g/kg/dayBeyond that point, further increases in protein give diminishing returnsThe 95% CI upper bound is about 2.2 g/kg/day, hence the recommended range of 1.6-2.2 g/kg/day
Contrast with the RDA: both the US and Chinese RDAs are 0.8 g/kg/day — that is the deficiency-prevention dose, not the training-optimization dose. For trainees, the RDA dramatically underestimates the requirement.
Example (a 70 kg trainee): 70 × 1.8 = 126 g protein/day, split across 4 meals × 30-35 g per meal.
Real-food equivalents:
100 g cooked chicken breast ≈ 28 g protein1 egg ≈ 6-7 g1 cup milk (240 mL) ≈ 8 g150 g Greek yogurt ≈ 15 g100 g tofu ≈ 8 g (firm) / 5 g (silken)
49 RCTs, n = 1863 subjectsComparing different protein intakes plus resistance training (RT) for effects on lean mass and strengthResult: the breakpoint between protein intake and lean mass gain is 1.62 g/kg/dayBeyond that point, further increases in protein give diminishing returnsThe 95% CI upper bound is about 2.2 g/kg/day, hence the recommended range of 1.6-2.2 g/kg/day
Contrast with the RDA: both the US and Chinese RDAs are 0.8 g/kg/day — that is the deficiency-prevention dose, not the training-optimization dose. For trainees, the RDA dramatically underestimates the requirement.
Example (a 70 kg trainee): 70 × 1.8 = 126 g protein/day, split across 4 meals × 30-35 g per meal.
Real-food equivalents:
100 g cooked chicken breast ≈ 28 g protein1 egg ≈ 6-7 g1 cup milk (240 mL) ≈ 8 g150 g Greek yogurt ≈ 15 g100 g tofu ≈ 8 g (firm) / 5 g (silken)
误区 · 包装上那个数是防病底线, 不是增肌量
要注意的是, 这和你在食品包装上看到的 0.8 g/kg 不是一回事。0.8 只是防止你缺蛋白、不出毛病的底线, 不是让肌肉长得最好的量; 对一个认真练的人, 这个官方推荐量低得离谱。两个数为什么差这么多
差别不在多少算够, 而在够什么用。
官方那个推荐量是从氮平衡实验里推出来的。蛋白质分子里含氮, 身体拆蛋白时会把氮变成尿素排掉。研究者给一群人喂不同量的蛋白, 量他们吃进去多少氮、又排出去多少氮, 找那个进来的刚好抵得上出去的的点。达到这个点, 意味着你身上的蛋白总量不再净流失 —— 不掉肌肉、不出缺乏症。
但不掉和长是两个目标。练力量的人要的是每天有一段时间造得比拆得多, 而且这个盈余要天天攒。原料只够打平的人, 训练在肌纤维上撕出的那些微损伤能修回来就不错了, 谈不上在原基础上加粗。
推论: 这也顺带解释了另外两件事
为什么再往上加会封顶。 原料从不够变到够, 差别很大; 从够变到更多, 多出来的那部分没有活可干, 会被拆掉当燃料烧掉。为什么后面那一幕说老年人要吃得更多。 官方那条线是照着普通成年人不出毛病画的, 而老年肌肉对同样一份蛋白的反应本来就变钝了 —— 按底线吃, 连打平都吃力。
所以以后看到一个蛋白推荐量, 先问它是照着不出毛病定的, 还是照着长肌肉定的。这两条线从来不在一个高度上。
Chapter 2
0.3-0.5 g/kg per meal
0.3-0.5 g/kg per meal
*Areta 2013* and *Schoenfeld 2018* meta-analyses reveal how much distribution actually matters:
With the same 24-hour protein total (1.6 g/kg), splitting it across 3-4 meals (0.3-0.5 g/kg per meal) is significantly better than 1-2 large mealsReason: each meal's muscle protein synthesis (MPS) has both a leucine threshold (~2.5 g) and an absorption ceiling — a single protein dose above ~40 g gives marginal benefit0.3-0.5 g/kg per meal works out to about 25-40 g of protein — enough to hit the leucine threshold without waste
Layne Norton's classic demonstration (a 70 kg trainee at 130 g protein/day):
Option A: 65 g at breakfast + 65 g at dinner (2 meals) — protein synthesis sub-optimalOption B: 32 g breakfast + 32 g lunch + 32 g dinner + 32 g pre-bed (4 meals) — protein synthesis maximized
Trent Stellingwerff's approach: 5-6 meals on training days (with a small post-training feed), 4 meals on rest days — both landing at 1.8 g/kg.
With the same 24-hour protein total (1.6 g/kg), splitting it across 3-4 meals (0.3-0.5 g/kg per meal) is significantly better than 1-2 large mealsReason: each meal's muscle protein synthesis (MPS) has both a leucine threshold (~2.5 g) and an absorption ceiling — a single protein dose above ~40 g gives marginal benefit0.3-0.5 g/kg per meal works out to about 25-40 g of protein — enough to hit the leucine threshold without waste
Layne Norton's classic demonstration (a 70 kg trainee at 130 g protein/day):
Option A: 65 g at breakfast + 65 g at dinner (2 meals) — protein synthesis sub-optimalOption B: 32 g breakfast + 32 g lunch + 32 g dinner + 32 g pre-bed (4 meals) — protein synthesis maximized
Trent Stellingwerff's approach: 5-6 meals on training days (with a small post-training feed), 4 meals on rest days — both landing at 1.8 g/kg.
机制 · 开关是什么、谁按的、为什么按不动
上面那句把开关顶过门槛是个比喻。比喻好记, 但它挡住了三个你其实推得出来的问题: 开关是什么? 谁去按它? 为什么按到一半就按不动了?一、肌肉细胞里有一个专门数亮氨酸的传感器
你吃下一块鸡胸, 蛋白在胃和小肠被拆成一个个氨基酸, 进血, 再被肌肉细胞捞进去。肌肉细胞的细胞质里有一小组蛋白, 平时的工作就是盯着亮氨酸 (leucine) 的浓度: 亮氨酸一多起来, 它们就抓住亮氨酸, 自己的形状随之改变。
为什么偏偏挑亮氨酸当信号? 因为它是必需氨基酸 —— 身体自己造不出来, 只能从食物来。所以血里亮氨酸变多, 几乎只可能是刚吃了含蛋白的东西。用它报信, 等于用一个不会误报的证据。
二、传感器一松手, mTOR complex 1: The main working form of mTOR — the switch that directly drives protein synthesis. 就被放行
那一小组传感蛋白平时并不闲着: 它们抓着另一个东西不放 —— 一个专门给 mTORC1 踩刹车的调控复合体。亮氨酸多起来, 传感器改去抓亮氨酸, 刹车就被松开了。
mTORC1 是细胞里要不要开工造东西的总闸。刹车一松, 它被拉到细胞内的溶酶体表面激活, 然后给下游几个负责启动翻译的蛋白挂上磷酸基。通俗说就是: 把核糖体从待机切到开工, 把血里的氨基酸一个接一个接到肌纤维的蛋白链上。这一刻才是肌肉蛋白合成 (MPS) 真正开始。
所以开关不只是一个说法, 它是一条很具体的链: 亮氨酸浓度上升 → 传感器松开刹车 → mTORC1 激活 → 核糖体开工。门槛之所以存在, 是因为刹车要被松开, 需要足够多的亮氨酸同时到位; 慢慢渗进来的一点点, 松不动它。
顺带解决一个很贵的误解: 亮氨酸是发令枪, 不是子弹。 它负责喊开工, 真正被砌进肌肉的是全部必需氨基酸。所以只补亮氨酸或支链氨基酸 (BCAA)、却没吃够一整份蛋白, 等于按响了开工铃却不送砖 —— 铃响了, 工地照样停着。
三、为什么单顿超过一定量就用不上
正文里那个上限不是吸收不了一句话能打发的, 它至少有两个来源。
来源一: 蛋白到你的肌肉之前, 先被抽了两道税。 蛋白拆成的氨基酸从小肠吸收, 第一站不是血, 是小肠自己的细胞 —— 肠壁细胞更新极快, 会先扣下一部分自用。剩下的经门静脉先进肝脏, 肝脏又截下一批去造血浆蛋白、做别的用途或直接当燃料。真正流到腿上、背上那块肌肉的, 只是你嘴里那一份的一部分。这就是吃了多少和肌肉拿到多少从来不是同一个数的原因。
来源二: 开工之后, 流水线本身有速度上限。 闸门开到最大, 核糖体把氨基酸接成蛋白链的速度也就那么快。再往血里灌氨基酸, 多出来的不会排队等着, 而是被拆掉当燃料烧掉或转成尿素排走。更麻烦的是, 血里氨基酸持续维持在高位时, 合成反应本身会回落 —— 肌肉像吃饱了一样对信号变钝, 而不是一直造下去。
四、这条链子能让你自己推出后面两幕
为什么植物蛋白要吃多一点: 它不是不能用, 而是同样重量里亮氨酸和其它必需氨基酸的配比稀一些 —— 发令枪的火药少, 就得多装一点才响得动。为什么老年人每餐要吃更多: 老了以后这条链上好几个环节都变钝, 同样的亮氨酸浓度松不开同样多的刹车。对策因此不是笼统地一天吃更多, 而是把单顿抬得更高, 好把那个抬高了的门槛顶过去。
一句话收: 一天的总量决定你有没有原料, 每顿的量决定这些原料有没有被叫去干活。
The 30-min protein window
See hypertrophy-mechanism for the full debunk. Bringing the data together here:*Aragon & Schoenfeld 2013* *JISSN* meta-analysis nails it down:
The real anabolic window is 24-48 hours after training, not 30 minutes24-hour total protein matters far more than timingA normal protein-containing meal 1-3 hours before training, plus another 1-2 hours after, already covers the whole window
Things not to do in practice:
Interrupting your day to make sure you get a protein shake right before training (a normal dinner already contains 30-40 g of protein)Panicking if you don't get protein within 30 min post-training (within 2-3 hours is fine)Pushing past 40 g per meal in search of "more" (absorption and leucine triggering are already saturated)
aragon-2013-jissn-window
Chapter 3
Protein quality + sources
Protein quality + sources
DIAAS (Digestible Indispensable Amino Acid Score) is the modern standard for protein quality, replacing the older PDCAAS:
The implication: animal protein has more favorable leucine and EAA ratios, making it easier to hit the MPS threshold. But plant protein is not unusable — it just needs slightly higher total intake (about 1.8-2.0 g/kg) plus protein combining (legumes + grains) to compensate for the limiting amino acid in any single plant source (soy is low in methionine, grains are low in lysine).
Practical for vegan trainees: soy protein, pea-rice protein blends, various legumes, whole grains, with occasional leucine-rich BCAA supplementation — fully workable. *Hevia-Larraín 2021* RCT showed equivalence to whey.
| Source | DIAAS | Notes |
|---|---|---|
| Whey protein | 1.09 | Benchmark |
| Milk | 1.18 | Highest |
| Egg | 1.13 | |
| Beef | 1.10 | |
| Chicken breast | 1.08 | |
| Soy protein | 0.91 | Highest plant |
| Tofu | 0.87 | |
| Pea protein | 0.65 | |
| Wheat gluten | 0.40 |
The implication: animal protein has more favorable leucine and EAA ratios, making it easier to hit the MPS threshold. But plant protein is not unusable — it just needs slightly higher total intake (about 1.8-2.0 g/kg) plus protein combining (legumes + grains) to compensate for the limiting amino acid in any single plant source (soy is low in methionine, grains are low in lysine).
Practical for vegan trainees: soy protein, pea-rice protein blends, various legumes, whole grains, with occasional leucine-rich BCAA supplementation — fully workable. *Hevia-Larraín 2021* RCT showed equivalence to whey.
数字 · DIAAS 分数表怎么读
常见蛋白的分数动物蛋白普遍排在前头, 大多在 1.1 上下, 牛奶最高, 约 1.18。植物蛋白低一截: 大豆是里面最好的, 约 0.91, 豆腐 0.87, 豌豆蛋白 0.65, 小麦面筋垫底, 只有 0.40。
这个分数是怎么量出来的
它不是在试管里泡出来的。做法是把一种蛋白喂下去, 到小肠的末端 (回肠) 把没被吸收的部分收集起来, 算出每一种必需氨基酸真正进了血的比例。老一代的 PDCAAS 是在粪便里收的, 但食物残渣走到大肠还会被细菌再改造一轮, 量出来的吸收率因此偏高 —— 这正是 DIAAS 更准的地方。
为什么用最短的那块板当分数
算出每种必需氨基酸的吸收比例之后, DIAAS 不取平均, 而是取最低的那一个当这种蛋白的分数。
理由很硬: 造一条肌肉蛋白链, 需要的氨基酸种类和比例是固定的, 缺哪一种, 链子就在那里断掉, 别的种类再富余也顶不上。这就是木桶效应 —— 一只木桶能装多少水, 由最短的那块板决定。
于是那张分数表一下就好读了:
小麦面筋垫底, 不是因为它蛋白含量低 (面筋的蛋白含量其实很高), 而是因为赖氨酸奇缺, 短板特别短。豆类缺甲硫氨酸, 谷类缺赖氨酸, 而两者缺的不是同一块板。豆子配米面, 一方的长板正好补上另一方的短板, 拼起来的那一餐, 短板就没那么短了。动物蛋白分数高, 本质上是因为它的氨基酸配比和人体自己的肌肉更接近 —— 毕竟它本来就是别的动物的肌肉。
所以实际怎么用
分数不是用来给食物排名的, 是用来提示这一餐的短板在哪。整天都吃动物蛋白的人基本不用管它; 吃素或以植物蛋白为主的人, 把它当成一张该跟谁搭的提示表: 豆配谷、豌豆配米, 一餐之内凑齐, 短板就补上了。这也是正文里说植物蛋白要吃得多一点的原因 —— 不是植物蛋白差, 而是要靠多和搭把那块短板顶上来。
Chapter 4
Older adults need more
Older adults need more
Protein requirements rise after age 60 — not because the muscle synthesis machinery becomes faster, but because it becomes blunted (anabolic resistance, *Bauer 2013*):
The older muscle's synthetic response to the same protein dose drops by about 50%The leucine threshold rises — older adults need about 35-40 g of protein per meal (vs 25-30 g in young adults) to trigger adequate MPSThe PROT-AGE Study Group 2013 recommends 1.0-1.2 g/kg/day for healthy older adults, and 1.2-1.5 g/kg/day for active older adults or those with chronic disease
The clinical implication: prevention and management of sarcopenia does not call for "gentle senior food" — it calls for a combined intervention of 30-40 g protein per meal plus 2-3 sessions of resistance training per week. In the *Fiatarone 1994* *NEJM* nonagenarian resistance training trial, protein fortification was one of the key variables.
Cross-continent references: sarcopenia / osteoporosis / vitamin-d (vitamin D improves the elderly MPS response, per *Bischoff-Ferrari 2019*).
The older muscle's synthetic response to the same protein dose drops by about 50%The leucine threshold rises — older adults need about 35-40 g of protein per meal (vs 25-30 g in young adults) to trigger adequate MPSThe PROT-AGE Study Group 2013 recommends 1.0-1.2 g/kg/day for healthy older adults, and 1.2-1.5 g/kg/day for active older adults or those with chronic disease
The clinical implication: prevention and management of sarcopenia does not call for "gentle senior food" — it calls for a combined intervention of 30-40 g protein per meal plus 2-3 sessions of resistance training per week. In the *Fiatarone 1994* *NEJM* nonagenarian resistance training trial, protein fortification was one of the key variables.
Cross-continent references: sarcopenia / osteoporosis / vitamin-d (vitamin D improves the elderly MPS response, per *Bischoff-Ferrari 2019*).
临床 · 推荐量、试验, 以及钝在哪一环
针对老年人的推荐量健康老人每公斤 1.0-1.2 g, 还在运动或有慢性病的 1.2-1.5 g (PROT-AGE 2013)。
注意这两条线都低于练力量的人那个区间, 却高于给一般成年人的官方底线 —— 它们要解决的问题不同: 前者是长, 后者是别掉。而对老年人来说这两件其实是同一件事, 因为不主动往上顶, 默认方向就是往下掉。
边练边吃, 九十多岁也长得动
Fiatarone 1994 那项著名的高龄力量训练试验里, 加强蛋白就是关键的一环。它值得记住的不是老人也能练这句励志话, 而是练和吃在这里是绑在一起的两个变量: 只给蛋白不练, 多出来的氨基酸没有信号叫它们进肌肉; 只练不吃够, 训练发出了信号却没有原料。
老年肌肉到底钝在哪一环
肌肉合成那条链子 (亮氨酸浓度上升 → 细胞里的传感器松开刹车 → mTOR complex 1: The main working form of mTOR — the switch that directly drives protein synthesis. 激活 → 核糖体开工) 在老年人身上不是断了, 而是每一环都松了一点, 累加起来就成了同一份蛋白, 反应只剩一半:
送不进去: 吃完饭后流向肌肉的血流增加得比年轻时少, 携带氨基酸和胰岛素的血到不了肌纤维旁边, 局部信号浓度自然不够。半路被扣得更多: 肠壁和肝脏那两道税随年龄变重, 同一份蛋白里能到达肌肉的那部分变少了。信号本身变钝: 就算亮氨酸浓度到位, 细胞内那套感受它的机器反应也没年轻时利落, 同样的浓度松不开同样多的刹车。
所以对策不是笼统地多吃
三条都指向同一个做法: 把单顿抬高, 而不是把总量摊薄。门槛抬高了, 就得用更大的一份把它顶过去 —— 这正是老年人每餐吃多少比一天吃多少更关键的原因。
抗阻训练在这里还有一层额外作用: 练过之后的一段时间里, 肌肉对氨基酸的敏感度会回升。也就是说, 练本身在部分抵消钝 —— 这是为什么正经的老年营养方案几乎不会只写吃、不写练。
想再往深走
顺着连到肌少症 (sarcopenia)、骨质疏松 (osteoporosis) 和维生素 D —— 维生素 D 能改善老年肌肉对蛋白的合成反应 (Bischoff-Ferrari 2019)。
References · 5
- Morton, R. W., et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine, 52(6), 376–384. 10.1136/bjsports-2017-097608
- Phillips, S. M. (2016). The impact of protein quality on the promotion of resistance exercise-induced changes in muscle mass. Nutrition & Metabolism, 13, 64. Per-meal 0.3-0.5 g/kg distribution + DIAAS-quality dominates over total intake alone. 10.1186/s12986-016-0124-8
- Areta, J. L., Burke, L. M., Ross, M. L., Camera, D. M., West, D. W. D., Broad, E. M., et al. (2013). Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. Journal of Physiology, 591(9), 2319-2331. With 80 g protein over 12 h, 4×20 g every 3 h maximized myofibrillar protein synthesis vs 8×10 g/1.5 h and 2×40 g/6 h. 10.1113/jphysiol.2012.244897
- Fiatarone, M. A., O'Neill, E. F., Ryan, N. D., Clements, K. M., Solares, G. R., Nelson, M. E., et al. (1994). Exercise training and nutritional supplementation for physical frailty in very elderly people. New England Journal of Medicine, 330(25), 1769-1775. 10.1056/NEJM199406233302501
- Bauer, J., Biolo, G., Cederholm, T., Cesari, M., Cruz-Jentoft, A. J., Morley, J. E., et al. (2013). Evidence-based recommendations for optimal dietary protein intake in older people: PROT-AGE Study Group. JAMDA, 14(8), 542-559. 10.1016/j.jamda.2013.05.021