How much protein do I need per day?

The RDA of 0.8 g/kg is a minimum to prevent deficiency, not optimal. Active adults need 1.2–1.6 g/kg. People building muscle should target 1.6–2.2 g/kg (0.7–1.0 g/lb). Cutting calories? Aim higher — 2.2–2.6 g/kg — to preserve lean mass while losing fat. Older adults benefit from 1.2–1.5 g/kg minimum to fight sarcopenia.

Is too much protein bad for kidneys?

For people with healthy kidneys, no. A 2018 systematic review found high-protein diets up to 2.8 g/kg do not harm kidney function in healthy adults. Anyone with chronic kidney disease should follow their nephrologist's protein limit (typically 0.6–0.8 g/kg).

How should I split protein across meals?

Distribute roughly evenly across 3–5 meals, each containing 0.4 g/kg (about 25–40 g for most adults). Muscle protein synthesis is maximised by ~3 hourly doses around the leucine threshold (~2.5 g leucine). Eating all your protein in one meal works but is suboptimal for muscle building.

What are the best protein sources?

Highest quality (complete amino acid profile, high digestibility): chicken breast, eggs, Greek yogurt, lean beef, fish, whey protein, cottage cheese. Plant sources: soy, tofu, tempeh, lentils, chickpeas, quinoa. Vegans should slightly increase total protein (1.2× factor) to compensate for lower digestibility scores.

Do I need a protein shake?

No — but they're convenient. If you can hit your daily target through whole food, you don't need supplements. Whey or pea protein helps when you're travelling, post-workout, or struggling to reach 30 g per meal. Aim to get most protein from food first.

🍗 蛋白质摄入量计算器

根据体重和目标，以克为单位计算每日蛋白质需求。包含肌肉蛋白质合成的每餐建议摄入量。

单位

体重（公斤）

目标

每日餐数

⚠️ 一般性指导。 患有慢性肾病、透析患者或有特定疾病的人群应遵循医生规定的蛋白质摄入上限。妊娠、哺乳期和精英运动训练有特殊需求——请咨询注册营养师。

为何蛋白质很重要

蛋白质是您的身体唯一无法以有意义方式储存的宏量营养素。每个细胞 — 肌肉、皮肤、头发、酶、激素、免疫抗体 — 都需要持续的氨基酸供应。达到充足的每日蛋白质摄入量是身体成分、训练后恢复、节食时的饱腹感以及(老年人)肌肉保护方面影响力最大的单一营养变量。

您实际需要多少？

0.8克/公斤的每日推荐摄入量是minimum to prevent deficiency，而非最优值。现代运动营养学共识（ISSN，2017年）：

Sedentary adults: 0.8–1.0 g/kg
Active adults / general fitness: 1.2–1.6克/千克
Building muscle: 1.6-2.2 g/kg（0.7-1.0 g/磅）
Cutting (fat loss): 2.2-2.6 g/kg — 在热量赤字期间保留瘦体重需要较高摄入
Endurance athletes: 1.4–2.0 g/kg
Adults 50+: 至少 1.2–1.5 g/kg 以对抗与年龄相关的肌肉流失

按餐分配

肌肉蛋白质合成似乎在蛋白质分散于3–5 meals、每次摄入约0.4 g/kg时达到最大化。对于80千克的人，每餐约需32克——相当于一个鸡胸肉、一大罐金枪鱼或200克希腊酸奶。将所有蛋白质集中在一顿晚餐中摄入，技术上可达到每日总量，但肌肉增长效果较差。

质量也很重要

蛋白质质量通过 DIAAS（可消化必需氨基酸评分）来衡量。乳清蛋白、牛奶、鸡蛋和牛肉的评分均超过100。大多数植物蛋白评分较低（扁豆约60，花生约43），因为它们缺乏一种或多种必需氨基酸。Vegans 应适当提高总摄入量（约1.2倍系数），并搭配多种食物来源（米饭+豆类，燕麦+大豆）以获得完整的氨基酸谱。

常见误区

"High protein damages kidneys" — 只有在您已患有慢性肾脏病的情况下才成立。健康的肾脏可以处理每千克体重高达2.8克而不会出现问题。
"You can only absorb 30 g per meal" — 错误。您摄入的所有蛋白质都会被吸收；问题只是它用于肌肉合成的效率（在每餐约0.4克/千克时达到平台期）。
"You need a shake immediately after training" — 训练后的「合成代谢窗口」更接近4–6小时，而非30分钟。每日总量远比时机重要。

与TDEE和宏量营养素配合使用

蛋白质是宏量营养素三要素之一。将此计算器与我们的TDEE Calculator（总卡路里）和Macro Calculator（碳水/脂肪分配）结合使用。

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重要提示： 这些是健康成年人的一般指南。任何患有慢性肾病、肝病或正在进行透析的人都应遵循其肾病专家的特定蛋白质限量。怀孕、哺乳和青少年运动员有额外需求 — 请咨询注册营养师。