How Much Protein Do You Really Need per Day? Protein Powder Does Not Build Muscle “Just by Drinking It” [2026 Evidence Edition]

[Level 2 (Moderate–High)] [Food & Nutrition] [Series: Health for Serious Middle-Agers]

⚠️ Before You Read This Article

This article is educational information based on peer-reviewed literature on protein intake and protein supplements (consensus documents, RCTs, meta-analyses, and cohort studies). It is not a substitute for medical advice. If you have reduced kidney function (eGFR below 60, or proteinuria), be sure to consult your physician before increasing your protein intake or using protein powder.

Key Points of This Article (3-Line Summary)

• The official recommendation of 0.8 g/kg is the “amount that avoids deficiency.” For people in their 50s and beyond, 1.0–1.2 g/kg, and 1.2–1.6 g/kg if you do resistance training, is the international consensus (PROT-AGE, ESPEN).
• In healthy kidneys, a high-protein diet does not worsen kidney function (meta-analysis of 28 RCTs). However, CKD and a history of cardiovascular disease are a different matter.
• Protein powder is “a tool for filling the gap your diet leaves.” The added benefit for healthy people who do not also do resistance training is small; the effect is clear only in people with a tendency toward sarcopenia combined with resistance training.

1. The 0.8 g/kg Recommendation Is Only a “Minimum Line”

The Recommended Dietary Allowance in Japan’s Dietary Reference Intakes (65 g for men, 50 g for women) and the WHO figure of 0.8 g/kg are the amounts determined by nitrogen balance studies as “below this, deficiency occurs.” As the amount needed to maintain muscle and slow age-related functional decline, international expert panels have put forward higher values.

PROT-AGE (Bauer et al., J Am Med Dir Assoc 2013) and ESPEN (Deutz et al., Clin Nutr 2014) both recommend 1.0–1.2 g/kg/day for healthy people aged 65 and over, 1.2 or more for those who exercise, and 1.2–1.5 g/kg for those with acute or chronic illness or malnutrition. For a body weight of 60 kg, that is 60–72 g; for 70 kg, 70–84 g.

To be candid about the limitations, these are consensus documents, and no long-term RCT has directly proven that “raising intake to 1.2 g/kg reduces mortality or the need for long-term care.” Even so, there is consistent support on the intermediate endpoints of maintaining muscle mass and strength, and this is the current mainstream view.

2. Does High Protein Harm the Kidneys?

In healthy kidneys, the best evidence says it does not. Devries et al. (J Nutr 2018) pooled 28 RCTs with 1,358 participants and showed no difference in the change in GFR (a marker of kidney function) with protein intakes of 1.5 g/kg or more, or 20% or more of total energy (SMD 0.11). The participants included people with obesity and type 2 diabetes.

There are, however, two exceptions. The first is people who already have chronic kidney disease (CKD). The KDOQI 2020 guideline recommends 0.55–0.60 g/kg for CKD stages 3–5 (0.6–0.8 for diabetic kidney disease) (although Cochrane 2020 found “little to no difference” in slowing progression, and the UK Kidney Association recommends 0.8–1.0, so there is disagreement). The second is people with a history of cardiovascular disease. In Esmeijer et al. (Nephrol Dial Transplant 2020, post-myocardial infarction patients aged 60–80, N=2,255), the annual decline in eGFR in the group consuming more than 1.2 g/kg was roughly twice that of the group consuming less than 0.8 (observational study).

3. Animal or Plant Protein?

Large cohort studies consistently favor plant protein. In Song et al. (JAMA Intern Med 2016, N=131,342), each 10% increase in animal protein as a share of total energy was associated with an all-cause mortality HR of 1.08, while each 3% increase in plant protein was associated with an HR of 0.90. Naghshi et al. (BMJ 2020, 31 cohorts, 715,000 participants) likewise found a favorable all-cause mortality RR of 0.92 for high plant protein intake, and RR 0.94 for total protein as well.

Bear in mind, however, that the harm from animal protein was concentrated among people with unhealthy lifestyle habits such as smoking and obesity, and that the benefit of plant protein is heavily confounded with fiber and unsaturated fatty acids. Whether the effect is from “the type of protein itself” or from “the dietary pattern that contains it” has not been separated.

4. The Controversy: “High Protein at Ages 50–65 Increases Mortality”

Levine et al. (Cell Metab 2014, NHANES III, N=6,381) reported that among people aged 50–65, those who obtained 20% or more of total energy from protein had roughly 1.7 times the all-cause mortality and roughly 4 times the cancer mortality, whereas over age 65 the association reversed; this attracted considerable attention (the exact effect sizes should be confirmed in the original paper). A mechanism mediated by IGF-1 has been proposed.

However, this study has been criticized because dietary assessment relied on a single 24-hour recall and adjustment for smoking, obesity, and socioeconomic status was insufficient. In the Naghshi 2020 meta-analysis, there was no association between total protein and cancer mortality, and with a plant-based emphasis, Levine’s concern largely disappeared. At present, the conclusion that “people in their 50s should eat a low-protein diet” diverges from mainstream guidelines and cannot be adopted.

5. Does Protein Powder Work?

To state the conclusion first: “It works together with resistance training; it does not work just by drinking it.”

In Morton et al. (Br J Sports Med 2018, 49 RCTs, 1,863 participants), adding protein supplementation to 6 or more weeks of resistance training significantly increased strength, fat-free mass, and muscle fiber cross-sectional area. However, the effect shrank with age, and plateaued at a total intake of about 1.6 g/kg/day (no additional benefit from going higher).

In older adults, Liao et al. (Nutrients 2024, network meta-analysis, 78 RCTs, 5,272 participants) found that “combined with resistance training,” whey, soy, and milk protein were effective for muscle mass, grip strength, and walking speed, whereas “without exercise” there was only a small effect on grip strength. On the other hand, in healthy older adults in Labata-Lezaun et al. (2020), there was no difference from resistance training alone (grip strength SMD 0.03). In other words, the overall picture is that the effect is clear in “those with a tendency toward sarcopenia or malnutrition, combined with resistance training,” while the added benefit in healthy people is small.

As for safety, there is no problem if your kidneys are healthy (Section 2). If you are lactose intolerant, choose whey isolate or a soy- or pea-based product. Reports of heavy metal contamination in commercial powders are not peer-reviewed, so judgment is reserved.

6. The Current Situation in Japan and the Problem of “Distribution”

According to the 2023 edition of Japan’s National Health and Nutrition Survey, average intake among adults aged 20 and over is about 71 g/day, and about 73 g among those aged 65–74. For a body weight of 60 kg, that is about 1.2 g/kg, so looking at the average alone, intake is sufficient. The problem is the distribution: among thin older women and people with low energy intake, there is a segment that falls below 1.0 g/kg.

The other challenge is distribution across meals. The per-meal amount at which muscle protein synthesis plateaus is about 0.4 g/kg in older adults (about 28 g for a 70 kg person, equivalent to about 2.5–3 g of leucine: Moore et al., J Gerontol A 2015). Japanese breakfasts tend to be centered on staple carbohydrates and low in protein. In Mamerow et al. (J Nutr 2014, N=8), an even distribution (30/30/30 g) produced about 25% higher 24-hour muscle protein synthesis than a skewed distribution, but the study was small and short-term, and superiority on long-term muscle mass outcomes has not been established.

7. Conditional Conclusions

The place of protein powder is as “a tool to supplement meals that do not reach 20 g, such as breakfast.” It cannot be said that healthy people who do not also do resistance training will gain muscle just by drinking it.

8. Frequently Asked Questions

Q. As long as I meet the daily total, is it fine to take it all in one sitting? A. Because muscle protein synthesis saturates at about 0.4 g/kg per meal, splitting it across three meals is theoretically more advantageous. However, superiority on long-term outcomes has not been established, so think in the order of “total first, then distribution.”

Q. Is protein bad for the kidneys? A. In healthy kidneys, meta-analyses of RCTs have not shown any worsening. It is a different matter for people with CKD, proteinuria, or a history of cardiovascular disease, who need their physician’s judgment.

Q. Can I build muscle with plant protein too? A. Soy, pea, and other plant proteins are effective as long as you secure enough leucine (Liao 2024). Taking a somewhat larger per-serving amount than with whey narrows the gap.

References and Sources

• Bauer J, et al. (2013). PROT-AGE Study Group. J Am Med Dir Assoc 14:542-559. DOI: 10.1016/j.jamda.2013.05.021
• Deutz NEP, et al. (2014). ESPEN Expert Group. Clin Nutr 33:929-936. PMID: 24814383
• Devries MC, et al. (2018). Changes in kidney function do not differ between healthy adults consuming higher- compared with lower- or normal-protein diets. J Nutr 148:1760-1775.
• Esmeijer K, et al. (2020). Dietary protein intake and kidney function decline after myocardial infarction. Nephrol Dial Transplant 35:106-115.
• Ikizler TA, et al. (2020). KDOQI Clinical Practice Guideline for Nutrition in CKD. Am J Kidney Dis 76(3 Suppl 1):S1-107.
• Song M, et al. (2016). Association of animal and plant protein intake with all-cause and cause-specific mortality. JAMA Intern Med.
• Naghshi S, et al. (2020). Dietary intake of total, animal, and plant proteins and risk of all-cause mortality. BMJ 370:m2412. PMID: 32699048
• Levine ME, et al. (2014). Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population. Cell Metab 19:407-417.
• Morton RW, et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains. Br J Sports Med 52:376-384. PMID: 28698222
• Liao CD, et al. (2024). Network meta-analysis of protein supplementation and resistance training in older adults. Nutrients.
• Moore DR, et al. (2015). Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. J Gerontol A 70:57-62. PMID: 25056502
• Ministry of Health, Labour and Welfare (2025). Summary of Results of the 2023 National Health and Nutrition Survey, Japan

Evidence current as of October 2026. Final verification of effect sizes such as those in Levine 2014 against the original paper is recommended.