- The RDA for protein (0.8 g/kg/day) was set to prevent deficiency — not to optimize muscle, especially with age or during weight loss.
- Expert groups recommend older adults get roughly 1.0–1.2 g/kg/day or more, and active or dieting adults often benefit from 1.6–2.2 g/kg/day.
- Distribution matters: spreading protein across meals (with enough per meal) supports muscle better than one big serving.
- Protein plus resistance training is the combination that actually builds and preserves muscle — neither works as well alone.
Ask most people how much protein they need, and they will cite a number that was never meant to answer that question. The official RDA for protein — 0.8 grams per kilogram of body weight per day — was set to prevent deficiency in the average sedentary adult. Preventing deficiency and protecting muscle are different goals, and if your aim is the second, the RDA is too low.
What "enough" really means
The RDA is a floor, not a target. It answers "how little can I get away with?" — not "how much helps me keep muscle, control blood sugar, and age strong?" For those goals, the evidence points substantially higher:
- Older adults. The PROT-AGE expert group recommends roughly 1.0 to 1.2 grams per kilogram per day for healthy older adults, and more (up to ~1.5) for those who are ill or highly active — precisely because muscle becomes harder to maintain with age.
- Active or dieting adults. People who train, or who are losing weight, generally do best around 1.6 to 2.2 grams per kilogram per day, to protect muscle against the double stress of exercise and a calorie deficit.
For a 70-kilogram (155-pound) person, that is a jump from about 56 grams a day at the RDA to well over 100 — a meaningful difference you have to plan for.
Why more, as you age
Two things happen with age that raise protein needs. First, anabolic resistance: older muscle responds less efficiently to a given dose of protein, so it takes a bit more to trigger the same muscle-building signal. Second, life tends to reduce both appetite and activity, quietly cutting intake at exactly the time the body needs more. Left unaddressed, the result is sarcopenia — the slow loss of muscle that drives frailty, falls, and lost independence.
Timing and distribution
Total daily protein matters most, but distribution helps. Muscle responds to protein in a pulse-like way, so spreading intake across meals — with enough at each (roughly 30–45 grams) — supports muscle better than loading it all at dinner. A protein-forward breakfast is where most people have the biggest gap.
Protein without training is half the recipe
Here is the crucial caveat: protein is the building material, but resistance training is the signal to use it. A meta-analysis found that protein supplementation meaningfully enhanced the muscle and strength gains from resistance training — but the training was doing the heavy lifting, with protein amplifying the result. Eating more protein while sitting still will not build much. Pair adequate protein with two or more resistance sessions a week, and you have the combination that actually preserves and builds muscle.
The practical version
You do not need to weigh every meal. Anchor each meal with a clear protein source, prioritize it at breakfast, lean toward the higher end while losing weight or as you age, and use a shake to fill gaps on busy or low-appetite days. Then lift. Protein is not about chasing a bodybuilder's physique — it is about keeping the muscle that keeps you independent, metabolically healthy, and strong for decades.
In practice: why this matters
As populations age, sarcopenia — the loss of muscle with age — drives an enormous burden of frailty, falls, and lost independence. A nutrition guideline that merely prevents deficiency leaves most older adults under-fueled for muscle maintenance. Updating everyday expectations about protein, especially for older and dieting adults, is a simple, low-cost lever with outsized effects on how a society ages.
Frequently asked questions
Isn't too much protein bad for the kidneys?
For people with healthy kidneys, higher protein intakes in these ranges have not been shown to cause kidney damage. People with existing kidney disease do need individualized limits — so check with your clinician if that applies to you. For most healthy adults, under-eating protein is the more common problem.
Does the type of protein matter?
Quality and leucine content matter for the muscle-building signal — animal proteins and some plant combinations are efficient sources. Plant-based eaters can absolutely meet needs with attention to variety and slightly higher totals. Whole-food sources also bring other nutrients, so aim for food first and use powders to fill gaps.
References
- Bauer J, Biolo G, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. Journal of the American Medical Directors Association. 2013;14(8):542–559. doi:10.1016/j.jamda.2013.05.021
- Morton RW, Murphy KT, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training–induced gains in muscle mass and strength. British Journal of Sports Medicine. 2018;52:376–384. doi:10.1136/bjsports-2017-097608
Peer-reviewed sources located via PubMed and cited for education. Citations reflect published research at time of writing.
Dr. Andrew Simon, ND, BCB
Licensed naturopathic physician and board-certified biofeedback practitioner in Seattle. Clinic Director of Rebel Med NW, adjunct clinical faculty at Bastyr University, six-time Seattle Met Top Doctor, and the naturopathic advisor to Washington State on Long COVID. Read full bio →
This article is for educational purposes and is not a substitute for individualized medical care. Talk with a qualified clinician about your specific situation.