How Much Protein Do You Need as You Age?

The protein debate starts with a simple distinction: the Recommended Dietary Allowance (RDA) of 0.8 grams per kilogram of body weight per day (g/kg/day) was designed as a minimum to avoid deficiency, not as a proven longevity target. The 2025-2030 Dietary Guidelines for Americans explicitly recommended 1.2 to 1.6 g/kg/day, but the strongest peer-reviewed support for that range comes from muscle, body composition, and older-adult nutrition research. It does not come from long-term randomized trials showing fewer diseases or longer life.

Where the evidence is strongest

Older-adult nutrition expert groups have recommended at least 1.0 to 1.2 grams per kilogram of body weight per day (g/kg/day) for healthy older adults and 1.2 to 1.5 g/kg/day during short-term or chronic illness. Sarcopenia, meaning age-related loss of muscle mass and function, is the main concern these recommendations are trying to address.

The human trial evidence is mixed, but it points in a practical direction. A 2022 systematic review and meta-analysis, which pooled 74 randomized controlled trials, found that increasing daily protein produced small gains in lean body mass, meaning body mass other than fat, during strength training. In adults aged 65 and older, benefits were seen at 1.2 to 1.59 g/kg/day. Another 2022 meta-analysis of randomized trials in older adults found that protein combined with strength training improved appendicular lean mass, meaning lean mass in the arms and legs, by 0.54 kilograms and handgrip strength by 1.71 kilograms compared with lower-protein control groups. The appendicular lean mass benefit was significant in sarcopenic or frail adults, not in healthy older adults.

Protein alone is less impressive. A 12-week randomized placebo-controlled trial of 116 physically active older adults with low usual protein intake found improved lean body mass with supplementation, but no significant improvement in strength or physical performance. The trial may have had limited room to show performance gains because participants were already high functioning. Other pooled analyses report a similar pattern: lean mass may move modestly, while strength usually requires training.

Why the target is not 2.2 g/kg/day for everyone

Some commentaries argue for protein intakes approaching 1 gram per pound of body weight, roughly 2.2 grams per kilogram of body weight per day (g/kg/day). That is a different claim from saying 1.2 to 1.6 g/kg/day is reasonable for many aging adults. The higher claim is less directly supported for general patients and crosses into a range where safety concerns become more relevant.

A 2016 narrative review in Food & Function stated that chronic intake above 2 g/kg/day may lead to digestive, kidney, and blood-vessel abnormalities, while also noting that 2 g/kg/day can be tolerated by healthy adults. The safety warning was based on a narrative synthesis rather than a systematic review, and the blood-vessel concern was not clearly defined. Reviews of kidney health in adults without chronic kidney disease generally find that higher-protein diets increase glomerular filtration rate, a measure of kidney filtering activity, without consistent lab evidence of kidney injury. Many trials are short, often six months or less, and tend to exclude higher-risk patients.

That distinction matters. In adults without chronic kidney disease, available randomized evidence does not show clear kidney damage from higher protein intake. In people with chronic kidney disease, the question changes. Meta-analyses of randomized trials in chronic kidney disease suggest protein restriction can reduce kidney failure events and slow decline in estimated glomerular filtration rate, a lab estimate of kidney filtering function. The benefit is clearest in advanced chronic kidney disease, and may be smaller or absent in moderate chronic kidney disease. It also varies by diabetes status, nutritional risk, adherence, and disease severity.

Protein source still matters

Long-term disease evidence is mostly observational, meaning researchers follow people's diets and outcomes rather than assigning diets. It cannot prove cause and effect. Still, it argues against treating all protein sources as equivalent. A 2020 dose-response meta-analysis of prospective cohort studies, which follow people over time, including 715,128 participants found that higher total protein intake was associated with lower all-cause mortality, meaning death from any cause. Plant protein was associated with lower all-cause and cardiovascular disease mortality. Other cohort analyses have found the opposite direction for total protein, including higher mortality associated with higher total protein, driven by animal protein and cardiovascular disease mortality.

For muscle outcomes, animal protein may have a small advantage for lean mass in some randomized trials, but direct animal-versus-plant comparisons are limited and the advantage is not consistent in older adults. If your goal is long-term health, the practical interpretation is not to chase protein grams with highly processed foods or large amounts of red and processed meat. The evidence is more compatible with meeting a moderate protein target using a mix of protein sources, including plant proteins and fish when those fit the rest of your diet.

What you can do with this

• If you are an older adult without chronic kidney disease, meaning long-term kidney damage or reduced kidney function, a daily intake around 1.0 to 1.6 grams per kilogram of body weight per day (g/kg/day) is better supported for muscle preservation than 0.8 g/kg/day, especially if you do strength training.
• If you are not strength training, the benefit of eating above the Recommended Dietary Allowance (RDA) is less certain under otherwise stable, non-stressed conditions.
• If your goal is strength or function, prioritize strength training. Higher protein may augment the response, but evidence does not support protein alone as a reliable way to build strength.
• If you have chronic kidney disease, diabetes with kidney involvement, heavy proteinuria, meaning high levels of protein in the urine, or a reduced estimated glomerular filtration rate, a kidney-filtering estimate, protein targets should be individualized because higher intake may conflict with kidney-protection strategies.
• Avoid assuming that more is better. The evidence base is strongest for moderate increases, not prolonged intakes above 2 g/kg/day.

For longer healthy aging, protein is best viewed as one input into muscle maintenance, preserving lean mass during weight loss, and frailty prevention. The defensible target is moderate, context-dependent, and tied to training status and kidney health. The evidence does not justify a universal high-protein mandate.