Protein: How Much Do You Really Need?

Quick Takes

The short answer: It depends on your age, activity level, and goals—and the truth is more interesting than you think.

• For older adults (65+): Around 1.2 g/kg/day preserves muscle mass, even without exercise

• During weight loss: Significantly higher protein (1.6–2.4 g/kg/day) protects against muscle loss

• The longevity paradox: Lower protein may extend lifespan in middle age, but higher protein protects function in older age

• Plant vs. animal: Vegans need more total protein (1.3–1.6 g/kg/day) to match the muscle-building effects of omnivorous diets

• Exercise changes everything: Active people can maintain muscle on less protein than sedentary individuals

The twist: The 0.8 g/kg recommendation—the standard since the 1980s—may optimize longevity pathways in middle age but falls short for preserving strength and independence as we age.

Favorite Finds

Want to get a handle on your actual protein intake and muscle mass? Here are my go-to tools:

Cronometer – The most accurate nutrition tracking app I've found. Unlike other apps that rely on crowdsourced data, Cronometer pulls from verified databases (USDA, NCCDB). It breaks down your amino acid profile, tracks micronutrients, and makes it easy to see if you're hitting your protein targets across meals. The free version is excellent; the premium version adds biometric tracking and detailed reports.

BodySpec DEXA Scan – If you're serious about understanding your body composition, skip the bathroom scale and get a body composition DEXA scan. There are locations across the US and they provide precise measurements of muscle mass, bone density, and fat distribution. You'll get your actual appendicular skeletal muscle mass (the arms and legs muscle that matters most for function) rather than rough estimates. Around $60-70 per scan, and you can track changes over time.

The fasting-mimicking diet: a way to stimulate autophagy, by incorporating a 2-4 cycles into your year.

Deep Dive: The Protein Paradox

The Foundation: What Older Adults Need

First a disclosure: Unlike just about all other influencers, I am not making money from consulting on or advertising any energy bars or processed foods or special diets. I don’t have any conflicts of interest other than the fact that I personally prefer an omnivorous (gluten-free) diet.

The baseline recommendation of 0.8 g/kg/day was established as the minimum to prevent deficiency in younger adults—but it is demonstrably inadequate for maintaining muscle and function as we age.

Research on older adults consuming 1.2 g/kg/day or more for 12 weeks while maintaining normal activity showed significantly improved appendicular (arm and leg) skeletal muscle mass compared with those consuming 0.8 g/kg/day (Kim & Park, 2020). This wasn't a strength training study—this was simply eating more protein during everyday activity.

A randomized dose-response trial tested three levels of protein intake (0.8, 1.2, and 1.5 g/kg/day) in elderly adults aged 70–85 over 12 weeks (Park et al., 2018). The results were stark: the 1.2–1.5 g/kg/day groups maintained or increased lean mass and muscle function, while the 0.8 g/kg/day group lost muscle. This is the average level of protein consumed by older people. Please measure yours!!

These findings led the European Society for Clinical Nutrition and Metabolism (ESPEN) to recommend 1.0–1.2 g/kg/day for healthy older adults and 1.2–1.5 g/kg/day for those at risk of muscle loss or frailty (Deutz et al., 2014).

The Weight Loss Complication

If you're cutting calories to lose weight, the protein equation changes dramatically—and the research here is unambiguous.

In a landmark controlled trial, healthy adults on a 40% calorie deficit consumed either 1.2 g/kg or 2.4 g/kg of protein daily while doing resistance and interval training (Longland et al., 2016). The high-protein group actually increased lean mass despite the severe energy deficit, while the 1.2 g/kg group lost some lean tissue.

Another metabolic study put subjects on a 40% energy deficit with diets supplying 0.8, 1.6, or 2.4 g/kg/day for three weeks (Pasiakos et al., 2013). Both the 1.6 and 2.4 g/kg groups retained significantly more lean mass and preserved muscle protein synthesis compared with the 0.8 g/kg group.

In female recreational athletes on calorie restriction, only those on high-protein intake avoided muscle loss and maintained exercise capacity, whereas standard-protein groups lost muscle (Hiroux et al., 2023). MOST women consume under 0.8g/kg of protein.

The picture becomes more challenging with age. In older adults undergoing weight loss, higher dietary protein (up to 1.3–1.5 g/kg/day) reduced but did not fully prevent lean tissue loss (Beavers et al., 2019). The authors concluded that maintaining muscle mass during caloric restriction likely requires both higher intakes and resistance training.

The Longevity Paradox: When Less Might Be More (Sort Of)

Here's where it gets genuinely interesting: some compelling evidence suggests that lower protein intake in middle age may actually extend lifespan—but the story is far more nuanced than it first appears.

A large U.S. cohort study found that adults aged 50–65 with high protein intake had a 75% greater overall mortality and a four-fold increase in cancer mortality, largely due to higher IGF-1 signaling, which drives cell growth and reduces autophagy (Levine et al., 2014). But here's the critical twist: above age 65, the association completely reversed—higher protein intake correlated with lower mortality and cancer risk as protein needs rise with anabolic resistance.

Research on nutrition and longevity shows that lower protein intake, especially when substituting plant for animal proteins, is associated with longer telomeres, reduced IGF-1 levels, and slower biological aging (Ekmekcioglu, 2020).

The mechanism: The debate centers on nutrient-sensing pathways like mTOR and IGF-1. Chronic overstimulation of these pathways (from sustained high protein intake, especially animal sources) may accelerate cellular aging and cancer risk. The body's repair mechanisms—particularly autophagy, the cellular "cleanup" process—are suppressed when mTOR is constantly activated.

The counterargument: For older adults, anabolic resistance and sarcopenia (very low muscle mass, not uncommon) shift priorities. Maintaining muscle and metabolic function generally requires ≥1.2 g/kg/day, even if it means modest mTOR signaling increases. The biological priorities literally change with age—what might extend lifespan at 55 could impair function at 75.

The sweet spot: Some researchers propose a balanced pattern—moderate protein pulses interspersed with fasting or caloric restriction—that optimizes both longevity and function through controlled mTOR engagement. The goal is transient mTOR activation (promoting regeneration) with sufficient autophagy intervals (promoting longevity).

The Exercise Exception: When You Need Less

Here's a fascinating wrinkle that threads through all of this research: exercise fundamentally changes how much protein you need.

Older adults experience increased anabolic resistance, requiring more protein to preserve nitrogen balance and functionality (Deutz et al., 2014). However, the ESPEN expert group emphasized tailoring intake to physical activity—noting that exercise sensitizes muscle to dietary amino acids, allowing lower optimal intakes compared to sedentary peers.

Research in very old adults found that while 1.6 g/kg/day optimizes muscle preservation, the interaction between physical activity and protein intake allows some individuals to maintain functional muscle with less dietary protein if exercise is robust and consistent (Franzke et al., 2018). They describe a gradient of need from 0.8 g/kg in active, highly anabolic individuals to >1.2 g/kg in sedentary or frail individuals.

The mechanism: Age-associated "anabolic resistance" stems from reduced sensitivity of the IGF-1/Akt/mTOR pathway to amino acids (Barclay et al., 2019). Exercise upregulates this pathway independently, compensating for lower protein intake. People who regularly activate these cascades through resistance or endurance activity can achieve equivalent anabolism at lower dietary loads.

The implication: There's an individualized inflection point—usually midrange protein intake (roughly 1.0–1.3 g/kg if active, up to 1.6 g/kg if inactive)—that produces sufficient anabolic signaling without continuous mTOR hyperactivation.

Plant vs. Animal Protein: Not Created Equal

If you're following a vegan diet, the protein story gets more complex—but not insurmountable.

Plant proteins have less favorable amino acid profiles and reduced digestibility, leading to lower muscle protein synthesis per gram compared to animal proteins (Reid-McCann et al., 2022). This can become clinically relevant in older adults due to anabolic resistance, suggesting higher total protein or blended sources are needed to match animal-protein outcomes.

But when protein intake is optimized, the differences disappear. In a 10-week resistance-training trial, adults consuming 2 g/kg/day of either vegan or omnivorous high-protein diets showed identical muscle hypertrophy and strength gains (Monteyne et al., 2023). When total protein and essential amino acids are optimized, vegan diets can elicit equal anabolic adaptation during high-protein feeding.

Cross-sectional studies of older vegans show mixed findings: some observational cohorts suggest vegan or vegetarian elderly may exhibit slightly lower grip strength on average, but this is attributable to lower total protein and energy intake—not veganism per se.

The practical implication:

• For omnivores: 1.0-1.2 g/kg/day usually preserves lean mass

• For vegans: 1.3–1.6 g/kg/day, distributed evenly across meals with at least 2.5 g leucine per meal, better compensates for lower bioavailability

• Exercise increases amino acid utilization efficiency, reducing the differential between plant and animal sources

So What Should You Actually Do?

The research reveals no single answer, but rather a framework for personalization:

If you're middle-aged (50–65) and prioritizing longevity: Consider moderate protein (0.8–1.0 g/kg/day), emphasizing plant sources, combined with regular resistance training and potentially periods of fasting-mimicking (see Favorite Finds). This may optimize mTOR/IGF-1 balance for long-term health while exercise preserves muscle.

If you're older (65+) and prioritizing function: Aim for 1.2–1.5 g/kg/day to counter anabolic resistance and preserve independence. The longevity concerns that apply to middle age appear to reverse in older adults.

If you're losing weight at any age: Increase protein substantially (1.6–2.4 g/kg/day) to protect muscle mass, and include resistance training if possible.

If you're very active with regular resistance training: You can likely maintain muscle at the lower end of these ranges (0.8–1.2 g/kg/day depending on age).

If you're eating plant-based: Add approximately 0.2–0.4 g/kg/day to the recommendations above, distribute protein evenly across meals, and ensure adequate leucine (2.5 g per meal means you will have to combine legumes with soy, or use soy protein powder).

The "optimal zone" balances transient mTOR activation (promoting regeneration) with sufficient autophagy intervals (promoting longevity). Your personal inflection point depends on your age, activity level, body composition, metabolic health, and whether you prioritize maximum lifespan or maximum healthspan.

Track your actual intake with tools like Cronometer. Verify your muscle mass with DEXA scans every 6–12 months. Read experts with a modicum of humility, who understand nuance. Adjust based on results, not assumptions..

References

Barclay, R. D., Burd, N. A., Tyler, C., Tillin, N. A., & Mackenzie, R. W. (2019). The role of the IGF-1 signaling cascade in muscle protein synthesis and anabolic resistance in aging skeletal muscle. Frontiers in Nutrition, 6, 146.

Beavers, K. M., Walkup, M. P., Weaver, A. A., Huffman, K. M., Johnson, J. L., Nicklas, B. J., Ding, J., Demons, J. L., Chaves, P. H. M., & Marsh, A. P. (2019). Effect of exercise modality during weight loss on bone health in older adults with obesity and cardiovascular disease or metabolic syndrome: A randomized controlled trial. Aging and Disease, 10(6), 1456-1467.

Deutz, N. E., Bauer, J. M., Barazzoni, R., Biolo, G., Boirie, Y., Bosy-Westphal, A., Cederholm, T., Cruz-Jentoft, A., Krznariç, Z., Nair, K. S., Singer, P., Teta, D., Tipton, K., & Calder, P. C. (2014). Protein intake and exercise for optimal muscle function with aging: Recommendations from the ESPEN Expert Group. Clinical Nutrition, 33(6), 929-936.

Ekmekcioglu, C. (2020). Nutrition and longevity—From mechanisms to uncertainties. Critical Reviews in Food Science and Nutrition, 60(18), 3063-3082.

Franzke, B., Neubauer, O., Cameron-Smith, D., & Wagner, K. H. (2018). Dietary protein, muscle and physical function in the very old. Nutrients, 10(7), 935.

Hiroux, C., Vandoorne, T., Koppo, K., & Van Thienen, R. (2023). High versus low dietary protein during energy restriction: Impact on body composition and exercise performance in recreational female athletes. Frontiers in Nutrition, 10, 1089122.

Kim, D., & Park, Y. (2020). Amount of protein required to improve muscle mass in older adults. Nutrients, 12(6), 1700.

Levine, M. E., Suarez, J. A., Brandhorst, S., Balasubramanian, P., Cheng, C. W., Madia, F., Fontana, L., Mirisola, M. G., Guevara-Aguirre, J., Wan, J., Passarino, G., Kennedy, B. K., Wei, M., Cohen, P., Crimmins, E. M., & Longo, V. D. (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 Metabolism, 19(3), 407-417.

Longland, T. M., Oikawa, S. Y., Mitchell, C. J., Devries, M. C., & Phillips, S. M. (2016). Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: A randomized trial. American Journal of Clinical Nutrition, 103(3), 738-746.

Monteyne, A. J., Coelho, M. O. C., Murton, A. J., Abdelrahman, D. R., Blackwell, J. R., Koscien, C. P., Knapp, K. M., Fulford, J., Finnigan, T. J. A., Dirks, M. L., Stephens, F. B., & Wall, B. T. (2023). Vegan and omnivorous high protein diets support comparable daily myofibrillar protein synthesis rates and skeletal muscle hypertrophy in young adults. Journal of Nutrition, 153(6), 1680-1695.

Park, Y., Choi, J. E., & Hwang, H. S. (2018). Protein supplementation improves muscle mass and physical performance in undernourished prefrail and frail elderly subjects: A randomized, double-blind, placebo-controlled trial. American Journal of Clinical Nutrition, 108(5), 1026-1033.

Pasiakos, S. M., Cao, J. J., Margolis, L. M., Sauter, E. R., Whigham, L. D., McClung, J. P., Rood, J. C., Carbone, J. W., Combs, G. F., Jr., & Young, A. J. (2013). Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: A randomized controlled trial. FASEB Journal, 27(9), 3837-3847.

Reid-McCann, R. J., Brennan, S. F., McKinley, M. C., & McEvoy, C. T. (2022). The effect of animal versus plant protein on muscle mass, muscle strength, physical performance and sarcopenia in adults: Protocol for a systematic review. Systematic Reviews, 11(1), 64