Quick answer: Protein builds and repairs tissue, forms enzymes, hormones and antibodies, and transports molecules like oxygen. Animal proteins are complete and highly bioavailable; plant proteins can be combined to cover all essential amino acids. Needs vary with age, activity and health. Choose pasture-raised meat, wild-caught fish, eggs and nutrient-dense organ meats in moderation.
Key takeaways
Protein is the raw material for muscle, skin, collagen, enzymes and hormones.
Animal proteins are complete and well absorbed, and plant proteins can be combined to cover the essential amino acids.
Older adults and active people often need more protein, and pairing it with strength training can help preserve muscle as you age.
What protein does
Growth and repair
Muscle, skin, hair and nails all rely on protein.
Structure
Collagen gives strength to skin, tendons and ligaments.
Enzymes and hormones
Enzymes drive digestion and metabolism; insulin and growth hormone are proteins.
Immunity and transport
Antibodies are proteins, and hemoglobin carries oxygen.
Protein quality
Animal proteins contain all essential amino acids and are well absorbed. Plant proteins may be lower in some amino acids, but combining sources covers them.
How much protein?
Needs depend on age, activity and health; older adults and active people often need more. People with kidney disease should follow their doctor’s advice. These ranges are general education, not a prescription; personalize them with your provider.
What protein to eat
Good protein choices include pasture-raised beef, lamb, pork and poultry, wild-caught fish and seafood, and pasture-raised eggs. Organ meats such as liver fit too, in moderation because of their high vitamin A. See more in foods to eat.
Healthy aging lens
Muscle protects metabolism and independence with age; protein plus strength training can help preserve it. See strength training.
What the research shows
Protein research focuses on how much people need and on how protein-rich, whole-food patterns compare with standard diets.
How much protein supports muscle (Morton 2018, meta-analysis of 49 trials). This review pooled 49 randomized trials with 1,863 healthy adults doing resistance training for at least 6 weeks. Extra protein added about 0.3 kg of lean mass and 2.5 kg to one-rep max strength, and gains leveled off at a total intake of about 1.6 g of protein per kg of body weight a day. A limitation is that these were healthy adults who lifted weights, not people following keto or fasting specifically.
A two-year Paleo-style trial (Mellberg 2014, randomized trial). 70 postmenopausal women with obesity ate either a Paleolithic-type diet or a diet following Nordic nutrition guidelines, without calorie limits, for 2 years. The Paleo group lost more fat at 6 months (6.5 kg vs. 2.6 kg), but by 24 months the difference was no longer significant (4.6 kg vs. 2.9 kg); triglycerides stayed lower with Paleo. A limitation is that women in the Paleo group did not reach their protein targets, so adherence was incomplete.
Strength of the evidence: Moderate-quality evidence supports getting enough protein, especially with strength training, but the ideal amount varies with age, activity and kidney health.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if you have a chronic inflammatory, autoimmune or digestive condition, or if you have diabetes, kidney disease or take medications affected by diet changes. The same is true if you are pregnant, breastfeeding, or have a history of disordered eating, or if you want a plan tailored to your labs, symptoms and goals.
See a medical provider promptly for severe abdominal pain, signs of an allergic reaction such as swelling or trouble breathing, or fainting.
Want an anti-inflammatory eating plan built for you?
A free 15-minute consultation with Dr. Kneessi. No cost, no obligation. In-office in Odenton, MD or by telehealth.
Questions to bring to your clinician
These questions can help you get the most out of your next visit.
How much protein do I need, and is there any reason, such as kidney health, to be careful?
How much protein should I aim for each day, given my age and activity?
Which protein sources would fit an anti-inflammatory diet and my tastes?
Do any of my health conditions change how much protein I should eat?
Frequently asked questions
How much protein do I need?
It varies with age, activity and health.
Is animal protein better than plant protein?
Animal proteins are complete; plant proteins can be combined.
Are organ meats healthy?
They’re nutrient-dense; eat liver in moderation.
Can too much protein be harmful?
People with kidney disease may need to limit it.
Sources
- Berrazaga I, et al. The Role of the Anabolic Properties of Plant- versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review. Nutrients 2019. PMID: 31394788. https://pmc.ncbi.nlm.nih.gov/articles/PMC6723444/
- Bauer J, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc 2013. PMID: 23867520. https://pubmed.ncbi.nlm.nih.gov/23867520/
- Penniston KL, Tanumihardjo SA. The acute and chronic toxic effects of vitamin A. Am J Clin Nutr 2006. PMID: 16469975. https://pubmed.ncbi.nlm.nih.gov/16469975/
- Morton RW, 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 in healthy adults. Br J Sports Med 2018. PMID: 28698222. https://pmc.ncbi.nlm.nih.gov/articles/PMC5867436/
- MedlinePlus: Dietary Proteins
- MedlinePlus: Nutrition
- Morton RW, 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 in healthy adults. Br J Sports Med 2018. PMID: 28698222. https://pubmed.ncbi.nlm.nih.gov/28698222/
- Mellberg C, et al. Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial. Eur J Clin Nutr 2014. PMID: 24473459. https://pubmed.ncbi.nlm.nih.gov/24473459/
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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