Short answer
Studies on muscle protein synthesis used single EAA doses of roughly 6.7 to 18 g, and daily amounts of 15 g (one study used 15 g three times a day). The ISSN suggests per-serving protein doses provide about 700 to 3000 mg of leucine. Follow the label, start low, and ask your doctor if you have a health condition.
Doses used in the studies we cite
EAA doses in published studies
| Study | Who | EAA dose | What was measured |
|---|---|---|---|
| Katsanos 2006 | Young and older adults | 6.7 g, single dose | Muscle protein synthesis; higher leucine share helped older adults |
| Dillon 2009 | Older women | 15 g a day, 3 months | Lean body mass up vs placebo |
| Børsheim 2008 | Older adults | 11 g EAA + arginine twice daily, 16 weeks | Lean mass, strength, function vs baseline |
| Tipton 1999 | Healthy volunteers | 13.4 g with sucrose, single dose | Net muscle protein synthesis |
| Ferrando 2010 | Older adults, bed rest | 15 g three times daily, 10 days | Muscle function |
| Volpi 2003 | Older adults | 18 g over 3 hours | Muscle protein balance |
| Drummond 2008 | Young and older men | 20 g after exercise | Muscle protein synthesis timing |
How to read your dose
Find total EAAs
Look for a line such as "EAA blend" or add up the nine amino acids. Ignore the scoop weight; it includes flavors and fillers.
Find leucine
Compare with the ISSN range of roughly 700 to 3000 mg per protein dose.
Check the balance
If BCAAs make up most of the grams, the other six are small. That may be fine, but it is not the same as a balanced EAA mix.
Compare servings, not scoops
Two products with a "1 scoop" serving can differ by several grams of EAAs.
Handy
- Digital food scale to check what a scoop really weighsFind it
Leucine: the number to check
The ISSN suggests protein doses provide about 700 to 3000 mg of leucine plus a balanced array of the other EAAs (ISSN 2017). In older adults, a 6.7 g EAA dose with 41% leucine (about 2.7 g) raised muscle protein synthesis, while the same dose at 26% leucine did not (Katsanos 2006).
Upper limits
There is no established upper intake level for most amino acids. In a study of five young men, blood ammonia rose above normal when leucine intake went above 500 mg per kg of body weight a day, about 35 g a day for an average man, which the authors proposed as a cautious upper limit (Elango 2012, Pencharz 2012). That is many times more leucine than any label serving. It does not apply to people with kidney or liver conditions, who should get advice first.
Next: when to take EAAs.
Questions people ask
How many grams of EAA should I take?
Studies used single doses of about 6.7 to 18 g. Many products serve 5 to 10 g per scoop. Follow the label, and do not exceed it without advice from a professional.
How much leucine should be in an EAA serving?
The ISSN position stand suggests protein doses containing about 700 to 3000 mg of leucine with a balanced array of the other EAAs. In older adults, a mix with a higher share of leucine worked better in one study.
Can you take too many EAAs?
There is no established upper limit for most amino acids. One study in young men found blood ammonia rose above normal at leucine intakes over 500 mg per kg per day, about 35 g a day, far above label doses.
Should I take EAAs once or twice a day?
Studies used one to three servings a day. The ISSN suggests spreading protein every 3 to 4 hours. Most labels suggest one or two servings.
Sources
- Katsanos et al., A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly, Am J Physiol Endocrinol Metab (2006)
- Dillon et al., Amino acid supplementation increases lean body mass, basal muscle protein synthesis, and IGF-I expression in older women, J Clin Endocrinol Metab (2009)
- Børsheim et al., Effect of amino acid supplementation on muscle mass, strength and physical function in elderly, Clin Nutr (2008)
- Tipton et al., Nonessential amino acids are not necessary to stimulate net muscle protein synthesis in healthy volunteers, J Nutr Biochem (1999)
- Ferrando et al., EAA supplementation to increase nitrogen intake improves muscle function during bed rest in the elderly, Clin Nutr (2010)
- Volpi et al., Essential amino acids are primarily responsible for the amino acid stimulation of muscle protein anabolism in healthy elderly adults, Am J Clin Nutr (2003)
- Drummond et al., Skeletal muscle protein anabolic response to resistance exercise and essential amino acids is delayed with aging, J Appl Physiol (2008)
- Jäger et al., International Society of Sports Nutrition position stand: protein and exercise, J Int Soc Sports Nutr (2017)
- Elango et al., Determination of the tolerable upper intake level of leucine in acute dietary studies in young men, Am J Clin Nutr (2012)
- Pencharz et al., Determination of the tolerable upper intake level of leucine in adult men, J Nutr (2012)
Last reviewed October 12, 2026. Formulas, labels and listings change; check the current label before you buy. This page is general information, not medical advice.