Protein Myths, Debunked by the Evidence

What the evidence says

In people with healthy kidneys, high protein intakes (up to ~2.2 g/kg/day and beyond) have not been shown to cause harm in long-term studies. The concern is real only for people with pre-existing kidney disease, who should follow their doctor's guidance. A 2018 review in the Journal of Nutrition found no adverse effect of high protein on kidney function in healthy individuals. If you have kidney disease, this myth becomes a real caution — talk to your clinician.

What the evidence says

This confuses two different things. Your body absorbs essentially all the protein you eat. What is limited is how much of a single meal drives muscle protein synthesis at once — roughly 0.3–0.4 g/kg, or 20–40 g for most adults. The rest is still used: for tissue repair, enzyme production, immune function, and energy. So a 60 g dinner isn't 'wasted,' it's just less optimal for muscle building than splitting it. Absorption and muscle synthesis are not the same.

What the evidence says

Most plant proteins are lower in one or more essential amino acids, but you don't need every amino acid in every bite — you need them across the day. Combining legumes (beans, lentils) with grains (rice, wheat) over a day gives a complete amino acid profile. Soy, quinoa, and hemp are complete on their own. Studies show trained vegans and vegetarians build muscle at rates similar to omnivores when total protein and leucine are matched. The calculator's +10% vegan adjustment accounts for the lower digestibility.

What the evidence says

Muscle protein synthesis saturates at roughly 1.6–2.2 g/kg/day for most people. Beyond that, extra protein provides diminishing returns for muscle — it's either oxidized for energy or, if it pushes you into a calorie surplus, stored as fat. Very high intakes (3+ g/kg) are used by some bodybuilders but mainly displace other nutrients and add cost without clear benefit. More is not better once you've met the optimal range.

What the evidence says

This is the outdated 'acid-ash hypothesis,' and it has been debunked. Modern research shows higher protein intake is actually associated with better bone health and a lower fracture risk, partly because protein increases calcium absorption and supports muscle mass (which protects bones). The key is getting enough calcium and vitamin D alongside protein. Protein does not weaken healthy bones.

What the evidence says

The window is far wider — roughly 1–2 hours before to 1–2 hours after training. A 2013 meta-analysis by Schoenfeld found that, when total daily protein is matched, the timing of the post-workout meal has a small effect. What matters is having amino acids available around the session, not the exact minute. If you eat 3–4 protein meals a day, one will naturally land near your workout.