Dietary Protein

In about 80% of the pooled trials people were already eating at least 1.2 g per kg a day, so this measures going from enough to more, not from too little to enough. The 1.62 figure comes with a range running from 1.03 to 2.20, wide enough to be a region rather than a line. Most trials ran six to twelve weeks. Effects shrank with age and were larger in people already training.

A null result is harder to establish than a positive one, and this one carries the weight of the finding. Strength was pooled across one-rep-max tests, isometric tests and handgrip, which do not always move together. The spline curves are smooth in a way the underlying trials are not. The search covered two databases.

Expressed per kilo of whole body mass, the widely quoted 0.40 against 0.24, the same comparison reached only p = 0.055. This pools data from studies run earlier for other purposes rather than a trial built for the question. Men only, in both age groups. It measures a building rate over hours, not muscle held onto over years.

A position stand grades existing literature and computes no pooled estimate of its own, so these ranges are considered judgements rather than measurements. The society receives industry support and several authors declare commercial ties to supplement companies, which is worth weighing against recommendations that favour supplementing. It was published in 2017, before the large-bolus work and before trials that compared timings head to head.

One acute recovery period with a tracer, not muscle measured over a training block. Thirty resistance-trained men, no women and no older adults. Only 20 g and 40 g were compared, so this shows the per-meal ceiling is above 20 g without showing where it is. The advantage of 40 g over 20 g was real but small, 0.059 against 0.049 percent per hour.

Only the immediate before-versus-after contrast has been tested this way; nobody has randomised protein eaten hours from training. The direct-comparison review had five studies to work with, and in it lower-body strength did favour eating beforehand at p = 0.048, before the subgroup test declined to confirm it. The ten-week trial had 21 men, too few to prove equivalence. The author group behind two of these is publicly associated with the position they support.

The randomised evidence applies only to people whose kidneys were healthy at the start, and early kidney disease is common and silent. Diet in the cohort came from food frequency questionnaires, which are imprecise, and its top quartile is a moderate Korean intake rather than a deliberate high-protein diet. In the cohort, a rapid decline meant the estimated filtering rate falling by more than 3 mL a minute each year, a research threshold rather than a diagnosis of kidney disease. In a sixteen-week trial at 3.2 g per kg a day, kidney and liver markers rose within the high-protein groups even though the comparison between groups came out level.

Short trials show filtration rising without declining; a long cohort saw a signal but read kidney function off creatinine, which protein itself raises. Nothing here shows harm, and nothing establishes safety over decades.

All four are acute tracer studies in young trained men, measuring a building rate over hours rather than muscle held onto over months, and the two do not always track. The original plateau rests on telling a 20 g response apart from a 40 g one in six people. The 100 g result comes from a four-tracer method used by very few laboratories. Nobody tested whether the same protein split across the day would do as well.

A 20 g per-meal ceiling shows up four hours after a one-leg session and not twelve hours after whole-body work, so it belongs to the measurement. No trial has fed large doses for months and weighed the muscle kept.