Three numbers that should move your breakfast
So how much does a single meal need to be worth? I have three findings, and the first one changes with age.
01 / Your Threshold Went Up
You need more per meal than you did at twenty-five. A pooled dose-response analysis found muscle protein synthesis plateaued at about 0.24 grams of protein per kilogram of body weight per meal in young men, and about 0.40 grams in men around seventy. For an eighty-kilogram man that is roughly 19 grams then against roughly 32 now, and some men in that data needed 0.6. Researchers call the underlying problem anabolic resistance, and a 2023 review argues much of it comes from inactivity and low protein rather than age alone.
02 / Leucine Is the Trigger, Roughly
You will see a leucine target quoted, and it deserves the caveat. Expert consensus recommends 25 to 30 grams of protein per meal carrying about 2.5 to 2.8 grams of leucine. A systematic review of 29 studies found 16 supported the leucine trigger idea and 15 did not, with the support concentrated in older adults, which is exactly who this letter is for. So take it as a rule of thumb whose best evidence happens to sit in your age group.
03 / Even Beats Skewed
You should spread it out. A crossover study in the Journal of Nutrition in 2014 fed the same total protein two ways, roughly 30 grams at each of three meals against 11, 16, and 63 grams. Twenty-four-hour muscle protein synthesis ran 25 percent higher on the even pattern. Note that this was eight people and a laboratory measurement rather than a year of body composition, so hold it as a strong hint rather than as proof.
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