You’ve heard there’s a limit and the rest gets wasted. A 2023 study went looking for that ceiling—and couldn’t find it!
By Jim Stoppani, Ph.D.
You’re at dinner and there’s a second chicken breast sitting on the platter. You want it. But somewhere in the back of your head is the rule you’ve heard a hundred times: your body can only use so much protein at once, and the rest gets wasted. So you leave it there.
I’ve been recommending 1.5-2 grams of protein per pound of body weight for a long time now, and I’ve taken plenty of heat for it. But the most common objection isn’t that high protein is dangerous, or that it’ll wreck your kidneys. It’s that same math argument: you can’t actually use that much, so why bother?
That objection deserves a real answer, because unlike a lot of the pushback I get, this one has actual research behind it.
So let’s go through it. Where that rule came from, what a 2023 study found when it went looking for the ceiling directly, and the three rules I’d put in its place.
Where The Idea Came From
Starting in the late 2000s, a series of well-run dose-response studies fed people increasing amounts of protein after a workout and measured muscle protein synthesis (MPS). They kept landing in the same place: somewhere around 20-25 grams of protein in one sitting maximized the MPS response, and larger doses didn’t push it higher.
That’s a real finding, and it’s been replicated. What followed was guidance—distribute protein evenly through the day, keep main meals around that 20-25-gram range, don’t waste the excess.
In the gym, that guidance drifted and the number got fuzzy. You’ll hear 20 grams. You’ll hear 30. You’ll hear 40 from someone who’s read a bit more. The figure depends on who’s talking, but the belief is always the same: there’s a ceiling, and past it you’re throwing protein away.
So is there? Here’s what I’d flag about the studies that produced that original number. They measured the response over a relatively short window—a few hours. If a small dose and a large dose both peak at about the same height inside that window, the large dose looks like it hit a wall.
Picture judging a fire by staring at it for five minutes. A small fire and a big fire both look lit. Come back six hours later and only one is still burning. That’s not a difference you can see in a five-minute look.
What hadn’t been done was looking at the long window with the right tools. Until 2023.
The Study That Went Looking For The Ceiling
A December 2023 study published in Cell Reports Medicine set out to test just how much protein the body can use after a workout. Led by researcher Jorn Trommelen, the study stands out because of its methodology. Stay with me here.
The researchers took 36 trained young men and put them through a 60-minute whole-body resistance workout. Immediately after, each subject drank a beverage containing either 0 grams, 25 grams, or 100 grams of protein.
And this wasn’t ordinary protein. The researchers produced specially labeled milk protein by giving a lactating cow traceable amino acids for four days; this allowed them to follow the protein from the drink into the bloodstream and muscle tissue.
Then they tracked it for 12 straight hours, with muscle biopsies at 4, 8, and 12 hours and blood draws throughout.
Here’s what they found…
The 100-gram dose produced a greater and more prolonged anabolic response than 25 grams—and it was still elevated at the 12-hour mark, when the measurement period ended. Not tapering. Still going.
And here’s the finding that answers the objection I opened with: The increase in amino acid oxidation—the process of burning amino acids for energy—was negligible compared with the increase in protein synthesis. In other words, the body wasn’t simply burning off all that additional protein. That assumption has long been central to the argument against larger protein doses, and it didn’t hold up here.
The authors’ conclusion was about as plain as research language gets: The body’s anabolic response increased with the size of the protein dose and lasted far longer than previously believed. Even at 100 grams, the researchers found no clear ceiling during the 12-hour study period.
What This Does And Doesn’t Change
I want to be careful here, because I’ve already watched people run way too far with this one.
This study does not say a single enormous meal is the optimal way to eat. It says a large dose isn’t wasted. Those are different claims!
Spreading protein throughout the day still makes sense, for reasons I’ll get to. It’s just not a plumbing problem where the tank overflows at gram 31.
So here’s what replaces the old rule:
Rule 1: Hit The Daily Number First
Of all the factors that affect how your body uses protein—when you eat it, how you divide it up, how much you get per meal, and which sources you choose—your total daily intake matters most. Nail that first. Everything else is fine-tuning.
If you should be eating 180 grams of protein a day but you’re only getting 120, debating whether to split it across four meals or five is pointless. Hit your daily number first, then decide how you want to spread it out.
For most hard-training lifters, that lands between 1.5 and 2 grams per pound of body weight. I’ve had hundreds of thousands of people run my programs at that intake, and it moves results more than any other variable. If you don’t know your number, I walk through how to calculate it on my site.
Rule take-home: Hit your daily protein intake goal consistently.
Rule 2: Stop Capping Meals That Don’t Need Capping
This is where the ceiling idea has done real damage.
I’ve watched lifters skip the second chicken breast, order the smaller steak, or take half a shake—actively eating less protein because they believed the rest would be wasted. Every one of those decisions makes it harder to hit the daily total that actually drives results.
If your schedule gives you three eating windows instead of six, put more protein in each one. If dinner is the meal where you can realistically get 70 grams, get 70 grams. That protein is going somewhere useful, and it’s going there for longer than we thought.
Rule take-home: Don’t eat less protein at a meal because you’re worried about exceeding a limit.
Rule 3: Why Spacing Still Matters
Here’s the reason spacing matters, and it has nothing to do with a ceiling. When you eat a high-protein meal, MPS spikes and then comes back down. Eat again too soon and you don’t get a second full spike, because the first one hasn’t finished. Wait too long and you spend that time in a net negative.
The research that best captures this fed trained men 80 grams of whey protein over 12 hours in three patterns: 10 grams every 90 minutes, 20 grams every 3 hours, or 40 grams every 6 hours. The middle pattern won. Areta and colleagues reported in the Journal of Physiology in 2013 that it produced 31-48 percent greater myofibrillar protein synthesis than either the frequent-small or the infrequent-large approach.
It’s worth noting what that study was and wasn’t measuring, since it gets used as evidence for a per-meal cap. It compared patterns, not doses—every group got the same 80 grams. This tells you how to space protein, but it says nothing about a limit.
Also note that they used fast-digesting whey. Whole food or a protein blend digests slower and keeps MPS elevated longer, so you can stretch that spacing further.
Rule take-home: Space meals to complete each MPS spike, not to stay under a limit.
Who This Changes The Most
If you’re over 40. As you age, your muscles become less responsive to protein, so it may take more per meal to produce the same muscle-building response. Larger servings help compensate for that. I’m in my fifties now, and I make sure I get at least 50 to 60 grams at every meal.
If you eat in a compressed window. A shorter eating window (ie, if you’re doing intermittent fasting/time-restricted eating) usually means fewer meals—and fewer meals mean you need more protein at each one to hit your daily target. You can’t impose a strict per-meal cap and still get enough protein for the day. In this case, the per-meal cap has to go.
If you’ve been skipping a shake because you “already had protein.” If it’s been a few hours, that’s a fresh spike, not a wasted scoop. A protein blend like Pro JYM or another quality blend covers a meal you’d otherwise miss, and blends keep the response elevated longer than straight whey.
My Take-Home Message
The idea of a hard per-meal protein limit stuck around because it gave people a simple rule to follow: Eat more than 25 or 30 grams at once, and the rest supposedly goes to waste. But the body doesn’t handle protein according to such a neat cutoff. A larger dose can produce a greater muscle-building response, the body keeps using that protein for hours afterward, and there’s little evidence the extra gets burned off.
So don’t push away that second chicken breast because you think your body can’t use it. Your bigger priority is getting enough protein over the course of the day.
Know your daily protein number. Then make sure you hit it.