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The Trommelen Study​

Is 30 grams of protein the maximum you can use in one meal? New research says no. Here's why.​

A new revelation about protein just dropped in the journal Cell (1). Let’s dig into it.

People always say, “The body can only use 30 grams of protein at once!” Is that true? Well, imagine eating a 16-ounce steak. If you can only use 30 grams of protein at once, you’ll find steak-shaped deposits in your toilet the next morning. That doesn’t happen. So, where does the steak go?

More protein helps build bigger muscles (2, 3, 4), but is there a limit to how much protein actually goes into your muscle tissue? It’s not a 100% efficient process because building muscle is a slow and labor-intensive process. Research from the same lab estimated that from a 20-gram scoop of whey protein, only 2 grams is directly deposited as protein in muscle tissue (5).

Dr. Jorn Trommelen set out to determine if there’s a limit to the amount of protein your body can absorb and use for muscle protein synthesis (MPS) or the process of stuffing amino acids into muscle tissue. He conducted tests on 12 healthy young men who consumed different amounts of a special milk protein at once. This protein contained tracer-labeled amino acids so the researchers could track them around the body and see where they ended up.

Dr. Jorn had a few speculations before the study began:

“It’s generally believed that only 20-40 grams of protein is effectively used for building muscle, with excessive amino acids being wasted as fuel (oxidation). I’m skeptical and hypothesize that the benefit of greater amounts of protein only becomes apparent when accounting for the prolonged digestion time required for a large dose.”

So, what actually happened?

After lifting, the subjects received either 25 grams of protein, 100 grams of protein, or a placebo. They performed a single bout of whole-body resistance exercise taken to failure. Then, they received four stable isotope amino acid infusions using intrinsically labeled milk protein. They took a bunch of blood samples and muscle biopsies over 12 hours.

Judging by this study, there doesn’t appear to be an upper limit to the body’s ability to absorb protein and synthesize muscle protein.

WHAT? That’s amazing!

In fact, consuming more protein led to an extended protein-digestion period, more amino acid absorption, and ongoing release into the bloodstream over the 12-hour period. Furthermore, there was a dose-response relationship: the group who consumed 100 grams of protein experienced the highest muscle protein synthesis rates.

So, we CAN use more protein at one time! But wait, there are a few details to cover.

While it’s true that the 100-gram protein group outperformed the 25-gram group in virtually everything, this was done after a brutal full-body workout consisting of 10 submaximal reps (a ramp-up) and then sets done at progressively increasing loads until failure.

What we don’t know is if this prolonged response in muscle protein synthesis would’ve continued after more than one workout. Most likely, yes, but to what degree with a 100-gram dose? We don’t know.

Remember, these subjects were young and healthy, with a robust response to protein intake. This response decreases with age (via anabolic resistance) and in some disease states (6), so if you’re older or have some pathology, these results may not apply.




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The amount of amino acids that subjects burned (oxidized) in the 100-gram dose was quite small. Less than 15% of the ingested protein was actually oxidized, supporting the conclusion that most of the protein was used to make muscles bigger. Score another one for more protein at once.

With just a single dose of 100 grams, they calculated that 13 grams (13% of the ingested protein) was incorporated into skeletal muscle tissue. While that seems small, comparatively, this is huge. This shows that skeletal muscle tissue has a much greater capacity to incorporate protein (amino acids) than we thought.

Now, you can walk out on a hypothetical limb and compare that to only 2 grams from four 20-gram doses, which clocks in at 8 grams of new muscle tissue. Thus, this 100-gram monster method would give you an extra 5 grams of muscle. Well, we don’t have the chronic data to support that idea yet. Maybe it is more; however, over time, my guess is that it won’t add up to massively more muscle.

Yes, this study also demonstrated that muscle connective protein synthesis rates were higher after ingesting 25 grams and 100 grams of protein. This indicates an anabolic response in connective tissue, too.

Connective protein synthesis rates were higher following the ingestion of 100 grams of protein compared to the placebo condition over the 12-hour post-feeding period, further supporting the impact of protein ingestion on collagen synthesis.

This matches some earlier work (7). In both cases, collagen as a substrate wasn’t given as there is other data showing that supplemental collagen may upgrade soft tissue changes (8-10). The takeaway? The other “connective tissue components” were also upregulated with only the milk protein given post-training.

The grand revelation from this study is this: if you’re planning to embark on an epic odyssey of fasting, it might be smart to load up on protein beforehand.

Now, here’s the pro from this study – you’ve got more flexibility when it comes to the frequency of your meals. But hold on tight because it means you’ll be chowing down on some serious protein portions if you choose to go the fewer meals route.

Don’t get bogged down in the details. The main idea is ensuring you’re getting that protein quota locked down each day. Current research shows around 0.7 grams per pound of body weight and possibly closer to 1 gram per pound of body weight if you’re really cutting calories (11-15). If you’re a 200-pound lifter, that clocks in at 140 grams of protein per day on the low end and 200 grams on the higher end.

By the way, this study also showed no changes in autophagy markers (recycling of used/misfolded proteins). So, eat more protein.

For this study, they investigated a milk protein that consisted of 20% rapid digestible whey protein and 80% slowly digestible casein protein, so you could speculate that a more prolonged anabolic response to protein ingestion is unique to it being slowly digestible.

A study published this year by the same group showed no difference between whey or casein when given before bed (17), so it’s unlikely that you’d see a huge difference with whey. Other protein sources would most likely provide a similar response, but the data is even more sparse there.

Here’s what Dr. David Church had to say:

"This study showed that muscle and whole-body protein metabolism can be increased with higher amounts of protein. That said, one of the main points is the length of the post-prandial (fed) period. It’s a ten-hour long period, and even then, the protein is still appearing in circulation as indicated by amino acid concentrations still elevated above baseline. Fewer but larger protein feedings throughout the day are just as effective as smaller doses spread evenly throughout the day. This is another strike against the idea of protein distribution being a large contributor to increases in muscle protein synthesis throughout the day.

This is great news since we now have data showing that you have more flexibility in how you distribute protein throughout the day. No, this doesn’t mean you should eat 100 grams of protein three times a day. However, it does provide valuable insights into how the body responds to protein intake and its potential benefits for optimizing muscle growth and recovery via a larger but more infrequent protein feeding.