Newsletter #295

For years now, we’ve been told that we need to spread out our protein intake across the day in multiple meals.

But why? There are two reasons for this.

One factor is often referred to as the anabolic ceiling. The idea is that our capacity to use dietary protein for muscle rebuilding is acutely maxed out at a dose of around 20-25g, and anything above this threshold is instead oxidized. This has some obvious implications for protein distribution and utilization. If, for example, you consume 60 grams of protein at dinner, you are in effect wasting more than half of that protein, versus if you had split it in half and eaten it on two separate occasions.

Another reason is the anabolic window. If you've been involved with the fitness scene for a while, you already know what this is about. The thinking here is that there is a short time right after training when your muscles are repairing themselves and are more receptive to taking up amino acids. Accordingly, if you consume protein within an hour after your workout, your recovery will ostensibly be greater, with more gains as a result.

So, to summarize, the standard dogma states that we can only utilize a limited amount of protein at a given meal for muscle protein synthesis, and our ability to use protein for that purpose is substantially greater immediately after training.

But what if neither point is true at all?

That is what a remarkable new study seems to suggest.

Before I dive into the details of this research, I’d like to quickly suggest that you consider becoming a humanOS Pro member. An annual membership is just $7.99 per month, granting you access to all of our programs, educational content, recipes, etc. Plus, it’s the best way to support the work that we continue to do here every single week. :)

Okay, now, without further ado…

Prior research has suggested that post-workout muscle protein synthesis is maxed out at an intake of around 25 grams of protein. However, these studies have only assessed responses to moderate doses of protein in humans, measured over a few hours after ingestion. Could we learn more about how the body handles protein by tracing it over a much longer timespan, and comparing much larger doses of protein?

To address this question, researchers in Maastricht administered amino acids with tracers to a dairy cow, which then generated milk with labeled amino acids incorporated into its protein matrix. The Dutch scientists used this milk to produce a special protein powder whose amino acids would be readily distinguishable in the blood and that could, in effect, be followed as it circulated through the body.

From there, they selected 36 healthy young men and divided them into three groups:

They put the guys through what sounds like a decently formidable resistance workout: four sets of 10 reps of leg press, leg extension, lat pulldown, and chest press. The working sets were done at 80% of their 1-rep max, and the men performed these exercises "under strong verbal encouragement." Then, everyone consumed their assigned supplement.

So far, this study resembles prior studies that examine the relationship between protein intake and muscle protein synthesis. But here is where it diverges: the researchers then assessed the metabolic fate of the amino acids they had consumed for the next 12 hours. To that end, they performed four muscle biopsies and collected 12 blood samples.

Doesn’t sound too fun for the participants. But as it turned out, this unpleasant-sounding methodology was revelatory. Let's look at what they found.

The researchers wanted to answer a couple questions here, which relate to one another: When people consume very large doses of protein, what happens to all of those amino acids? And how much of that protein can be utilized at any given time for muscle protein synthesis?

The blood sampling showed, unsurprisingly, that plasma amino acid concentrations were higher in those who consumed protein compared to placebo. Specifically, amino acid levels were higher for five hours after ingesting 25 g of milk protein. Consuming 100 grams of protein, however, elicited a greater increase in plasma amino acids, and they remained higher for the full 12-hour monitoring period.

So, a larger acute dose of protein means not just a bigger boost in amino acids in circulation, but they also hang around in the blood for much longer. What happens to them from there?

As we mentioned before, it has previously been surmised that when you consume “excess” protein beyond the hypothetical anabolic ceiling, the extra amino acids are broken down and used for energy like other macronutrients (or perhaps excreted). However, these researchers determined that the high protein load did not lead to a disproportionate rise in amino acid oxidation. In fact, less than 15% of ingested protein was oxidized. In other words, most of the amino acids that you take in ultimately do get used. And that brings us to the question of the anabolic ceiling.

The researchers found a clear dose-response relationship between total protein ingested and muscle protein synthesis. Over the course of the 12-hour postprandial period, incorporation of the amino acids from the milk protein increased in a linear fashion, and the difference between the two protein groups became more pronounced as time progressed. Between 4-12 hours after consuming the protein, the muscle protein synthesis rate was 40% higher in the 100g group, compared to the 25g group.* This explains why previous trials have failed to find a difference in muscle protein synthesis in larger doses – they didn't take measurements for long enough!

As the researchers summarize, "the anabolic response to protein ingestion has no apparent upper limit in magnitude and duration in vivo in humans."

So, the key takeaway here is that it may not really matter when you consume your protein, or how it's distributed across the day, which allows for far more flexibility in how we eat and simplifies diet planning. (No need to bring protein shakes with you to the gym). It's also encouraging news for those of you out there who rely upon time-restricted feeding regimens.

One small caveat worth considering here relates to the characteristics of these participants. Everyone was young, healthy, and "recreationally active." We know that the anabolic response to dietary protein is blunted in older adults, meaning that a given dose of protein does not stimulate muscle protein synthesis to the same degree in older people as it does in younger counterparts. Furthermore, habitual physical activity seems to enhance sensitivity of skeletal muscle tissue to the uptake of amino acids. Accordingly, you’d kind of want to see if the apparent flexibility of the anabolic window, as demonstrated in this study, also applies to older adults, and/or inactive individuals.

*Another novel finding here was an increase in muscle connective protein synthesis rates, which was more pronounced in the 100g group than the 25g group. This has not been previously seen in studies using dairy protein, and is often presented as being a unique advantage of collagen peptides.

🌡️ In the Victorian era, leeches were used to try to predict the weather.

In the days before we could develop forecasts using radar and satellites, the sudden changes in weather patterns must have seemed senseless and terrifying. Not to mention an ongoing threat to travelers and farmers.

British doctor and inventor George Merryweather wondered if it might be possible to harness the sensitivities of other creatures to pick up on atmospheric phenomena that elude our own senses. To that end, he developed a contraption which he dubbed the “Tempest Prognosticator.” Twelve leeches were kept in small bottles within the device. When they would become agitated due to oncoming storms, they would crawl upward within the bottles, causing bells to ring.

The device never really took off, perhaps due to practical issues, i.e. the unpleasant reality of keeping leeches. I keep wondering if Merryweather’s colleagues were pleading with him to find literally anything other than a blood sucking worm to fulfill this particular role.

Merryweather seems to have viewed the critters with great affection. He referred to the leeches as his "jury of philosophical councilors." He also said that the bottles were placed in a circle so that his "little comrades" could see each other and "not endure the affliction of solitary confinement."

We've tried a lot of protein powders. A lot. And we each have our own preferences, of course. But to try to find a consensus favorite, we actually did blinded taste testing with a group of subjects. This product was voted best overall, across a group of about 40 different products. Highly recommended. 👊

This week, in light of the new year (and our focus on protein here), we’d like to highlight another course from the Ideal Weight Program, developed by our good friend Stephan Guyenet, a researcher who specializes in the neuroscience of eating behavior and obesity.

The Ideal Weight Program is an evidence-based system for sustainable weight management which teaches you the science of body weight regulation and eating behavior, and translates it into simple, practical strategies for weight management. This program offers three different diets based on your weight management goal. For those who need to lose body fat relatively rapidly (but safely), the FLASH Diet is the plan for you.

FLASH stands for Fat Loss and Sustainable Health, and is modeled after protein-sparing modified fast diets that were developed by researchers in the 1970s and remain the most effective fat loss plan ever studied. In this course, Stephan explains the background behind the FLASH diet, what to eat and how to prepare food to adhere to this plan, and more.

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