In last week’s newsletter, we covered what protein does for a runner and how much you should target each day. If you haven’t read it, I’d recommend starting there.
This week, we’ll dive into a few more of the most asked questions in sports nutrition about protein intake.
My usual disclaimer. I have researched these topics deeply, but I’m not a registered dietitian. If you have specific questions or are looking for individualized guidance, meeting with am RD is a great idea.
Is it better to consume a protein supplement or a whole food source of protein?
I love protein bars. I grew so fond of them at the end of my freshman year that on a daily basis I grabbed an extra bar from the nutrition center in our gym until I had a stockpile of about 50, which I then flew across the country for summer vacation. They tasted like candy, and I told myself I could eat as many as my protein requirements demanded.
Eventually, it dawned on me that these treats were probably nothing more than candy bars fortified with enough whey isolate to pass as performance nutrition products. After that, I mostly switched to hard-boiled eggs, Greek yogurt, and chocolate milk.
So was my guilty pleasure helping or hurting?
Once total protein, essential amino acids, energy, and training demands are matched, there’s no evidence that supplemental protein like whey beats whole food for muscle repair, overnight recovery, or long-term adaptation. Researchers use powders because they standardize variables, not because they work better. Protein isolates allow you to measure an acute response without fats, fiber, and other foods confounding the signal.
In my research, I found that sports nutrition experts generally prefer whole foods over protein isolates. This is because whole foods bring micronutrients, vitamins, and fiber along with the protein.
Protein bars should be considered convenience tools, useful if you have a hectic schedule or cannot sit down for a meal.
Practical takeaway: Commit to a “food-first” approach. Build your meals around complete whole proteins (eggs, dairy, fish, poultry, tofu, legumes) and keep powders and bars as backups for when you’re in a pinch.
Animal vs plant protein: does the source matter?
The main difference between animal and plant proteins comes down to essential amino acids. These are nine amino acids the body cannot make on its own, so they have to come from food. The rest, called non-essential amino acids, your body can build on its own.
The persistent claim is that plant proteins are “incomplete,” missing certain essential amino acids entirely. That isn’t true. The real differences are in distribution and digestibility. Plant proteins carry proportionately less of certain essential amino acids. For example, grains run low in lysine, and legumes are deficient in methionine and cysteine. The fibrous cell walls of whole plant foods also reduce how much you can absorb.
For endurance athletes, the sheer volume of food required to cover their total energy expenditure tends to wash out those limitations. And while plant protein has lower anabolic potential than animal protein at equal small doses, a larger dose can close the gap.
One study gave 60 men one of five protein drinks containing either wheat or animal protein, then took blood samples and muscle biopsies afterward. At a matched 35g dose, animal protein stimulated muscle protein synthesis more effectively. However, a larger dose of wheat protein raised synthesis to the same level, debunking the idea that plant proteins are categorically insufficient.
That said, if you’re planning a drastic change, like switching from an omnivore to a vegan diet, get some oversight. Beyond protein, plant-based foods have lower energy density, so fueling for the work required becomes a different calculation.
Practical Takeaway: If you’re an omnivore, don’t worry about the difference between plant and animal protein sources. Standard portions of dairy, eggs, and mixed foods will cover you as long as you’re hitting the targets we covered last week. If you’re vegan, be deliberate, hedge towards the higher end of your protein range, and eat a wide variety of plant sources.
Do the benefits of protein max out after 30 grams per sitting?
Most of you have likely heard that you shouldn’t eat more than 20 to 30g of protein per meal. That came from dose-response studies showing that intakes above that level didn’t further increase muscle protein synthesis. The assumption that followed was that excess was wasted, either burned as fuel or excreted. Recently, that has been challenged.
A 2023 study tested what happens with a mega dose of protein. Most earlier work used doses under 45g and tracked the response for 4-6 hours. This one had 36 healthy men do resistance training, then consume 0, 25, or 100g of milk protein, with blood and muscle biopsies drawn for 12 hours.
After 25g, circulating amino acids peaked and returned to baseline within 5 hours
After 100g of amino acids, they remained elevated for the full 12 hours, and the muscle protein synthesis response was 30% greater.
Most surprisingly, the extra protein wasn’t burned off or wasted. Despite the dose size, amino acid oxidation barely increased.
This substantially weakens the case for meticulously portioning protein into 20-30g servings. Large meals aren’t wasted. They’re digested more slowly and support elevated synthesis for hours.
Practically speaking, though, 100g in one sitting is still a lot of food, and for a runner, a single hyper-dense meal may cause GI distress. Spreading it out remains more comfortable for most.
Practical Takeaway: you don’t need to micromanage 30g doses across the day. A low-protein lunch followed by a high-protein dinner is fine. Your body slows its digestion to match the dose.
Do I need to consume protein within 30 minutes of my workout?
Traditional law says yes. You’re given a strict 30-minute post-workout anabolic window, and if you miss it, the benefit disappears.
This has largely been disproven and replaced with a new hierarchy: Total daily protein intake is the primary priority. Distribution across the day is secondary. Minute-by-minute timing is a distant third.
Some experts have suggested replacing “anabolic window” with “anabolic garage door”. A protein-tracing study found that the muscle protein synthesis response to a meal remains elevated for up to 24 hours after a resistance-training workout performed to failure. Eating within a couple of hours is more than sufficient.
Related to this is a popular question about protein consumption before bedtime. As established last week, protein has no storage depot. When dietary intake runs low, the body starts sacrificing muscle to meet its needs. Sleep is an 8 to 10 hour fast, and without incoming dietary protein, muscle protein breakdown could start outpacing synthesis.
In 2023, researchers found that ingesting 45g of whey or casein protein 30 minutes before sleep significantly increased both mitochondrial and muscle protein synthesis rates overnight compared with placebo.
Practical Takeaway: stop stressing about the clock after a run. You can wait for your next meal, and as long as it has enough protein, your body won’t notice a difference. If you want an extra edge, a 35-45 g high-protein snack about an hour before bed keeps synthesis elevated overnight.
If I get injured, how should my protein intake change?
In last week’s newsletter, we established that “you are what you eat.” Your diet supplies the raw materials your body uses to remodel tissue. When you’re injured, adequate protein is what protects or heals the muscle, tendon, and bone.
The problem is that most athletes’ meal schedules are anchored to their training sessions. If you remove the training, it’s easy to let nutrition goals slip away.
So let’s go back to what happens when you’re injured. In all likelihood, you’re moving less (perhaps due to a joint immobilization), which accelerates atrophy. In healthy muscle, movement-based contractions pull amino acids out of circulation. Immobilized muscle has a much harder time using the protein you eat.
At the extreme, bedridden ICU patients can lose about 20% of their muscle cross-sectional area in a single week. A 2015 study found that even twice-daily electrical stimulation of the muscle for a week was enough to prevent muscle atrophy.
Runners aren’t facing anything that severe, but the principle holds. Protect your hard-earned muscle by doing whatever contractions you’re cleared for and “feeding the injury” with a little extra protein.
Practical Takeaway: if your activity levels have dropped dramatically, you can probably scale back fat and carbohydrate intake to match your lower energy output, but I would raise protein intake to around 2.0 g/kg/day.
Hi Alex—this is a thoughtful and well-researched article. I especially appreciate that you challenge the persistent myth that plant proteins are “incomplete.” Plant foods contain all nine essential amino acids—and all 20 amino acids used by the human body—although the relative amounts vary among foods. (Along those lines, you may be interested in this review by Gardner et al. https://academic.oup.com/nutritionreviews/article/77/4/197/5307079)
I would, however, question the assertion that plant proteins are inherently less digestible. The DIAAS system, which attempts to account for digestibility and amino acid availability, has significant limitations. Much of the underlying research uses animal models and uncooked, isolated foods—conditions that do not reflect how humans typically eat. The methodology also applies assumptions derived largely from animal proteins that may underestimate the value of plant proteins. Additional limitations are discussed in this review (https://link.springer.com/article/10.1007/s13668-020-00348-8). When people consume a varied diet containing complementary plant foods, overall protein quality can achieve a DIAAS above 90.
Muscle protein synthesis studies also have important limitations when used to determine long-term protein needs or outcomes. Most measure the acute response to a single meal, which may not reflect what happens after the body adapts to a dietary pattern. For example, this study found that although acute MPS was initially higher with an omnivorous diet, the difference disappeared after 10 days. (https://www.sciencedirect.com/science/article/pii/S002231662401246X?via%3Dihub) The authors concluded that plant-based protein sources did not compromise daily MPS rates compared with an isocaloric, isonitrogenous omnivorous diet in older adults.
I wholeheartedly agree with your “food first” approach. The food matrix and the broader dietary context matter—particularly for long-term health. Whole foods provide far more than protein. That said, of the protein sources you highlighted, only legumes and tofu provide meaningful fiber and many of the health-promoting compounds, including polyphenols, that are largely absent from animal-derived protein sources.
Fiber, polyphenols, and the gut microbiome may be an overlooked part of the muscle-health equation. Research in this area is emerging and worth considering, especially in the broader context of skeletal health and function. In animal models, postbiotics—compounds produced when beneficial gut microbes ferment fiber—have been shown to stimulate MPS, reduce inflammation, improve insulin sensitivity, and enhance endurance. Each of these effects could potentially support muscle preservation, although evidence in athletes remains limited. I discuss this developing research in more detail here: Is Fiber the New Protein? https://sharonmcdowelllarsen.substack.com/p/is-fiber-the-new-protein?r=3mc502
Protein adequacy is an important but complex subject. We need more studies examining whole-food protein sources, particularly in highly active individuals. We also need to move beyond short-term MPS measurements and study the outcome that ultimately matters most to athletes: performance. Unfortunately, those data remain sparse. So far, the evidence consistently suggests that when athletes already consume adequate or even minimal protein, increasing carbohydrate availability is generally more effective for improving endurance performance.
Thank you for your thoughtful work—and for considering another perspective.